Extragalactic planets

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Extragalactic planets

Post by NuclearVacuum on 21st July 2008, 12:23 pm

I am curious, could it be possible to look at a star in another galaxy, and see another planet. Take the Andromeda Galaxy for example, stars have been cataloged in this galaxy. Could we pick a sun-like star, search it with Doppler and transit, and could we find a planet?
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Re: Extragalactic planets

Post by Sirius_Alpha on 21st July 2008, 2:45 pm

The issue there is that the stars in Andromeda are very faint. Here is a paper from 2005 detailing the first determination of the orbits of a binary star system in the Andromeda Galaxy.

First Determination of the Distance and Fundamental Properties of an Eclipsing Binary in The Andromeda Galaxy
http://arxiv.org/abs/astro-ph/0511045

abstract wrote:We present the first detailed spectroscopic and photometric analysis of an eclipsing binary in the Andromeda Galaxy (M31). This is a 19.3-mag semi-detached system with components of late-O and early-B spectral types. From the light and radial velocity curves we have carried out an accurate determination of the masses and radii of the components. Their effective temperatures have been estimated from the modeling of the absorption line spectra. The analysis yields an essentially complete picture of the properties of the system, and hence an accurate distance determination to M31. The result is d=772+/-44 kpc ((m-M)_0=24.44+/-0.12 mag). The study of additional systems, currently in progress, should reduce the uncertainty in the M31 distance to better than 5%.


So as you can see, radial velocity measurements of extragalactic stars has only now gotten us to the ability to measure the orbital parameters of stars. And as the paper wrote, those stars are "late-O, early-B" stars, unsuitable for radial velocity detections of planets. F, G, and K stars would be several magnitudes dimmer, far beneath the ability for radial velocity measurements from Earth to get enough a high enough S/N ratio to detect anything planetary.

So the short answer to your question is "no".

Anyway, a similar feat was accomplished in 2006, with M33.
http://arxiv.org/abs/astro-ph/0606279

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Re: Extragalactic planets

Post by NuclearVacuum on 21st July 2008, 3:22 pm

Darn, but that doesn't leave out future detections from Kepler or something of that nature?
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Re: Extragalactic planets

Post by Sirius_Alpha on 21st July 2008, 5:43 pm

I think Kepler might be able to detect extragalactic planets in some of the closer dwarf galaxies if it tried. But confirmation would be difficult, if not impossible. Think about the SWEEPS planets, only two are confirmed, the rest are orbiting stars too dim to confirm their nature. So yeah, I'm sure Kepler could probably find extragalactic planets, but their masses would be vastly unconstrained.

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Re: Extragalactic planets

Post by NuclearVacuum on 21st July 2008, 6:51 pm

Hm... disappointing. But still very, very interesting.
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Re: Extragalactic planets

Post by Lazarus on 9th August 2008, 5:18 pm

arXiv:Searching for extragalactic planets
Basically, use microlensing.

Would be very interesting to find planets in different galaxy types...
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Re: Extragalactic planets

Post by Edasich on 10th September 2008, 7:42 am

http://solar-flux.forumandco.com/extrasolar-news-and-discoveries-f2/unconfirmed-unpublished-planets-catalogue-t15.htm

Here at "Take 7" is a paper about microlensing events in M31 and putative brown dwarf candidates hosts. No further explanation though...
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Re: Extragalactic planets

Post by Lazarus on 10th September 2008, 7:58 am

Maybe this should be in Detection Methods?
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Re: Extragalactic planets

Post by Sirius_Alpha on 10th September 2008, 6:12 pm

Lazarus wrote:Maybe this should be in Detection Methods?
Moved.

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Re: Extragalactic planets

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