Comments on: Does the planet Fomalhaut b exist?

By: Planet Retraction?? « Dr. Erika Grundstrom

Planet Retraction?? « Dr. Erika Grundstrom — Mon, 06 Feb 2012 07:26:19 +0000

[...] Astronomer Phil Plait gives a great overview of the topic here and at the bottom of the post has a FANTASTIC little slideshow gallery detailing the planets we [...]

By: Ole

Ole — Fri, 03 Feb 2012 15:39:50 +0000

I hear that the people of Formalhaut b has issued a statement that the Earth does not exist.

By: Friday links

Friday links — Fri, 03 Feb 2012 12:12:08 +0000

[...] It turns out one of the first planets ever directly imaged – Fomalhaut B – is probably not a planet after all. The good news is, there are other confirmed direct observations of exoplanets (see the [...]

By: andy

andy — Thu, 02 Feb 2012 23:35:51 +0000

@Matt K: the orbit postulated for this object was initially calculated assuming that this is the object responsible for the eccentricity of the debris ring. If the ring-crossing orbit is correct, the mass must be far lower than the initial estimates: an upper limit of 10 Earth masses is given in the paper, so we may well be looking at a super-Earth planet or smaller. According to Kennedy & Wyatt (2011) “Collisional Evolution of Irregular Satellite Swarms: Detectable Dust around Solar System and Extrasolar Planets” it may even be possible that Fomalhaut b is a binary planet… time for the space artists I think!

By: Matt K

Matt K — Thu, 02 Feb 2012 08:17:51 +0000

The planet still hasn’t been ruled out – if you look at Figure 2 in the paper, the planet could be 1.0 Jupiter masses (with an age of 400 Myr for the planet) and still not be detected. The original 2008 paper even stated a limit of 3 Jupiter masses from dynamical arguments. (Why? If Fomalhaut b is greater then 3 Jupiter masses, its gravity would have ripped up the large dust ring seen there).

The authours have done a very nice job with the data reduction and demonstrating that they have the sensitivity for their reported results, so it is a very solid upper limit there.

Regardless, it was known from the first paper in 2008 that we’re almost certainly looking at a cloud of dust. The issue is whether the dust is in orbit about a planet (we can’t see the planet’s flux because its surface area is so small) or is it a gravitationally unbound clump of dust from a recent collision?

By: Jason Sheroan

Jason Sheroan — Thu, 02 Feb 2012 03:56:23 +0000

It’s 2012 ya know. So that can only mean that it WAS there at one time, but is now on it’s way to intercept Earth as… (cue music) FOMALHAUT X! (echo,echo,echo…)

By: apeleytheros

apeleytheros — Thu, 02 Feb 2012 01:38:48 +0000

what are the chances of the supposed planet moving faster or on a different than assumed orbit?

…..
Red Matter or Parallax, your choice

By: ND

ND — Wed, 01 Feb 2012 15:09:17 +0000

Dutch Railroader,

Nice

Probably the best scene in STOS. William Windom outdid Shatner

By: Captn Tommy

Captn Tommy — Wed, 01 Feb 2012 14:34:44 +0000

As I read this blog entry, the thought occured if we are looking a a large clump of dust/debris and it is not a planet, perhaps it is GOING to BE a PLANET.

Gravity is a strange thing, if there is a clump there is gravity. A visible clump (from 25 ly) means a lot of gravity, which means we are probably looking a preproto-planet, which is far more interesting than a planet (we have a lot of them to study).

This is something new to study, a clumping dust ball, a super dust bunny, sweeping up more dust as it travels in ond out of the accretion disk. Get a doppler on it see if it is spinning. You Astronomers may have the rarest of rare (for now) a pre-pre-planet.
I smell papers (mention me as a contributor, please)

There is no bad Astronomy in this!

Captn Tommy

By: andy

andy — Wed, 01 Feb 2012 08:16:22 +0000

As discussed in the paper, this cannot be an optically-thick disc or ring system: the relative locations of the star, Fomalhaut b and us here on Earth means it would be very difficult for Fomalhaut b to send much visible light in our direction. It essentially has to be an optically-thin dust cloud which leaves the irregular satellite swarm or planetesimal collision remnant scenarios.

The argument against the collision remnant is that this would be far more likely within the dust ring rather than outside it, so perhaps if this is the explanation we should expect to be seeing more objects like Fomalhaut b within the debris ring. Then again the issues with speckles and image noise mean that we would probably miss such objects within the dust ring.

Certainly we cannot say that Fomalhaut b represents the direct detection of a planet though… the infrared results show we are not seeing the planet itself even if one is actually there.

As for planet definitions… oh no not this again…