Extrasolar Planetology

Sulfur seas, lakes or rivers in Venus.

Diakonov — Thu, 29 Oct 2009 19:47:57 GMT

In a topic in extraterrestrial forum, I talked about the possibility of life on Venus. This time, I'll discuss the possibility of having liquid sulfur (in order to have life there, if possible on a sulfur solution). Venus has an atmosphere rich in sulfur gases and CO2. If there's so many sulfur in the air (clouds of sulfur compounds), then I guess it would be possible to have at least small lakes of sulfur in some areas. I'm guessing that because we only have radar images and such images ...

Study on Eps Indi Ba and Bb

Sirius_Alpha — Wed, 18 Nov 2009 04:43:33 GMT

Epsilon Indi Ba, Bb: a detailed study of the nearest known brown dwarfs http://arxiv.org/abs/0911.3143 Abstract wrote:The discovery of epsilon Indi Ba, Bb, a binary brown dwarf system very close to the Sun, makes possible a concerted campaign to characterise the physical parameters of two T dwarfs. Recent observations suggest substellar atmospheric and evolutionary models may be inconsistent with observations, but there have been few conclusive tests to date. We therefore aim to characterise ...

Giant planet interiors

Sirius_Alpha — Wed, 18 Nov 2009 04:42:31 GMT

Giant Planet Interior Structure and Thermal Evolution http://arxiv.org/abs/0911.3154 Abstract wrote:We discuss the interior structure and composition of giant planets, and how this structure changes as these planets cool and contract over time. Here we define giant planets as those that have an observable hydrogen-helium envelope, which includes Jupiter-like planets, which are predominantly H/He gas, and Neptune-like planets which are predominantly composed of elements heavier than H/He. ...

Secondary eclipse of HAT-P-1 from Spitzer

Sirius_Alpha — Thu, 12 Nov 2009 02:16:38 GMT

Spitzer IRAC Secondary Eclipse Photometry of the Transiting Extrasolar Planet HAT-P-1b http://arxiv.org/abs/0911.2218 Abstract wrote:We report Spitzer/IRAC photometry of the transiting giant exoplanet HAT-P-1b during its secondary eclipse. This planet lies near the postulated boundary between the pM and pL-class of hot Jupiters, and is important as a test of models for temperature inversions in hot Jupiter atmospheres. We derive eclipse depths for HAT-P-1b, in units of the stellar flux, that ...

H20, CH4, CO2 at HD 209458 b

Sirius_Alpha — Wed, 07 Oct 2009 08:48:54 GMT

Water, methane, and carbon dioxide present in the dayside spectrum of the exoplanet HD 209458 b http://www.iop.org/EJ/abstract/0004-637X/704/2/1616 Abstract wrote:ABSTRACT. Using the NICMOS instrument on the Hubble Space Telescope, we have measured the dayside spectrum of HD 209458b between 1.5 and 2.5 μm. The emergent spectrum is dominated by features due to the presence of methane (CH4) and water vapor (H2O), with smaller contributions from carbon dioxide (CO2). Combining this near-infrared ...

Exotic atmosphere for CoRoT-7b predicted

exoplanet — Thu, 01 Oct 2009 22:22:08 GMT

http://www.sciencedaily.com/releases/2009/09/090930165038.htm

Exoplanet Chemistry

Sirius_Alpha — Tue, 06 Oct 2009 00:13:50 GMT

Exoplanet Chemistry
http://arxiv.org/abs/0910.0811

Abstract wrote:The characteristic chemistry of terrestrial planets and, in particular, of giant planets rich and poor in He and H2 are described.

More on EGP spectra

Lazarus — Mon, 05 Oct 2009 22:03:45 GMT

arXiv: Giant Planet Atmospheres and Spectra, discussing effect of various properties on the spectra/clouds of giant planets. For a Jupiter-mass planet at 5 Gyr, water clouds are expected beyond 1.5 AU, ammonia clouds beyond 4.5 AU.

No inversion layer for TrES-3b

Sirius_Alpha — Wed, 30 Sep 2009 13:21:41 GMT

The Broadband Infrared Emission Spectrum of the Exoplanet TrES-3 http://arxiv.org/abs/0909.5221 abstract wrote:We use the Spitzer Space Telescope to estimate the dayside thermal emission of the exoplanet TrES-3 integrated in the 3.6, 4.5, 5.8, and 8.0 micron bandpasses of the Infrared Array Camera (IRAC) instrument. We observe two secondary eclipses and find relative eclipse depths of 0.00346 +/- 0.00035, 0.00372 +/- 0.00054, 0.00449 +/- 0.00097, and 0.00475 +/- 0.00046, respectively in the ...

Planetary spectra

Lazarus — Wed, 16 Sep 2009 18:44:05 GMT

This might be of interest... 3 general classes of planetary spectra, "soil", "ice", "gas". Not all spectra get assigned to what you'd expect... Ganymede ends up in the "soil" class for example, despite the surface being icy.

Differentiating between a Venus-like atmosphere and an ice planet is an interesting problem.

Models of Neptune-mass planets: fluxes and albedos

Sirius_Alpha — Mon, 14 Sep 2009 00:31:14 GMT

Models of Neptune-Mass Exoplanets: Emergent Fluxes and Albedos http://arxiv.org/abs/0909.2043 Abstract wrote:There are now many known exoplanets with Msin(i) within a factor of two of Neptune's, including the transiting planets GJ436b and HAT-P-11b. Planets in this mass-range are different from their more massive cousins in several ways that are relevant to their radiative properties and thermal structures. By analogy with Neptune and Uranus, they are likely to have metal abundances ...

HD209458 saved from evaporation by magnetic field

exoplanet — Fri, 04 Sep 2009 18:34:18 GMT

http://www.skyandtelescope.com/news/home/56620682.html

Metallicity and galactocentric distance?

Sirius_Alpha — Fri, 28 Aug 2009 13:22:01 GMT

On this Centauri-dreams post, http://www.centauri-dreams.org/?p=9226 , it is suggested that the metallicity correlation for gas planet formation may be related to the distance a star is from the galactic centre. Older stars may have migrated inward toward the galactic centre.

8 Micrometre phase variation of HD 149026 b

Sirius_Alpha — Mon, 17 Aug 2009 03:45:19 GMT

The 8 Micron Phase Variation of the Hot Saturn HD 149026b http://arxiv.org/abs/0908.1977 Abstract wrote:We monitor the star HD 149026 and its Saturn-mass planet at 8.0 micron over slightly more than half an orbit using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We find an increase of 0.0227% +/- 0.0066% (3.4 sigma significance) in the combined planet-star flux during this interval. The minimum flux from the planet is 45% +/- 19% of the maximum planet flux, corresponding ...

Gliese 581d: not hypervolcanic

Lazarus — Wed, 10 Jun 2009 18:04:35 GMT

Tidal Limits to Planetary Habitability - apparently Gliese 581d does not experience enough tidal heating to drive plate tectonics. Of course this does not rule out volcanism from radiogenic heating, but it does mean that the planet is not an Io-style hellworld.

Shape of Hot Jupiters

Sirius_Alpha — Wed, 15 Jul 2009 11:50:04 GMT

Whenever I consider a hot Jupiter, I think of a spherical world. More spherical than that gas planets of our solar system due to a tidally slowed rotation period. Doing an image search on HD 209458 b, I found this interesting picture. From here. Could the planet be shaped like that? What about other bloated planets like TrES-4 b?

Smashing up super-Earths

Lazarus — Fri, 03 Jul 2009 21:55:58 GMT

Collisional Stripping and Disruption of Super-Earths

Simulations of what happens in the late stages of terrestrial planet formation, to see what happens to the bulk composition of the planet when you hit it with another planet. Apparently making super-Mercuries is quite difficult.

HD 80606b Spin-orbit misalignement

Sirius_Alpha — Mon, 29 Jun 2009 00:24:21 GMT

Spin-orbit misalignement for the transiting planet HD 80606b http://arxiv.org/abs/0906.4904 Abstract wrote:A global Markov Chain Monte Carlo analysis of published eclipse photometry and radial velocities is presented for the transiting planet HD 80606b. Despite the lack of a complete transit light curve, the size of the planet is measured with a good level of precision (R_p = 1.04 +0.05-0.09 R_Jup), while the orbital parameters are refined. This global analysis reveals that the orbital axis ...

Sulphur-cycle dominated planets

Lazarus — Fri, 12 Jun 2009 17:12:25 GMT

A paper on detecting whether terrestrial planets are dominated by the carbon cycle or the sulphur cycle. Sulphur cycle involves eruption of SO₂ and H₂S, and sulphur removed from the atmosphere as precipitation of sulphites, or photochemical activity. Might be more common on volcanically-active, dry super-earths.

Weak temperature inversion in XO-2b?

Sirius_Alpha — Tue, 09 Jun 2009 00:09:53 GMT

Detection of Thermal Emission of XO-2b: Evidence for a Weak Temperature Inversion http://arxiv.org/abs/0906.1293 Abstract wrote:We estimate flux ratios of the extrasolar planet XO-2b to its host star XO-2 at 3.6, 4.5, 5.8 and 8.0 micron with IRAC on the Spitzer Space Telescope to be 0.00081 +- 0.00017, 0.00098 +- 0.00020, 0.00167 +- 0.00036 and 0.00133 +- 0.00049, respectively. The fluxes provide tentative evidence for a weak temperature inversion in the upper atmosphere, the precise nature ...

ARXIV papers on Earthlike exoplanets

Mongo — Mon, 18 May 2009 20:17:48 GMT

Hello all, this is my fist post to this board, which I found out about just recently. Being interested in exoplanets, I have been keeping a list of ARXIV papers concerning them, which currently contains more than 800 titles. It seems likely to me that others might be interested in these papers as well, so I would like to start presenting titles from that list here, sorted by topic. To begin with, here is the list of papers related to Earthlike exoplanets. Once I get some feedback, including ...

PSR B1257+12 D: extrasolar dwarf planet?

NuclearVacuum — Thu, 18 Sep 2008 16:21:57 GMT

Now that the Solar system contains five dwarf planets, I would like to bring up an opinion poll on PSR B1257+12 D. Because of its mass and presumable size, should this planet be classified as the first "extrasolar dwarf planet"? I do mean should we use this definition if the planet is confirmed.

Bulk Composition of GJ 436 b

Sirius_Alpha — Tue, 21 Apr 2009 00:08:16 GMT

Bulk composition of the transiting hot Neptune around GJ 436 http://arxiv.org/abs/0904.2979 Abstract wrote:The hot Neptune orbiting around GJ 436 is a unique example of an intermediate mass planet. Its close-in orbit suggests that the planet has undergone migration and its study is fundamental to understanding planet formation and evolution. As it transits its parent star, it is the only Neptune-mass extrasolar planet of known mass and radius, being slightly larger and more massive than Neptune ...

XO-3b spin-orbit misalignment not as bad as thought.

Sirius_Alpha — Mon, 23 Feb 2009 01:15:38 GMT

The Spin-Orbit Misalignment of the XO-3 Exoplanetary System http://arxiv.org/abs/0902.3461 Abstract wrote:We present photometric and spectroscopic observations of the 2009 Feb. 2 transit of the exoplanet XO-3b. The new data show conclusively that the planetary orbital axis and stellar rotation axis are misaligned. We thereby confirm the previous finding by Hebrard and coworkers, although we find a significantly smaller angle (37.3 +/- 3.7 deg) between the sky projections of the two axes. ...

dM star planets and cosmic rays

Lazarus — Fri, 06 Feb 2009 23:35:46 GMT

On the protection of extrasolar Earth-like planets around K/M stars against galactic cosmic rays

Planets in the habitable zones of dM stars are not so well protected against cosmic rays because the magnetic moment is reduced thanks to tidal locking. Making the planet more massive does not do much to help the situation either, as the larger radius means the planetary atmosphere is located at a larger distance.

Good news for Gliese 581c, bad news for d?

Lazarus — Sat, 07 Feb 2009 11:37:04 GMT

From http://www.tat.physik.uni-tuebingen.de/~fgp/Conf09/abstractbooklet.pdf - abstract titled "Extrasolar planets in the Gliese 581 system � Model Atmospheres and Implications for Habitability" The conclusions presented seem to imply that liquid water is possible on Gliese 581c, but Gliese 581d would be too cold to support life, a conclusion which goes against the previous studies of the system.

V391 Peg is a hybrid pulsator

Sirius_Alpha — Thu, 29 Jan 2009 01:24:18 GMT

The planet-hosting subdwarf B star V391 Pegasi is a hybrid pulsator http://arxiv.org/abs/0901.4523 Abstract wrote:A noticeable fraction of subdwarf B stars shows either short-period (p-mode) or long-period (g-mode) luminosity variations, with two objects so far known to exhibit hybrid behaviour, i.e. showing both types of modes at the same time. The pulsating subdwarf B star V391 Pegasi (or HS2201+2610), which is close to the two known hybrid pulsators in the log g - Teff plane, has recently ...

HD 40307: mini-Neptunes?

Lazarus — Wed, 14 Jan 2009 10:59:34 GMT

The HD 40307 Planetary System: Super-Earths or Mini-Neptunes?
Consideration of tides seems to favour the mini-Neptunes scenario rather than super-Earths. Possibilities for the inner planet b also include a volcanic "super-Io" or the core of an eroded Neptune-type planet.

OGLE 2007-BLG-192 b ... 1.4 M_e?

Sirius_Alpha — Mon, 19 Jan 2009 00:57:25 GMT

Does anyone know anything about this?
http://www.newscientist.com/article/dn16439-smallest-known-planet-may-actually-be-earthmass.html

Or is the article optimistically speculating?

Constraints on HD 189733 b radio emissions.

Sirius_Alpha — Mon, 19 Jan 2009 01:06:02 GMT

Secondary radio eclipse of the transiting planet HD 189733 b: an upper limit at 307-347 MHz http://arxiv.org/abs/0901.2344 abstract wrote:We report the first attempt to observe the secondary eclipse of a transiting extra-solar planet at radio wavelengths. We observed HD 189733 b with the Robert C. Byrd Green Bank Telescope of the NRAO over about 5.5 hours before, during and after secondary eclipse, at frequencies of 307 - 347 MHz. In this frequency range, we determine the 3-sigma upper limit ...

Brown Dwarfs... what's with them?

NuclearVacuum — Tue, 23 Dec 2008 22:51:40 GMT

I already know what a brown dwarf is, but I just don't get them. Why are we mentioning them on Extrasolar Visions? What is it with them that makes them just as interesting as extrasolar planets? Are they interesting because they can harbor moons (maybe Earth-like moons)? I am very puzzled at this, and I am open to anything, so can you please help me out?

How to build HD 149026b with its massive core

Lazarus — Wed, 07 Jan 2009 14:15:55 GMT

Discovering the Growth Histories of Exoplanets: The Saturn Analog HD 149026b

Seems that the way to build the Saturn-mass planet HD 149026b is to start the planet at roughly Saturn's distance from the star and have it migrate inwards through a disc with roughly 2 times the amount of solids as the solar nebula had. This results in the formation of the planet's massive core as it migrates.

Fluorine-Rich Planet (Probable?)

marasama — Sat, 20 Dec 2008 05:35:10 GMT

Is Fluorine-rich planets, probable? So, Fluorine is not produced enough in the universe, based on observations of the visible universe. So, the next bet is to find a place where fluorine is produced in over solar abundance. Locations: 1a) Wolf-Rayet stars can shed large amounts of their atmosphere. Fast enough that fluorine escapes before it is annihilated. Probably unlikely to orbit a WR star due to the strong solar winds. 1b) A secondary low/intermediate-mass star orbiting the WR ...

Expanding the HR diagram to include planets

marasama — Mon, 08 Dec 2008 04:01:02 GMT

Just thinking on how it would look. So you got the alphabets. ABCDEFGHIJKLMNOPQRSTUVWXYZ Stars & brown dwarfs are: W OBAFGKML TY wD Carbon Stars CNR S J Problematic letters: IQUVXZ You are left with: EHP H = For giant planets, sort of like the Hydrogen Dwarfs E = Earth-like, Terrestrial. Yeah, it says it is problematic, but it is not a galaxy. Any thoughts? Reference: http://www-int.stsci.edu/~inr/ldwarf1.html

Ocean Worlds

marasama — Mon, 15 Dec 2008 06:15:57 GMT

Just trying to think up of different types of oceans on other worlds. The list I came up with is: HOT 1) Molten iron/iron-nickel mix 2) Heavy Water mix, ie. Maybe on Venus at one time... 3) Hot oceans of water mix, usually would be on more massive planets with denser atmospheres. 4) Molten sulfur water mix, is possible, pockets of molten sulfur has been found at the bottom of the ocean. The pockets displace the water to be nearly sulfur. WARM 1) Salt ocean (sodium chloride), ie. ...

Planets within 10 Parsecs

youknowandy — Wed, 03 Dec 2008 07:39:19 GMT

HD 17156 b characterization, & no stellar companions 150-1000 AU.

Sirius_Alpha — Thu, 04 Dec 2008 01:34:29 GMT

Characterization of the HD 17156 planetary system http://arxiv.org/abs/0812.0785 Abstract wrote:AIMS : To improve the parameters of the HD 17156 system (peculiar due to the eccentric and long orbital period of its transiting planet) and constrain the presence of stellar companions. METHODS : Photometric data were acquired for 4 transits, and high precision radial velocity measurements were simultaneously acquired with SARG@TNG for one transit. The template spectra of HD 17156 was used to ...

upsilon And b is an oddball ?

exoplanet — Thu, 27 Nov 2008 23:57:09 GMT

Hi, I have been trying to find some more info on upsilon And b regarding the supposed large temperature gradients between the day and night sides of the planet observed by Spitzer a few years ago.This seems to be atypical (unique as far as I know) of other hot Jupiters, which apparently are very efficient at redistributing heat in the atmosphere. Have these observations been confirmed ? The fit to the data points seemed like a bit of a stretch to me: http://www.centauri-dreams.org/wp-content/uploads/2006/10/upsilon_andromedae_b.jpg Any ...

HD 3346's companions

marasama — Mon, 01 Dec 2008 03:52:38 GMT

If people remember asking J.Whatmough on where he got that companion for HD 3346, well, I found it.
http://www.extrasolar.net/planettour.asp?StarCatID=normal&PlanetID=90

The paper.
HD 3346

HD 17156 b atmosphere characteristics

Sirius_Alpha — Mon, 01 Dec 2008 01:06:10 GMT

The Upper Atmosphere of HD17156b http://arxiv.org/abs/0811.4751 Abstract wrote:HD17156b is a newly-found transiting extrasolar giant planet (EGP) that orbits its G-type host star in a highly eccentric orbit (e~0.67) with an orbital semi-major axis of 0.16 AU. Its period, 21.2 Earth days, is the longest among the known transiting planets. The atmosphere of the planet undergoes a 27-fold variation in stellar irradiation during each orbit, making it an interesting subject for atmospheric modelling. ...

Planetary Masses - 3rd attempt

marasama — Mon, 07 Jul 2008 04:09:44 GMT

TYPEMASS Brown Dwarf if [Fe/H] > 0, then ~13 to ~65Mj if [Fe/H] = 0, then ~13 to ~80Mj if [Fe/H] < 0, then ~13 to ~80-90Mj Transitional Planets Mass between 12-14Mj, due to metallicity Gray-area between planet & sub-brown dwarf Mass at ~5 to 12Mj Electron degeneracyBegins at ~2MjMetallic hydrogenBegins at ~0.1Mj / 31.8MeAbility to start accreting gas Begins at ~7-15Me Ability to maintain volatile? Ability to maintain a tenuous atmosphere? Any suggestions/criticisms ...

Planet Classification - Temperature Range

marasama — Mon, 03 Nov 2008 05:53:53 GMT

Again, trying to mimic the stellar classification. # Description 0-0.5 3000K+, this would place it in the hotter dM regime. 1-1.5 2500K, this would place it in the dM8-9 spectra. Probably irradiated planets and irradiated protoplanets. 2-2.5 1300K, this would place it in the dL spectra. 3-3.5 ~900K 4-4.5 ~700K, beginning of the dT spectra. Possibly the temp when Jupiter was a protoplanet, based on an AJ paper, (sorry, no links). 5-5.5 ~350K 6-6.5 ~275K, mean Earth temp. ...

Two classes of hot Jupiter a statistical artefact?

Lazarus — Sun, 23 Nov 2008 22:44:51 GMT

It is starting to look like the classification of hot Jupiters according to Safronov number isn't holding up too well: the division between the two categories may have been a statistical artefact.

arXiv: Homogeneous studies of transiting extrasolar planets. II. Physical properties

Icy planets common around A-type stars

Sirius_Alpha — Tue, 15 Jul 2008 03:36:33 GMT

A Spitzer Study of Debris Disks In The Young Nearby Cluster NGC 2232: Icy Planets Are Common Around ~ 1.5--3 Solar-Mass Stars http://arxiv.org/abs/0807.2056 Abstract wrote:We describe Spitzer IRAC and MIPS observations of the nearby 25 Myr-old open cluster NGC 2232. Combining these data with ROSAT All-Sky Survey observations, proper motions, and optical photometry/spectroscopy, we construct a list of highly probable cluster members. We identify 1 A-type star, HD 45435, with definite excess ...

List of requirements for being a planet (WIP) - help please

marasama — Sat, 15 Nov 2008 23:38:39 GMT

This will be a list of items that will qualify it being a planet. No arbitrary stats, of course.

Polarized light from HD 189733 b? Maybe not?

Sirius_Alpha — Sat, 15 Nov 2008 03:55:52 GMT

Non-Detection Of Polarized, Scattered Light From The HD 189733b Hot Jupiter Link Abstract wrote:Using the POLISH instrument, I am unable to reproduce the observations of Berdyugina et al. (2008), who claim to have detected polarized, scattered light off the atmosphere of the HD 189733b hot Jupiter. The amplitude of this signal is reported to be two parts in 10^4, which is larger than twice the amplitude expected for a perfectly diffusing, Lambertian planet. However, Lucas et al. (2008) find ...

Extrasolar terrestrial planets are carbon-poor

Lazarus — Wed, 12 Nov 2008 11:51:14 GMT

Six White Dwarfs with Circumstellar Silicates

The material from the disrupted asteroids orbiting these white dwarfs is poor in carbon, which suggests extrasolar terrestrial planets typically form from carbon-poor material. So much for carbon planets?

Astrometric determination of exoplanet masses.

Sirius_Alpha — Thu, 04 Sep 2008 22:12:40 GMT

Exoplanet Masses from HST/FGS Astrometry - Progress Report Link Abstract wrote:We present a progress report on our ongoing efforts to produce actual exoplanet masses (as opposed to M sin i). We obtain masses through astrometry of host star perturbations. The Fine Guidance Sensors aboard Hubble Space Telescope provide millisecond of arc per observation precision. Our five targets include HD 38529, HD 47536, HD 136118, HD 145675, and HD 168443. Specific results presented at this meeting will ...

HD 28185 and new Hipparcos data reduction: bad news?

Lazarus — Tue, 15 Jul 2008 20:20:06 GMT

There's a new reduction of the Hipparcos catalogue available online here... I wondered if this would result in a change in the habitable status of the planet HD 28185... Working with visual magnitudes only (this is probably ok, since the Sun and HD 28185 have similar spectral types) Taking Sol's habitable zone as 0.95-1.15 AU (from here) Apparent magnitude = 7.81 (SIMBAD) HD 28185: old parallax = 25.28 � 1.08 mas Absolute magnitude = 4.82 � 0.09 Luminosity = 1.01 � 0.04 solar Habitable ...

Forming ring systems

Lazarus — Sat, 11 Oct 2008 17:58:55 GMT

Did Saturn's rings form during the Late Heavy Bombardment ? A hypothesis that attempts to explain why Saturn has a massive ring system and the other giant planets don't. Basic idea is that a Mimas-sized moon migrated inside the Roche limit and was destroyed by a large impact during the Late Heavy Bombardment. The alternative scenario, formation by disruption of large comets, suffers from the problem that Saturn is the giant planet expected to receive the least amount of such material, which ...