Exoplanetary Thoughts for 2010

by Paul Gilster on December 31, 2009

Several stories stick in my mind as we approach the New Year, presented here in no particular order, but merely as material for musing. The detection (by the MEarth Project) of a transiting ‘super-Earth’ this past month opens up interesting areas for speculation. Gliese 1214b is roughly 6.5 times as massive as Earth, orbiting an M-dwarf some forty light years from our Solar System. You’ll recall we discussed this one in terms of possible study of its atmosphere.

Abundant Small Worlds

On the always interesting systemic site, Greg Laughlin notes that the orbital period of this planet is a mere 1.58 days. In fact, the planet is separated from the system barycenter by 0.014 AU, which turns out to be the smallest separation yet measured for any planet. What stands out here is the density of the red dwarf. Says Laughlin: “Gliese 1214 is more than twice as dense as lead. The density of the Sun, on the other hand, is bubblegum by comparison.”

The result: a planet/star separation that isn’t quite as tight as it seems, a reminder of just how tiny M-dwarfs really are. Here’s Greg’s diagram of the system:

But what I want to focus on is what Gliese 1214b implies. In the recent post, Greg goes on to say:

Gliese 1214b lies at enough stellar radii from Gliese 1214 that its a-priori transit probability was only about 7%. The Mearth survey currently covers only ~2000 stars, and so the fact that the discovery was made so quickly was probably not luck, but rather points to the existence of a very large number of low-mass planets orbiting small stars.

Indeed, and recent trends tell us we’ll be learning a good deal more about such worlds. The MEarth Project reminds us of the viability of continuing transit surveys that will look for true Earth analogs around low-mass M-dwarfs. Is 2010 the year we’ll find such a world? The potential is there, but it’s also true that in addition to transits, our radial-velocity capabilities are being sharpened all the time. And then, of course, we have space-based missions like Kepler and CoRoT, the results of which should enliven the coming year.

Charting Nearby Brown Dwarfs

More musings: The recently launched WISE (Wide-Field Infrared Survey Explorer) satellite has jettisoned its protective cover. Up next for the 40-centimeter telescope and four infrared detector arrays is the adjustment of the spacecraft to match the rate of the onboard scanning mirror, which allows WISE to counteract the spacecraft’s motion to take ‘freeze-frame’ snapshots of the sky every eleven seconds, totaling some 7500 images per day.

Image: This is the central region of the Milky Way Galaxy as viewed in infrared light. The image is a composite of mid-infrared imagery from the MSX satellite and near-infrared imagery from the 2MASS survey. WISE images will be similar in quality. Credit: WISE/MSX/2MASS.

WISE begins its infrared survey in mid-January, and we’ll see ‘first-light’ images released to the public in about a month, after the telescope has been fully calibrated. Again we think in terms of significant discoveries within the next year, for in addition to WISE’s detection of asteroids and distant, dusty galaxies, the spacecraft has the ability to detect nearby brown dwarfs in numbers beyond anything we’ve been able to achieve before. WISE has a primary mission lasting nine months, ending when its coolant evaporates, but it’s possible that may be long enough to spot a brown dwarf closer than Alpha Centauri. At any rate, our brown dwarf catalog should be beefed up considerably.

Planetary Formation from Another Epoch

Further afield, New Scientist offers a brief comment on the work of Erin Mentuch (University of Toronto), whose analysis of the light from 88 remote galaxies, emitted when the universe was between a quarter and a half of its current age, shows what appears to be the signature of circumstellar disks. From the article:

The galaxies’ light output peaks at two distinct wavelengths. One represents the combined light of a galaxy’s stars; the other, at longer wavelengths, comes from the glow of its interstellar dust.

In each case, Mentuch noticed a faint third component between the two peaks. Whatever produces this light is too cold to be stars and too warm to be dust. The most likely source is circumstellar discs – embryonic solar systems around young stars. “It’s the most surprising result I’ve ever worked on,” says Roberto Abraham, who collaborated with Mentuch.

Perhaps not as surprising as all that, given that it fits our current model of abundant planetary formation, but useful in that it may help us get a handle on planet formation in an earlier stage of the universe’s existence. Whatever that result, we enter 2010 with great anticipation of data that may change our map of nearby space and add substantially to our catalog of exoplanets, some of which may well be similar to the Earth. From Kepler, CoRoT and WISE to sharpened detection methods here on Earth, the golden age of planetary detection continues and, if we’re lucky, 2010 may just be the year we find a planet around Centauri A or B. Plenty to muse upon in all this, and plenty of excitement building for the New Year.

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Didac December 31, 2009 at 13:12

A very interesting diagram. You can see how close this planet is from its star. You can see a simmilar diagram for our Earth-Sun system:

http://www.spudart.org/earthsun/

Even the Earth-Moon system is not so “dense”:

http://commons.wikimedia.org/wiki/File:Earth_Moon_Scale.jpg

Mike December 31, 2009 at 14:09

Yes,it should be quite a year!
I wouldn’t be too surprised if there is a big annoucement from the Kepler team at the AAS meeting in Washington next week.
If you look at the Keck 1 observing schedule through the late summer and fall of 2009 you’ll notice there have been a number of observing runs paid by NASA and used by some of the Kepler astronomers utilizing the HIRES
instrument as they do follow-up on their detected transits using the radial velocity method.
They’ve had enough time to view multiple transits around M-Dwarfs in the HZ and whether or not they have been able to confirm low mass or Earth mass planets by now I think we will find out very soon.
Kepler’s target stars include (to the best of my knowledge) about 3000 M-Dwarfs and about 25,000 K-Dwarfs.
That should give us a pretty good chance for earlier 3 transit detections then the 3 years or so needed for G-Dwarf stars if we are considering habitable zone and not wider orbits. Ofcourse hot orbits would be even sooner.
So I think it is quite possible that Earth like planets have already been detected and possibly verified already so I’m guessing that there will be a
BIG annoucement this Monday at the AAS meeting.
Well,here’s hoping and Happy New Year to everybody!

MaDeR December 31, 2009 at 22:18

Well, no. First announcement (January 2010) will be about easy targets: hot jupiters and alike. Wanna bet? :>

“So I think it is quite possible that Earth like planets have already been detected”
Yes and no. Yes as in “they are hidden in Kepler data” (should be a few transits for each of short-period 1Me planet in hab zone after six months of observation). No as in “we analysed data from Kepler and know it”.

“and possibly verified already”
Almost certainly not. Do you have unrealistic expectations often, as most of folks here?

“I’m guessing that there will be a BIG annoucement this Monday at the AAS meeting.”
Impeding really big announcement = chock-full of rumours flying in all directions. This kind of thing would be almost impossible to successfully embargoed.

Adam January 1, 2010 at 5:53

Will be quite a year of surprises I’m hoping.

Horatius January 1, 2010 at 8:34

big annoucement or not from Kepler on Monday, they must certainly have something important to announce as they named it “The Big Reveal” ?(http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=15). I would wager that the number of hot jupiters will jump up dramaticly. Some hot super-earths are also probable. They should also claim something on the relative frequency of hot jupiters in the Galaxy. We will see… I am impatiant a little bit, and You?

Terraformer (a.k.a Tobias Holbrook) January 1, 2010 at 13:31

I must admit, I’m more excited by WISE than Kepler. Finding a colonizable target much closer than aCentauri would be much more of a boon than a habitable planet 11ly away around Eridani.

But that might be because I enjoy terraforming…

Dave January 1, 2010 at 14:01

I read an article in which the Kepler project director said what they’ve found in the data so far is so stunning that it will “knock your socks off” when they reveal it, assuming it’s later verified.

andy January 1, 2010 at 16:56

Dave: maybe, but the really interesting stuff is not necessarily what will be announced in the upcoming meeting. I’m predicting that the solid candidates being announced will be a bunch of hot Jupiters, but there will likely be hints of unconfirmed stuff that will take longer to announce.

The results for the previously-known planets in the Kepler field may also be significant. For starters, the TrES-2 exoplanet may be undergoing orbital parameter changes – it will be interesting to see whether Kepler confirms this: if so this would be the first confirmed detection of orbital parameter variations in a transiting planet, though perhaps the duration of the Kepler observations isn’t sufficient yet.

philw1776 January 1, 2010 at 20:10

Word up is that they discovered numerous hot white dwarf companions that are much smaller than models and previous observations have revealed. A new class of objects.

As to habitable and terrestrial planets, I’m not expecting anything this soon.

Phil January 1, 2010 at 22:34

I’m with Terraformer on this one. WISE is tremendously exciting. Any nearby brown dwarf would instantly get planners thinking about a doable interstellar mission buzzing. Plus the BD might have a planetary system of its own!

All in all a really exciting year to come.

P

ljk January 3, 2010 at 0:04

Molecular astronomy of cool stars and sub-stellar objects

Authors: Peter F. Bernath

(Submitted on 27 Dec 2009)

Abstract: The optical and infrared spectra of a wide variety of `cool’ astronomical objects including the Sun, sunspots, K-, M- and S-type stars, carbon stars, brown dwarfs and extrasolar planets are reviewed.

The review provides the necessary astronomical background for chemical physicists to understand and appreciate the unique molecular environments found in astronomy. The calculation of molecular opacities needed to simulate the observed spectral energy distributions is discussed.

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Journal reference: International Reviews in Physical Chemistry 28, 681 (2009)

Cite as: arXiv:0912.5085v1 [astro-ph.SR]

Submission history

From: Peter Bernath [view email]

[v1] Sun, 27 Dec 2009 15:51:10 GMT (4479kb)

http://arxiv.org/abs/0912.5085

ljk January 3, 2010 at 0:35

The current population of benchmark brown dwarfs

Authors: A.C. Day-Jones, D.J. Pinfield, M.T. Ruiz, B. Burningham, Z.H. Zhang, H.R.A. Jones, M.C. Galvez-Ortiz, J. Gallardo, J.R.A. Clarke, J.S. Jenkins

(Submitted on 29 Dec 2009)

Abstract: The number of brown dwarfs (BDs) now identified tops 700. Yet our understanding of these cool objects is still lacking, and models are struggling to accurately reproduce observations. What is needed is a method of calibrating the models, BDs whose properties (e.g. age, mass, distance, metallicity) that can be independently determined can provide such calibration.

The ability to calculate properties based on observables is set to be of vital importance if we are to be able to measure the properties of fainter, more distant populations of BDs that near-future surveys will reveal, for which ground based spectroscopic studies will become increasingly difficult. We present here the state of the current population of age benchmark brown dwarfs.

Comments: 2 pages, 1 figure, to appear in the conference proceedings “New Technologies for Probing the Diversity of Brown Dwarfs and Exoplanets”, Shanghai, 19-24 July, 2009

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)

Cite as: arXiv:0912.5339v1 [astro-ph.SR]

Submission history

From: Avril Day-Jones Miss [view email]

[v1] Tue, 29 Dec 2009 17:33:16 GMT (24kb)

http://arxiv.org/abs/0912.5339

david lewis January 3, 2010 at 9:36

2010 might be the year that alpha centauri loses its place as our closest stellar neighbor should WISE find a close brown dwarf. How humbling that should be for us humans – we know so little of the cosmos that we can’t even be sure if there’s a solar system closer to us than alpha centauri. Very humbling.

exofever January 3, 2010 at 18:32

The big reveal could be that they have found a LARGE number of detections of small transiting objects. From page 16 of the PLATO assessment study report:

“…by very recent
detections with the Kepler satellite of a large population of close-in, small transiting objects (2 – 4 Earthradii, private communication) awaiting to be confirmed by radial velocity observations.”

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=46020

Administrator January 3, 2010 at 18:57

Good catch, exofever!

david lewis January 4, 2010 at 8:39

===========
The big reveal could be that they have found a LARGE number of detections of small transiting objects. From page 16 of the PLATO assessment study report:
===========

Could kelper find evidence of technological aliens? Imagine immense solar arrays orbiting very close to a star. Objects thousands of kilometers in diameter that can be detected by it, yet don’t cause the star to wobble.

Barring the use of some method of total conversion of mass into energy, which I think would be the more likely scenario, such arrays could provide an alien civilization with an immense amount of energy.

Ronald January 5, 2010 at 8:23

Happy new year everybody! May we all witness the revelation of many more newly discovered exoplanets.

With regard to Mentuch’s work (analysis of the light from 88 remote galaxies, showing what appears to be the signature of circumstellar disks), I was wondering: it should be possible in this fashion, to do similar and comparative analysis for different types of galaxies, in particular spiral compared with elliptical galaxies. There has been some discussion whether elliptical galaxies are suitable at all for planetary formation (mainly old, low metallicity stars, etc.).
Such an analysis might give an indication of that.

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