Possible image of an exoplanet next to Beta Pictoris

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Possible image of an exoplanet next to Beta Pictoris

Post by Stalker on 21st November 2008, 7:24 am

Maybe the Very Large Telescope shoot a photography of an exoplanet around Beta Pictoris.

In french
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Lazarus on 21st November 2008, 7:56 am

If confirmed, this is great... the ~10 AU proposed planet around Beta Pictoris is one of the more secure planets inferred from dust discs, as there are several independent lines of evidence which suggest a planet should be there.

Guess we need to wait for orbital motion to be detected - fortunately the orbital period (probably in the range 20-30 years) is much shorter than the HR 8799 planets, and especially Fomalhaut b, though I'd guess if it is edge-on (like the disk) it will be harder to come up with a definitive orbit for the reason you would only see 1 dimension of the orbital motion.

For the non-Francophones among you, try this link (from which you can also get a copy of the paper in pdf format)
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Edasich on 21st November 2008, 9:29 am

So this Autumn seems a hot season for Exoplanet imaging detection Smile

Next target is Vega and AU Microscopii (among the nearest proplyd-hosts)
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Sirius_Alpha on 21st November 2008, 2:15 pm

A Physorg article claims a distance of 8 AU. That can't be right? Exoplanet imaged around A-type star, 70 ly away from Earth, 8 AU from star? Lazarus said 10 AU. That's also close.

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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Lazarus on 21st November 2008, 2:24 pm

Projected separation is 411 milliarcseconds, which at Beta Pictoris's distance is 8 AU. The predicted semimajor axis from dust disc modelling is ~10 AU.
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Edasich on 21st November 2008, 2:45 pm

EPE lists it amongst Candidates detected by imaging:

http://exoplanet.eu/star.php?st=beta+Pic
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Sirius_Alpha on 21st November 2008, 4:50 pm

Wait... Bet Pic b is confirmed?

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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Edasich on 22nd November 2008, 6:21 am

Sirius_Alpha wrote:Wait... Bet Pic b is confirmed?

Likely. Smile
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by NuclearVacuum on 22nd November 2008, 11:54 am

Oh my, its only a matter of time until the planet of Vega is found =D
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Sirius_Alpha on 22nd November 2008, 11:57 am

Edasich wrote:Likely
Cool!. EPE shows it as confirmed, press release says "Possible image" and such. Still though, what else could it be? Right next to Beta Pictoris, and in line with the protoplanetary disk. It's got to be a planet. I would be immensely surprised if it turns out to be a background star.

Nuclear Vacuum wrote:Oh my, its only a matter of time until the planet of Vega is found =D
Bring it! Finally, all of these protoplanetary disk systems which have been suspected of hosting planets are now finally yielding confirmations. I've never seen a good image of the Vega disk, but the system is face-on, so I'm not sure what I should expect.

EPE lists Beta Pictoris b as having an orbital period of 16 days.



An 8 Jupiter-mass planet at 8 AU is inconsistent with the most recent model of the Beta Pictoris system disk morphology.

Planets of Beta Pictoris revisited
http://arxiv.org/abs/astro-ph/0701526

Florian Freistetter et al. wrote:Observations have revealed a large variety of structures (global asymmetries, warps, belts, rings) and dynamical phenomena ("falling-evaporating bodies" or FEBs, the "Beta Pic dust stream") in the disc of Beta Pictoris, most of which may indicate the presence of one or more planets orbiting the star. Because planets of Beta Pic have not been detected by observations yet, we use dynamical simulations to find "numerical evidence" for a planetary system. We show that already one planet at 12 AU with a mass of 2 to 5 Mjup and an eccentricity smaller or equal 0.1 can probably account for three major features (main warp, two inner belts, FEBs) observed in the Beta Pic disc. The existence of at least two additional planets at about 25 AU and 45 AU from the star seems likely. We find rather strong upper limits of 0.6 Mjup and 0.2 Mjup on the masses of those planets. The same planets could, in principle, also account for the outer rings observed at 500 - 800 AU.


Freistetter et al. claim a 2-5 M_j planet at 12 AU, 0.6 M_j planet at 25 AU, and 0.2 M_j planet at 45 AU. Could the 8 Jupiter-mass planet imaged here be the 2-5 M_j planet proposed by Freistetter et al? And if so, what might this mean for the other two possible planets in the system?


Also, an 8 Jupiter-mass planet orbiting a 1.8 Solar-mass star at 8 AU would produce a 60 m RV signal at 90 degrees inclination.

As for the planet being confirmed, I found this.
“We cannot yet rule out definitively, however, that the candidate companion could be a foreground or background object. To eliminate this very small possibility, we will need to make new observations that confirm the nature of the discovery.”

AFAIK, HST hasn't ever seen a background star near Beta Pictoris. But the best image I know of is this one,

in which the occulter would hide it anyway.

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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Edasich on 22nd November 2008, 3:43 pm

Thus two more planets may be detected and confirmed soon.
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Sirius_Alpha on 22nd November 2008, 4:25 pm

That would be nice, but I wouldn't count on it. The proposed masses of those other two seem pretty low.

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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Edasich on 22nd November 2008, 4:33 pm

Sirius_Alpha wrote:That would be nice, but I wouldn't count on it. The proposed masses of those other two seem pretty low.

Well who knows? Accounting their relative youths, radii may appear a bit bloated and thus as glowing as other protoplanets. alien
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Sirius_Alpha on 22nd November 2008, 8:11 pm

Compared to a 8 M_j planet, how much does a sub-Jovian-mass planet heat up when it's formed?

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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Edasich on 23rd November 2008, 5:55 am

Sirius_Alpha wrote:Compared to a 8 M_j planet, how much does a sub-Jovian-mass planet heat up when it's formed?

Ask Lazarus. He surely knows haha Razz
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Lazarus on 23rd November 2008, 1:40 pm

Far as I know, initial conditions are a bit of an unknown. Probably going to be smaller and cooler than a more massive gas giant I'd guess.

One question that is slightly worrying about these evolutionary model predictions of masses is how much these planets are still getting hit by debris in the system. A post-collision object could masquerade as a higher-mass planet.
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Sirius_Alpha on 23rd November 2008, 1:46 pm

Continued monitoring should help constrain the true nature of the object, right? If Beta Pictoris b fades away, then it was some, relatively, low-mass object getting whacked by a planetesimal, right? I'm sure this happens often in such protoplanetary systems, but what are the odds of it actually occurring when we're observing?

Edit: Here's the paper on arXiv.
http://arxiv.org/abs/0811.3583

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Transiting Beta Pictoris b?

Post by Edasich on 9th March 2009, 6:00 am

Very intriguing.

Is Beta Pic b the transiting planet of November 1981?

In 1981, Beta Pictoris showed strong and rapid photometric variations that were attributed to the transit of a giant comet or a planet orbiting at several AUs (Lecavelier des Etangs et al. 1994, 1995, 1997; Lamers et al. 1997). Recently, a candidate planet has been identified by imagery in the circumstellar disk of Beta Pictoris (Lagrange et al. 2009). This planet, named Beta Pic b, is observed at a projected distance of 8AU from the central star. It is therefore a plausible candidate for the photometric event observed in 1981. The coincidence of the observed position of the planet in November 2003 and the calculated position assuming that the 1981 transit is due to a planet orbiting at 8 AU is intriguing. Assuming that the planet that is detected on the image is the same as the object transiting in November 1981, we estimate ranges of possible orbital distances and periods. In the favored scenario, the planet orbits at about 8 AU and was seen close to its quadrature position in the 2003 images. In this case, most of the uncertainties are related to error bars on the position in 2003. Uncertainties related to the stellar mass and orbital eccentricity are also discussed. We find a semi-major axis in the range [7.6-8.7] AU and an orbital period in the range [15.9-19.5] years. We give predictions for imaging observations at quadrature in the southwest branch of the disk in future years (2011-2015). We also estimate possible dates for the next transits and anti-transits.


According to their calculations, Beta Pictoris b's radius may span between 2.3-4 Jupiter radii. affraid
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Sirius_Alpha on 9th March 2009, 8:59 am

Very interesting indeed. It would make sense, with the disk being edge-on and all.
If indeed it's a transiting planet, it'll transit next between Sep 2013, and Dec 2020.
The paper writes that,

If future observations happen to confirm that Beta Pictoris b is a transiting planet, the planet would be extraordinary transiting planet because it is
1) A planet transiting in front of a 3.8 magnitude star. By comparison with what has been done in the case of planets transiting 7th magnitude stars (e.g. Charbonneau et al. 2002; Sing et al. 2008a, 2008b), the atmosphere of this planet could be probed with unprecedented detail for an extrasolar planet.
2) a young planet with circumplanetary material. Through detailed transit observations, this planet could give unique information on the planet environment including rings and satellites, at a stage when satellites are still forming or just formed.
3) a planet at 8 AU. This would give access to transit observations of a planet far from its parent star, a situation more like the giant planet of the solar system and different from the hot-Jupiters

Very interesting stuff.

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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Sirius_Alpha on 9th March 2009, 12:19 pm

Would someone check my math?
Assuming Beta Pictoris has a radius of 1.8 solar radii, and that Bet Pic b is indeed a transiting planet,
if it has a radius of 2 R_j, could we expect a transit depth of ~0.0126%?
if it has a radius of 4 R_j, could we expect a transit depth of ~5%?

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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Lazarus on 9th March 2009, 3:29 pm

Would be a fascinating result.

And would blast HD 80606b's record for the longest-period transiting planet completely out of the water.
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Edasich on 9th March 2009, 4:35 pm

With a radius of 4 Rj, it would look as large as a M-dwarf star.
A very very bloated jovian. cyclops
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Lazarus on 9th March 2009, 6:20 pm

I get 1.3% and 5.2% for the 2 RJ case and 4 RJ case respectively.

Well it is a young system so the planet hasn't had much time to cool and contract. However as the paper says, the planet seems too large. For example, the paper referenced at the Brown Dwarf and Extra-Solar Giant Planet Calculator (R.I.P.) seems to predict a radius around 1.4 Jupiter radii for such an object.

From the paper...
The observations are more consistent with a circumplanetary (proto-satellite) dust disk or a ring system around the planet, as recently inferred for the planet Fomalhaut b in a similar young debris disk (Kalas et al. 2008).

So worlds like Beta Pictoris b and Fomalhaut b may provide windows into the formation of satellite systems around gas giants. Like the hunt for exoplanets, the first results of the search for exomoons are the discs from which these objects form...
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Re: Possible image of an exoplanet next to Beta Pictoris

Post by Sirius_Alpha on 9th March 2009, 7:40 pm

Lazarus wrote:I get 1.3% and 5.2% for the 2 RJ case and 4 RJ case respectively.
Ah, forgot to move decimal over. Mad Lol thanks.
Do you think that if Bet Pic b transits, any hypothetical moons will be the first exomoons detected? Or do you think we might have found others by then?

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Re: Possible image of an exoplanet next to Beta Pictoris

Post by marasama on 10th March 2009, 2:01 pm

Could the dimming be cause by a moon or ring system instead of the large radius?

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