i know it's beautiful this is
spectacular we even thought we'd be
alive at this point well i mean
the fact that these go right up like
that
and then down you know this is
astonishing
look at how steep that is
i love checking not your two thousand
nothing
i know it's beautiful it's spectacular
it's a fairly long slew
good afternoon welcome to nasa
headquarters and today space science
update we're very pleased
today to have a panel of astronomers
here to make a significant announcement
on research funded by nasa and the
national science foundation and uh here
to tell us about that
and to introduce our panel to tell us
about that it's dr ann kenney who's the
director of nasa's origin programs here
at nasa headquarters and
uh we have some very exciting science to
talk about today
which has to do with uh planet searches
when you look up in the night sky
now you know with a certainty that there
are planets around some of the stars in
that sky but this has only been the case
since 1994 before then
it was simply not known people thought
that there were probably planets out
there but it wasn't known since 1994
we've discovered about 30 planets i use
a wee very loosely here
since this was not my personal research
but we've discovered about 30 planets of
those 20 of those planets were
discovered by the team that is here to
talk with us today
i would just like to say something about
those planets to put this in perspective
those 30 planets have all been
jupiter mass or larger that means 300
earth mass sized planets
and
the the planets we're going to talk
about today have more to do with
saturn-sized planets which is
100 earth mass so very different order
of magnitude
so as i said
of the of the approximately 30 planets
that we know of 20 of them were
discovered by this team and
this is this is a group that has been
working on this field for approximately
15 years this is very hard work it's
very exacting work
and uh you know i'm really i'm really
pleased to have this group to talk to us
today the the scientists as well as our
uh science experts who will comment on
it so let me let me introduce today's
panel um the
jeff marcy and paul butler are people
that i've known for 15 years myself and
that that makes it a double pleasure
jeff marcy is from university of
california in berkeley
paul butler is from carnegie institution
at washington dc here in town
alan boss
is also from the carnegie institution of
d.c
and heidi hamill from the space science
institute in boulder colorado so jeff
would you like to start out and tell us
what you've found
using the world's largest telescope the
keck in hawaii
and using some new improvements to our
search technique
we have discovered the first
saturn-sized planets ever found outside
our solar system
in fact we found two saturn's and i'll
be showing you the data for these in
just a moment
one of the saturn's orbits the star
called 79 seti
in the southern hemisphere
and
one orbits the star called hd-46375
both of these stars being old sun-like
stars
an artist's rendering is shown in the
animation if i could have it please
this shows a star field and then the
star itself 79 centi and what the
saturn-sized planet may well look like
the artist's rendering shows the size
and orbit of the planet that we actually
measure
and it also shows rings and moons drawn
speculatively to mimic
our own saturn in our solar system
our search technique is is well known to
many people now it involves monitoring
the wobble of these host stars
shown in the next animation
what we detect of course is the wobble
of the star the motion of the star as it
responds to the gravitational pull on
the star exerted by the planet
this wobbling motion of the star tells
us a number of
facts about the planet it tells us the
minimum mass of the planet and it tells
us the orbital size and the orbital
shape within which the planet resides
let me
turn now to the data itself what's uh
really precious to us
the data are shown in the next graphic
the data reveal these saturns and these
that you see here on this graphic are
the data
for the star 79 seti
what you see are the
velocity measurements the dots
versus time on the horizontal axis
taken during the last two years at the
keck telescope you can see that the
velocity of the star
varies back and forth like a buoy
on water waves indicating that 79 seti
indeed wobbles back and forth it has a
saturn mass planet one can use newton's
laws of physics to deduce the mass and
orbit of the planet and that the planet
goes around the star 79 centi uh in
about 75 days
the planet's orbit
around 79 seti is similar in shape and
size to
mercury's orbit around the sun
same distance and even more eccentric
for this this planet a more elongated
orbit
and then finally the last graphic i'd
like to show uh indicates the data we've
acquired for the other star hd
46375
here you're only seeing three days of
data compressed down to three days and
you can see that the planet orbits the
star in only three days one full wobble
in three days and so this planet is very
close to its host star the planet indeed
is about 25 times
closer to its host star than our earth
is to the sun
so it's scorchingly hot on this planet
we estimate the temperature on the
planet to be something like 2000 degrees
fahrenheit due to the proximity of the
planet to the star
and i think now i'd like to turn to paul
butler who can tell us a little more
about the interpretations of these data
thanks jeff
i'm really excited about these
discoveries because they mark two
important mileposts uh in our
exploration of planetary systems uh
because of the way that these planets
are different from the ones that have
been found up until now
but first i'll talk about how these
planets are similar to what have been
found up until now and how they relate
to the planets that have been found
so far all of the planets that have been
found fall in one of two classes they're
either these 51 peg-like orbits four-day
orbits where the planet is roasting hot
or they're more distant orbits but
eccentric not circular orbits like we
find in our own solar system
and these two planets actually fall one
in each class hd 46375 is one of these
51 peg roasting planets
and 79 ceti is eccentric so they've
fallen in the two classes that have been
found up until now
these classes are very different from
solar system planets solar system
planets uh are in beautifully nested
concentric circular orbits and so this
has caused speculation that the planets
that have been found to date are somehow
different than solar system planets
the way we can address this issue is to
look at the mass distribution so if i
can have the mass distribution graphic
what this shows is the number of planets
that have been detected
versus how much mass each planet has so
you see the the scale goes from about 0
to about 15 jupiter mouses
and the thing that initially was quite
startling to us is that we're finding
almost nothing that's this bigger than
about 10 jupiter masses or so such
planets are or such objects would be
very easy to find by virtue of their
huge gravitational field you get
enormous wobbles and yet we're finding
none uh instead what we're finding is
just a trickle of planets uh sort of
between five and ten jupiter masses and
then as we move to smaller mass regimes
one and two jupiter mouses we're finding
just a torrent of discoveries that are
coming through
now the critical thing here is that
these planets that the smallest end the
one and two jupiter mass planets are the
hardest to detect and the ones that we
are most likely to miss in our surveys
so this suggests that there's going to
be many many many more small planets
than there are large planets and of
course the discoveries that we have
today pushed us to even lower masses for
the first time going under 100 earth
masses
now i'd like to talk about uh
why these two discoveries are so special
why they mark two important mild posts
um
first is simply that up until now the
planets as has been stated the planets
have been found are more like jupiter
mass sort of 200 or more earth masses
and uh the one enormous milestone now is
that these things are about 70 to 80
earth masses we've passed 100 earth mass
limit and pushing down even further
um and the second thing is uh this
points out sort of the future so if i
can have the 79 steady graphic again
up until now we've only been able to
find planets that induce really huge
wobbles in their star wobbles that are
about four times bigger than jupiter
induces in the sun and with 79 seti for
the first time we have a wobble here
which is plus or minus about 11 meters a
second which is actually smaller than
the wobble induced on the sun by jupiter
so for the first time we are now
demonstrating that we can detect solar
system like planets uh a real-live
jupiter-like object and a real-life
jupiter-like orbital distance things
that would remind us of ourselves
this is in fact now the biggest
remaining long-term goal of this program
to maintain this kind of precision for
another decade so that we can answer the
the huge looming question what fraction
of these planetary systems are going to
be like our own uh is our own system
rare or is it common completely open
question that we hope to be able to
provide preliminary answers for within
10 years
that's basically my set of comments i'll
turn it over to ann now
thanks paul and jeff i think this
represents an incredible achievement and
very impressive science
so i'd like to turn it now to uh alan
and heidi and ask for uh comments and
context on these results alan okay
i'd like to comment on the
importance of these discoveries within
the context of what's been discovered so
far as well as what will be discovered
in the next few years so if i could have
the discovery space image please
this uh this plot shows you not only the
masses of the objects which have been
discovered so far but also their
separations from their stars
and you can see that there is at the top
of the of the field there are a few
possible brown dwarf companions to some
of these nearby solar type stars but
they're quite rare and surprisingly rare
and there's a rather large gap between
the least massive brown dwarf star and
what we think is the most massive planet
around at around 10 jupiter masses
then below 10 jupiter masses there's
this
grouping of objects that we believe are
gas giant planets very similar to our
own jupiter and there are roughly 30 or
so those objects now
now what you see is first of all at the
very bottom are the two new discoveries
uh highly in in pink hd 46375 and 79
seti those are the two newly discovered
planets and as paul pointed out they map
out a new area of discovery space
they're pushing down the region where we
can find extrasolar planets to
considerably lower masses than what
we've seen before
the first point i want to make about
this though is what you don't see on
this plot which is that you do not see
another gap
you see there's a gap up at the top of
the plot that helps us separate out
brown dwarf stars from gas giant planets
but there's no such gap evidence in the
distribution of what we believe are
planets implying we really are seeing a
continuous distribution in masses of
objects that are gas giant planets and
going into the range perhaps of ice
giant planets eventually and so what
we're seeing is really just the tip of
an iceberg that there is an
incredible number of other plants we'll
be finding as our search techniques
improve if i could have the graphic
backing i want to make the second point
which is actually mentioned by by paul
again
name you'll notice that 79 seti is
sitting out in a region of parameter
space that is
untouched by previous observations all
the previous observations lie above that
top dashed line called old detection
limit which tells you basically that
with a certain amount of precision of
your radial velocity search you can find
everything above that line
79 city for the first time defines a new
line the line says which says new
detection limit pushes it down into a
regime where we can expect to find
around other stars jupiter
analogs that is truly jupiter mass
objects with 12-year period orbits like
jupiter in our solar system and that
sort of
object is really in many ways the holy
grail of what we're after now because
such an object could actually uh
also
be a signpost for finding an earth-like
planet which is which is really what
we're trying to find and holy grail is
sort of a term that gets used and
overused too much i've tried to think of
another analogy i thought perhaps the
golden fleece but of course that has
some rather unfortunate uh connotations
because of senator william proxmeier but
you get the idea we're looking for
something which is very valuable and
very hard to find and the real goal of
much of this long-term program is to try
to find a habitable earth if we can find
a long period jupiter around a nearby
star then that will tell us that might
be a very good candidate for looking for
another earth and my colleague heidi
will be telling us a bit more about what
we can expect to find in the next few
years
that's right i'd like to actually go
back to that graphic again it's a very
complicated graphic but it has so much
information
it really tells us a very a great deal
about what we're talking about today i
also want to highlight something that's
not on this graphic and that is
other planets in our solar system
to really put this in context for you
you see the two uh points there of the
new star the new planets that have been
found and you see jupiter which lies
within the space that we can detect but
saturn is also not in the realm of
detectability by this technique um with
the kinds of work that this team is
doing they're pushing and pushing and
pushing and they probably will be able
to get to well they have gotten to
saturn masses but they haven't gotten
yet to
saturn
orbits and they'll probably be able to
push down the uranus masses too and i
expected a year or maybe even less than
that we'll be hearing from them again
about uranus-sized planets but what
about earth-type planets where would
they fall on that graph that we're
talking about the answer is earth
doesn't fall on that graph it's so far
below it's so small that you wouldn't
even see it on that figure and so we're
really
when we're looking to the future
we're really looking at even
different techniques we're looking at
space-based missions to find terrestrial
planets and that's of course another
holy grail if you will or golden fleece
we're really looking hard to find
terrestrial-type planets it's a key goal
of what nasa is trying to do
and for that we're going to need to go
into outer space and we're going to be
needing slightly newer techniques we're
going to be needing to use techniques
called interferometry for example the
space interferometer mission we'll also
be looking at
the terrestrial planet finder mission
these are going to be
very
important things that we're going to do
in the future the important news today
the reason we're here talking to you
is that the discovery of
saturn-sized objects is an extremely
critical step
towards finding terrestrial type planets
we are now as we've said pushing
boundaries that we have not pushed
before and so that is why we are all
very excited about today's results
thanks heidi
and before we go back to don i'd just
like to ask jeff and paul
what these discoveries tell us about our
own solar system
i think one of the remarkable
aspects of these discoveries and our
previous ones is that for the first time
in human history we can compare
the characteristics of our own solar
system with the exquisite nine planets
one of which we cherish the earth
all of which reside in circular orbits
some of them are massive like jupiter
and saturn some of them are rocky like
the earth mars venus
and we have the opportunity now finally
to compare our solar system
to planetary systems as a generic class
in our milky way galaxy
and the early signs are a little bit
frightening actually and it is in brief
that
the planets we are finding as paul
alluded
typically are in elongated eccentric
orbits rather than circular orbits that
characterize the nine planets in our own
solar system and so the early returns in
this poll of planets suggests that our
solar system is somewhat unusual this is
an entirely preliminary thought because
we have not yet discovered true jupiter
analogs
that alan and heidi were referring to
and when we can find jupiter analogs
that orbit as far from their star as our
jupiter orbits the sun then we'll be
able to do a direct comparison but the
early suggestion is that the orbits of
planets around other stars are more
eccentric than those in our own solar
system and this may have something to do
with the fact that biology and life has
flourished here on the earth in our
solar system
i'd like to um go back to the mass
distribution diagram for just a moment
uh
one of the extraordinary things about
the distribution of course is that as
you go to lower masses you're seeing
more and more objects although they're
harder to detect
and if we are to maybe somewhat wildly
uh extrapolate that diagram down to
earth masses the early suggestion is
that earth mass planets are probably
extremely common in the galaxy the
galaxy might just be littered with earth
mass planets
um the second point is jeff was
referring to was of course the
habitability of these potential earths
and um
the eccentricity of the orbits of course
of the planets we're finding right now
probably rule out nice stable uh
earth-like orbital positions where you
get liquid water
um we can have the uh the graphic of the
orbital distribution or the uh the
orbits
in this diagram here you see where the
sub-saturn that was that we're
announcing today 79 seti how it fits in
relative to the solar system a planet
like this
eve it's about a border hundreds uh
earth masses would make stable orbits in
the inner solar system impossible so if
such a planet were in our own solar
system we wouldn't be here um it
turns out that uh in addition to the
fact that our orbit is circular which
makes for a nice stable uh climate and
allows liquid water to exist year round
and life to flourish
the other planet that's critical to our
life uh is jupiter and the circularity
of jupiter's orbit because jupiter is
the big boy on the block uh more massive
than all the other planets combined
whatever it does it enforces on
everybody else and by virtue of the fact
that jupiter is in a circular orbit it
enforces circularity on the rest of us
jupiter does a second extremely critical
thing which george weather pointed out
it acts as an enormous gravitational
vacuum cleaner sweeping up all of the
comets and asteroids which might
otherwise smash into us and so instead
of having uh one of these huge dinosaur
killing impacts every few weeks we only
have them every uh 10 or 30 million
years so jupiter has these two critical
things to make our existence possible
and that's why it's so important for us
to find solar system analogs
jupiter-like planets orbiting out of the
stars
jeff just mentioned that the early
returns don't look good that most these
things are eccentric it should also be
said that we're finding planets around
about five to ten percent of the stars
right now and what's going on with the
other 90 to 95 percent of the stars
simply isn't known at this point we need
another 10 years of data to make any
speculation whatsoever so the field is
completely open at this point whether
it's every other star that has solar
system like uh objects or every 10th
star or every 100th or every thousand
star completely unknown at this point
and we hope to be able to provide some
empirical limits within the next 10
years
and thanks paul and jeff that's a
beautiful description of our solar
system as a sort of uh family that
protects
where the different members protect each
other for uh developing uh don
all right well thank you very much uh
we'll uh start with questions here at
nasa headquarters and then check our
centers for
go and give your name and affiliate jeff
borenstein night reader newspapers for
dr marcy uh can you tell us exactly what
you did to refine your technique to find
it this way and is there what
on this graphic it talks about new
detection limits is there a discernible
detection limit that you see given the
existing technology is this it or how
far much further can you will you be
back here a year or two years from now
what has made these
saturn discoveries possible is indeed
some new breakthroughs technically
in our work at the keck telescope and i
should say that our other collaborator
steve vogt has led the way in this
uh he built a spectrometer which is at
the back end if you will of the keck
telescope five million dollar
spectrometer without which we wouldn't
detect any of these planets
and what we've done in the last two
years paul and i and steve is to learn
some of the nuances the idiosyncrasies
if you will of the behavior of this
spectrometer it's a complicated optical
device nobody could have predicted its
actual performance ahead of time and
we've done a large number of tests
indeed paul and i have spent the
majority of our time carrying out tests
of the performance of the spectrometer
and developing software indeed paul has
led the way in this writing software
that accommodates the idiosyncrasies of
the spectrometer we account for all this
odd behavior
subtracted away from our measurements
leaving us with just the clean data the
clean wobble of the star so that's an
enormous uh boost forward making these
ever smaller planet detections possible
the ultimate limit
is indeed ahead of us
we are measuring the velocities of stars
to plus or minus three meters per second
which is sort of bicycle speed uh it is
remarkable if i may reflect on that for
a moment these stars are enormous
spheres uh a million times bigger than
the earth they are two or three hundred
light years away and these globes of gas
can be measured to plus or minus
bicycling speed
but we are at that point and what we'd
like to do is to measure the speeds of
stars even more accurately to human
walking speed about one meter per second
and i think paul and i feel that that's
a realistic goal given the
the known vagaries of the equipment the
light gathering power of the keck
telescope and we think
with the new improvements that we have
coming down the line we will be able to
detect not just saturn's but neptunes
which are about third the mass of
saturn's
we probably will not be able to go
further uh frankly we'll be out of
business we think in ten years when we
found the saturns as well as
the neptunes and then the jupiters being
cleaned up
we will need indeed to turn to the new
technology that nasa is developing
space-borne telescopes without which we
will never detect earth-like planets
so you might say this is somewhat
unusual and nasa is uh supporting you
know ground-based astronomy but for us
this is a very long-term commitment we
we need the planets
that these guys are finding and i really
would like to emphasize that this is not
uh this is not something they developed
the last 15 minutes these guys have been
at work on this for 15 years when i
first knew jeff 15 years ago i went to
visit uh their setup at lick observatory
and uh you know they were hard on work
on the zeroth generation of of this
technology it's extraordinarily
difficult work that is very precise and
you have to
really be intrepid to succeed at it
leonard
yeah leonardo david with space.com sort
of a little bit on the same wavelength
what about the complementary nature of
the techniques you're using for space
based are you coming up with techniques
that could be applied to space
based instrumentation
i get some sense here there could be a
race between
breakthroughs on the ground with
technology and what nasa is going to be
funding to spend big dollars to put in
space
shall i try it go ahead um
actually i see it a little differently i
see the
ground-based efforts with keck and other
large telescopes as as complementary and
early reconnaissance
for the space-born work that nasa will
be doing and which will you know blow
our minds away i think when it happens
and the reason i say this is that our
technique is just limited we really will
not be able to detect the rocky earth
mass planets the spaceborne techniques
both the space interferometry mission
called sim
being developed here at nasa and also
the terrestrial planet finder mission
also developed here at nasa those two
are targeted specifically to find earth
type planets we can't touch that so in a
way we're operating in parallel the
reconnaissance we do now uh will tell us
which stars have the big bullies the
giant planets they may be signposts for
the earth-like planets that nasa will
come through and detect uh in the coming
decade or two
come on
there's also another element of
competition uh in that nasa has recently
approved another space mission called
fame for the full sky astrometric
mapping explorer which finds planets not
by looking for the doppler shift of the
star but looking for the positional
wobble of the star on the sky
and fame will actually have the ability
to find these long period jupiter-like
planets that that jeff and paul can find
from the ground so unfortunately jeff
and paul have a several year ahead start
fame won't be launched for a few more
years but once it gets up in orbit it
will also be looking for planets in that
same area of parameter space where
jupiter-like objects exist so in this
sense
it's really very good because
competition we all know leads to people
to make sure they're doing the best
possible job but it's also very
important because it will mean that
there will be at least one other
technique to confirm
each other the radial velocity confirms
can confirm instrumentary and vice versa
which is of course
something we really have to
not
forget about in any very difficult
astronomy you really want to make sure
that any dubious measurement can be
confirmed by another measurement and so
you really are finding something which
is reproducible but this is a very
exciting time in a field i mean to only
know 34. with today's announcement i
believe the number is 34. i mean we only
know of 34 planets outside of our solar
system and this is brand new we're going
to learn what animals are in that zoo
and we have no idea today it's going to
be very exciting
bob
sorry i'm sorry one of you mentioned
that neptune when do you mention uranus
which is the
outer limit of what you might do from
groundbreaking i think we've got the
expert
well actually he said they're going to
be looking at at neptune but i think
that uranus is probably going to be
easier for them to find because they're
comparable masses but uranus is closer
in so it has a shorter period and so it
just the closer it is to the star the
easier it is for them to find
also
does your 34 population include those
so-called free-floating planets that the
royal academy society talked about last
week
i don't think so uh those are brown
dwarfs i believe i believe they aren't
what we would call planets they're we
call them and this isn't meant to be
derogatory they're called failed stars
down front and then
randy shostak reporter with eos news
at what point in your research of these
planets did you
did you say okay we've got uh some other
planets and these are different and what
were your initial reactions
well um
these discoveries both sort of came on
slowly these were not the sort of eureka
moment discoveries we've had those also
uh in the case of 79 seti we actually
had a 75 day orbit for that a year ago
and we sat on it for an additional year
to make sure that all the data
absolutely fit it exquisitely otherwise
we would never have announced uh in the
other case 46 375 that's got a slightly
larger amplitude the amplitude for that
is about 35 meters a second that's about
three times larger amplitude which means
it's three times easier to detect so
again that that one didn't really push
the system as much it was 79 seti that
we really had to sit on for a long long
time to make sure it was absolutely
right
yeah i'll just follow up to say that uh
to confirm what paul said i was going
back to my emails to remind myself of
the history of the discovery of the
planet around 79 centi and i have an
email from paul that's dated august
of 1999
so i guess that's eight eight or nine
months ago and in the email paul lists
four or five hot candidates that he had
sifted through and discovered in our
existing database
and 79 said he is in there so back in
august
the email from paul said it looks like
it's a 75 day period and the orbital
radius is blah and the mass is blocked
and what we normally do at this stage is
to wait a year typically gather more
data and indeed the data for the past
year has simply confirmed what we had
known back in august of 99
but let me repeat the question he asked
how did you feel when you found these
sub saturns
um i would have been more shocked if
we'd not found them
we built a technique which can find
saturn mass objects within one earth
orbital distance and if we hadn't found
them that would have been infinitely
more shocking because that would have
been there was a gap in the mass and
maybe the objects we had found today
weren't related to solar system planets
but in fact we're seeing no gap as the
technique gets better as our precision
gets better we're finding smaller and
smaller planets and that's exactly what
we expect if these things are in fact
planets as our own planets are
so would have been shocking not to find
them
and i'll add another comment to that
with regard to our emotional reactions
it's very interesting
when paul and i and i i can speak i
think for both of us here when we see a
potential planet coming down our
conveyor belt of data
we are indeed
excited we're happy we're you know we
work very hard for those moments but
frankly the
elation is usually tempered by the
fright that we've made some mistakes
somewhere and indeed that's why we spend
an extra year following up
doing some calculations some theoretical
work we talk with our colleagues
and we try to ascertain whether there's
some way that we could have gone wrong
and paul and i i think it's fair to say
are proudest of the fact that of the 24
planets we've discovered we've never
made a false claim in the past four and
a half years or so and it's a it's a
track record that comes from fear and
concern about making mistakes and
so um you know our excitement always is
tempered by sort of the objectivity of
going back to the blackboard and trying
to figure out what we can do even better
to confirm what we suspect
we'll take out two more questions here
first then go to ames and then come back
to headquarters so kurt go ahead
curtis who played with the washington
post can you explain to us just a little
bit more that uh what precisely
breakthrough it is that you're talking
about in the detection there's no new
detector the resolution is the same the
instrument is the same
so what is the technological
breakthrough specifically that you're
describing we model the spectrometer
better now as the bottom line
these detections are really incredibly
minute uh
literally at the point of olympic
sprinting speed you know uh
and uh it turns out very very teeny
changes in the spectrometer very very
teeny changes in how the light is
focused by the spectrometer can dwarf
our signal and we need to actually build
a physical model of our spectrometer in
the computer and we've made significant
improvements in our modeling within the
last year
okay we'll take one more question here
all right mary oh sorry sorry i just i
you know for us that's the key question
actually that you've asked and i'll just
say somewhat more quantitatively
up till a year ago
the precision with which we could
measure the speeds of stars was plus or
minus eight meters per second
and only in the last 6 to 12 months have
these improvements that paul mentioned
building a computer model of our
spectrometer allowed us to achieve a
precision of plus or minus 3 meters per
second in fact paul and i think that our
precision is even a little better than
three meters a second so we have
demonstrable improvements both in our
results and in the approach that we took
to get to these results
okay
how many other objects do you have on
that hot list of candidates that you
discussed from august of 99 and when
might we learn of those
uh
it's uh reminds me a little bit of the
uh you know when you ask how many
potential jupiters are are stored on our
hard disk that we haven't yet revealed
it reminds me a little bit of the i love
lucy episode where lucy says to herself
i can have a job and make money and she
goes to be a
quality checker at a candy factory
and the candies come down the conveyor
belt and she sees them coming down and
there's more and more candies and she
can't check their quality and she starts
eating them
to just handle the flow paul and i are
in a very lucky era which i think we're
both
just ecstatic about actually and that is
we can indeed see down the line there
are something like six to ten
planets that we know of that we've
emailed each other about that we talk
about when we're at the telescope that
look promising we are waiting for
another half a year or year or maybe a
year and a half of data to confirm these
planets
some of them are jupiter-sized we have
one i think it's fair to say that's
about a third of a jupiter size very
close to a saturn we decided not to
announce it today but it's a dead ringer
for something about very close to a
saturn size just a little above
so we have a lot of them were the keck
telescope is just this marvelous machine
for finding planets with the
spectrometer and we feel very lucky to
have been in the right place with the
right telescope to to have this conveyor
belt of planets occur
okay we'll take questions from the aims
research center in california and please
give us your name and affiliation
hi this is glenda chu from san jose
mercury news i have two questions the
first is is there any indication that
either of these planets could harbor
liquid water
um
it's very unlikely that these planets
would have liquid water uh
hd46375 is in one of these three-day
orbits and so it's going to be heated to
like about 2000 degrees fahrenheit
uh the other planet 79 seti is in a
75-day orbital period the orbital
distance is in fact very similar to
mercury in our own system so it's also
going to be far far too hot
so sadly no liquid water on these
systems
question is can you say something about
the status of these space-based missions
that would look for earth-sized planets
how far along are they in the conveyor
belt of nasa uh well let me address that
there's uh
there's really a uh
a sort of line of these projects that
are very interwoven
um and we we start on the ground
actually with the keck interferometer to
try to to really get a grasp on optical
interferometry from the ground and then
we do a technology test in space it's
called space technology three
and and that is to get a grasp on
formation flying from space because
that's what we eventually have to be
able to do to find the earth-sized
planets we have to do formation flying
and then we get a grasp on doing
informatory in space so that's the space
interferometry mission and then after
that and only after that after we have
proven each
brick of technology in the wall only
then do we go on to the terrestrial
planet finder where these different
technologies are all utilized so so this
is a this is a challenge nobody says
this is easy and i think if it were easy
and trivial we probably wouldn't be all
that interested in doing it uh it it's a
challenge and there is a uh a very
concrete plan in how to proceed
more questions from ames
yeah i'm later back from a brazilian
daily newspaper we started sao paulo and
my question relates to the orbits of
these new systems uh you said they are
most of them are eccentric
and our own solar system has concentric
orbits i wonder
if you have a good explanation for that
and if it's related to the age of each
system
um
the
stars
which we have discovered having these
planets in eccentric elongated orbits
have all types of ages some of the stars
are very young
in astronomy
terms that means the stars are only a
billion years old
and some of the stars are quite old 10
billion years old and stars of
either great youth or great age both
seem to have these eccentric oval orbits
we think but it's in the theoretical
realm that the oval orbits of the
planets stem from gravitational
slingshotting of one planet off of
another uh but we're not really sure
this is in a realm where we need to
gather more data and turn to the
theorists who are generating we could
try turning to our yeah and i was going
to say alan boss may have some ideas
about where the eccentric orbits come
from yeah that's actually an excellent
question in fact i think trying to
understand the eccentric orbits of these
new extrasolar planets is one of the
major theoretical problems it's
outstanding at this point it's really
very much a surprise because all we of
course had known before this was our own
solar system and so theorists had spent
several decades trying to explain
circular orbits now suddenly they
realize they've got to explain eccentric
orbits as well and one possible
explanation is what jeff just pointed
out that perhaps when you make several
planets they end up so close together
that they gravitationally perturb each
other
even if they start out on circular
orbits they kick each other into
eccentric orbits that's one possible way
of doing it although you have to worry
about making them so close together in
the first place which is probably the
biggest drawback to that particular
mechanism
there is another possibility though
which is that if you make gas giant
planets through a disk and stability
which is not the preferred way of making
it if you make it through a disk which
is cold enough and massive enough to
clump together into large balls of gas
through its own self-gravity
some recent simulations that i've been
working on at least imply that when
those clumps first form they start out
on
eccentric orbits so it could be that
that particular mechanism actually
produces clumps with eccentric orbits
but that's really
pretty much premature to make that claim
at this point because these are
calculations that need to be reproduced
by other workers
in terms of the conventional making
jupiter where you build up a solid clump
and then pull gas onto it those models
pretty much imply that you start off on
a circular orbit so we've got a real
puzzle here well let me address this
also
one thing we need to stress is that we
actually have been finding jupiter-sized
planets but we haven't yet seen
a jupiter a true jupiter analog in other
words one that is at jupiter's distance
from our sun we have not yet found a
solar system like our solar system and
that's because we you guys haven't been
observing long enough you should be back
at the telescope for another ten years
and and then after that then we might be
able to find solar systems that are like
our solar system at this point we just
don't have enough data yet
okay we'll come back here to nasa
headquarters and take more questions go
ahead seth
for dr marcy just to continue on that
line you mentioned that perhaps our the
more
normalized circular concentric orbits of
our solar system are rare
is um how i guess i know that's more
theory how confident are you that you
that uh you they just aren't that a lot
of those out there that you're not
seeing
versus that they are rare i'm trying to
understand why you're leaning toward
that way yeah it's a good question um
here's the situation paul and i have
been using the keck telescope uh for the
past four years
and i should say by the way that we're
greatly indebted uh both to nasa and the
national science foundation for the
funding to let us do this and also to
the university of california that also
operates the keck telescope and i bring
this up because during the past four
years we've been gathering data
which allows us to detect planets in
orbits that take about four years for
the planet to go around if a planet took
more than four years to go around its
star we haven't been watching long
enough
and so with
nasa and the university of california's
help as well as nsf we hope to continue
this project for another five or ten
years and only then will we be sensitive
to planets that orbit farther away
namely the orbits that take longer to go
around their host star so the bottom
line is absolutely right as all i think
all of us now have touched on
we are very excited about the prospect
for the future which is to detect
planets that take as long to go around
their star a decade or two decades as
the giant planets in our solar system
take to go around our sun
but if scientists have 30 objects
they're going to start making
conclusions about 30 objects
who can resist that temptation
back over there i'm dan vergano with usa
today
i had
two questions really
on the wobble charts you showed the data
points i'm curious about how many data
points does it take
to
for you to say looks like one
um we get early hints literally by the
fourth or fifth observation
but we can't really get a good orbit
until we've got about 15 or 20
observations
and the observations have to be over a
time baseline that's longer than the
orbital period
and the other question is uh can you
tell me have you ruled out any stars or
about how many have you rolled out as
hosts for these hot roasters or et
cetera yeah the the hot roasters you
know if you pick a mass limit like a
saturn mass limit it's easy to rule out
you know
my guess is right now probably only
about one star out of every 200 has got
one of these hot roaster planets in sort
of the three to five day orbits
the uh
maybe the more exciting thing to rule
out is the presence of solar system
analogs
and while i wouldn't i wouldn't go so
far to say we can rule any out we do see
a lot of stars that are just flat line
dead stable that show no velocity
variations above our measurement error
of three meters a second and we're
seeing this now over four years five
years or so so those don't look real
promising um but let me just ask what
how many meters a second does the earth
tug the sun okay earth tugs the sun by
an imperceptible amount it's about one
tenth of a meter per second and
no technology in the world can come
close to that right now but jupiter
jupiter tugs the sun by 12 and a half
meters a second um so with 79 seti for
the first time we're measuring things
that have a smaller tug than that so
jupiter's are now detectable after half
a jupiter orbital period you expect to
see the star wobble by border 12 meters
a second and we have a number of stars
that after four or five years are just
dead at the three meter per second level
and so
i would say of order a quarter of our
stars don't look real promising for
having anything that we can detect uh
but it'll be fun to do this for another
10 years and more properly answer your
question
okay we have several more questions to
go and
stu magnuson with uh space news
uh i just want to clarify some of you
kind of answered two questions ago but
are the wobbles uh for our eccentric
orbits easier to spot than the circular
orbits and how many have how many
circular orbits have you found so far if
any
the
um
the best way for me to answer the
question is this it's it's a little bit
of a complicated question
i would say the following
almost all of the planets
that have these elongated eccentric
orbits we would have detected them just
as easily if they had been in circular
orbits and and the way i'm answering it
is i think the important way because
your question is a good one we are we
one might well worry
that we have some
bias toward detecting the elongated
eccentric orbits over our ability to
detect circular ones and that's not the
case the the orbits that we've detected
that are elongated eccentric these wacky
orbits
if the planet had been
in a circular orbit we would have found
it just as well
okay
so um
here's the statistic
for what it's worth
we
there are 24 planets known around other
stars that orbit farther than a tenth of
an earth-sun distance and every single
one of them 24 out of 24
orbits in an elongated eccentric orbit
the planets that we've found and other
teams the swiss team has contributed
several those planets that orbit closer
than one-tenth of an earth-sun distance
all of them are in circular orbits
and some people speculate that that may
be these circular orbits may have
resulted from
tides raised on the star and indeed
tides raised on the planet due to the
star which tend to circularize the orbit
even if it were not circular to begin
with
so the interesting statistic is the uh
24 out of 24 planets beyond a tenth of
an earth sun distance
that are in these elongated orbits
there are several of those though that i
think are
are
the planet orbits far enough away from
its star that the star probably hasn't
had enough time to circularize its orbit
so even though they're on circular
orbits those circular orbits are
probably primordial but as you go
farther away as jeff pointed out they're
essentially all eccentric so there's
some real puzzles there theoretically to
explain
okay we'll try to take them in order
randy and then paul
how do you explain the detection gap
between the brown dwarfs and the planets
that have been found and why hasn't
anything been found in the gap
brown dwarf companions the stars are
rare um at least within the inner three
times the earth sun distance which is
what we're probing now three times
anything within about three earth sun
distances of its star
we don't find any brown dwarfs we have
one thousand stars under survey we had
three telescopes we're doing a full sky
survey we're going to extend that to
2000 stars out out of 500 stars that
we've carefully examined now over three
or four years there aren't any we don't
see a single object so they're rare
brown dwarfs wild brown dwarfs are very
common there's probably two brown dwarfs
in our galaxy for every star uh for
whatever reason the brown dwarfs do not
form around stars at least within the
inner part of the solar system and
that's up to somebody like alan to
explain that
it's just empirical i can comment on
that also uh we have to remember that
discovery space diagram we showed is
actually for companions to solar type
stars stars like our sun if you did a
similar plot for companions to brown
dwarf stars you would find they all have
a brown dwarf companion at least half of
them do the point is that if you look at
binary stars binary stars tend to have
roughly equal mass companions or at
least a companion that's perhaps no more
than a third or a fifth of its mass you
start getting down to 101 mass ratio
which is where you would be for a brown
dwarf companion to a
sun-like star those things just are very
rare we know from looking at other
binary stars so when you form two stars
they tend to be roughly equal mass
and so that's why the solar type stars
essentially have zero brown dwarf
companions and that but that gives us a
great handle for making the argument
that we've really found something
completely different here that we're
finding planets not brown dwarf stars if
it turned out that brown dwarfs could
co-exist with planets we'd be in a real
mess right now we wouldn't be able to
tell the two from each other but luckily
nature has been kind and it's given us a
fairly clear signature as to what we're
seeing so we're really at the birth of a
field here as we understand the the
relation between different planets in a
planetary system and this is just the
very very beginning of of a field that's
brand new to us we we simply haven't had
the ability the power to see these very
small and dim objects in the universe
okay that front row we'll we'll try to
uh press on and get all the questions in
that we can but we'll have a heart out
here in about in eight minutes uh marcia
freeman with 21st century science and
technology magazine uh you had some
other announcement last november which
was very important relates to something
that dr boss said which was a transit of
a planet across the face of a star which
was a second confirming technique of a
planet an extrasolar planet and i'm
wondering if you could
mention what you learn additionally
about a planet
from a second confirming technique
let me just make one comment
the first and most important thing that
you learned from that was this is what
people thought they were
it was it was not a
variation in a star it was not some
completely other thing that we don't
understand
yeah i guess i would start by adding as
alan boss mentioned it's glorious in
science and it's the hallmark of science
as a human activity to have an entirely
independent technique by competitors
perhaps even
establish the reality of some physical
phenomenon which had already been
suspected by one technique so that's the
ground base that we like to operate from
various groups attacking a problem from
different directions getting the same
answer
the one thing we've learned that i think
is the most exciting about the
transiting planet is its
size its diameter we had known the mass
roughly from our wobble measurements
and we had known its orbit but we didn't
know its actual physical dimension
we now know that these planets are as
large as our own jupiter
approximately and that tells us that
they are made of gas rather than solid
of course an object that's solid would
be more compressed and smaller
and the transiting planet by virtue of
the fact that the star dims as the
planet crosses in front allows us to
measure the size of the planet and hence
determine that it's large and hence
gaseous
leonard
leonard david with space.com
um maybe jump into the future a bit
several decades listening to dan golden
he's challenged you kind of folks to uh
to image uh
continents or oceans maybe a couple
weeks ago you might have said bald spots
on aliens i don't know what but it's
certainly a challenge what do you think
uh the prospect is in your own mind the
march of technology and again these
space-based capabilities of doing that
heidi do you want to give that a yeah
well ann already gave a really nice
summary of what nasa's plans are and how
they plan to proceed
and i think that most of us
recognize that that's a great plan we
also recognize that it's a tough thing
to do i think that we all understand
that the interferometry method is the
way we have to go this is where you take
multiple telescopes and you can separate
them by great distances and yet you can
combine the signal
to give you a telescope that has the
effective area of this the difference
between the two that that's really what
we're going to need
to really be able to you know see the
continents on another planet i think
another thing that most of us believe is
feasible in the next
well why don't we say in our lifetimes
is that that's a that's probably the
right time skill here um is to use these
very large telescopes or arrays of
telescopes to measure the the chemical
signatures of what is on these planets
to to use spectroscopy
to really detect whether or not there's
ozone or methane or some other kind of
signature that is there
i think most of us think that's probably
more likely than taking
pictures of these planets
and it's going to give us more
quantitative information
about planets around other stars
but after we get a spectrum of a planet
and find out that it has ozone it's
going to be i think inevitable that
we're going to want to eventually take
the big leap and build a terrestrial
planet imager this may be 30 40 years in
the future but it's something that's
going to be an imperative for our
civilization it'll be a lot easier to do
that than it will be to build a
spacecraft to go there which we'll talk
about even farther in the future so it's
one of these
another giant steps we'll be taking and
if we know that there are earths out
there nearby we're going to want to take
a picture of them and we'll figure out a
way to do it
and just to give you a little
perspective looking backwards 15 years
when these guys were starting on this 15
years ago people laughed at them for
doing this
jeff and i have a friend in astronomy
who's got a really great test for how to
tell whether a project is worth doing
and that is you you go out to dinner
with them and you describe the science
and if they all burst out laughing then
that's a great thing to do so you know
sometimes it takes very new ideas and
these guys are working on something that
15 years ago was a joke
no maybe not quite a joke but but most
astronomers were not on the wagon that
this is a very cool stuff and you know
when we sit now and look into the future
15 or 20 years you've really got to push
your ideas
we have time for about maybe one or two
more go ahead
i just wanted to clarify you i think
jeff had said that about one-fourth of
the stars that you look at are not good
candidates for planets and out of wha
what kind of a population is that that
you've looked at altogether
uh let's see i'm not quite sure what
you're referring to
with regard to one quarter of the
stars or planets not being that was
paul's statement uh
but you know where the one quarter came
from just about one quarter of our stars
are flat they're not showing any
variation ah i see
how many stars have you looked at is
what he wants to know okay
200 500 we have right now about 1 100
stars in our sample about 500 stars
we've looked at over a long enough
period of time that we can say at least
over three or four years we're not
seeing variations our goal is to ramp up
the survey to about 2 000 stars which
will allow us to do every star within
about 150 light years and we hope to
ramp up within the next two or three
years and get every nearby star under
survey
okay unfortunately we have run out of
time we're losing the satellite and
we're going to have to
close down
you'll be available for
uh questions here in nasa headquarters
uh thank you very much for joining us
today
we
have a slate coming up here showing you
the website where you can get the images
uh and the other information from today
also information about the missions that
were discussed you can find at
the nasa website space science.nasa.gov
and we'll see you again next time thank
you very much
um