Ten new debris disks

New Debris Disks around:
Gliese 581, HD 40979, HD 43162, HD 46375, HD 50499, HD 73526, HD 137759, HD 178911, HD 187085, HD 202206, HD 216435

On the Relationship Between Debris Disks and Planets
http://arxiv.org/abs/0907.0028

abstract wrote:

Dust in debris disks is generated by collisions among planetesimals. The existence of these planetesimals is a consequence of the planet formation process, but the relationship between debris disks and planets has not been clearly established. Here we analyze Spitzer/MIPS 24 and 70 micrometer data for 150 planet-bearing stars, and compare the incidence of debris disks around these stars with a sample of 118 stars around which planets have been searched for, but not found. Together they comprise the largest sample ever assembled to deal with this question. The use of survival analysis techniques allows us to account for the large number of non-detections at 70 micrometer. We discovered 10 new debris disks around stars with planets and one around a star without known planets. We found that the incidence of debris disks is marginally higher among stars with planets, than among those without, and that the brightness of the average debris disk is not significantly different in the two samples. We conclude that the presence of a planet that has been detected via current radial velocity techniques is not a good predictor of the presence of a debris disk detected at infrared wavelengths.

It doesn't seem to give the semi-major axes of the new debris disks, but it does give their brightness. Is there any way to determine their semi-major axes from the data given in the paper?

So the 581 has a disc, but the 876 (which clearly was doing something unusual to produce two massive planets in such close orbits around an M dwarf) does not...

The plot thickens...

Hmm. Regarding the closeness of the gas planets at Gliese 876, the protoplanetary disk was obviously much more massive than Gliese 581's, and this probably helped to facilitate migration. Unless the disks were initially the same, but somehow Gliese 581 absorbed most of its circumstellar material.

Gliese 581 planetary system total mass -> 30 Earth-masses
Gliese 876 planetary system total mass -> 1,000 Earth-masses.

Not a whole lot of difference between these two stars, other than that Gliese 581 is less metallic. (Gliese 876 [Fe/H] = -0.12, Gliese 581 [Fe/H] = -0.33). Gliese 317, with a metallicity of [Fe/H] = -0.23, has one, and likely a second gas planet.

I keep thinking that all of the anomalies at Gliese 876 can be explained by a massive disk early in its history. But the apparent absense of such a disk today is a problem. (by the way, here's the paper on that). Is it possible that the disk existed, but was later removed?

`Debris are a big hindrance for any future plans.!

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katzky wrote:

`Debris are a big hindrance for any future plans.!

Debris disks, like those of our solar system, are probably easily traversible by spacecraft without a problem, assuming it isn't too dense. With as old as Gliese 581, I would expect the debris disk to be rather tenuous.

I wonder if it would be possible to constrain the inclination of the disk? Would be interesting (though sort of unsurprising) if it is in agreement with dynamical constraints for the inclination of the system.

Do they know at which distance of Gl581 is the discovered disc of dusts?

As far as I know, this is the first and only time any such disk has been reported for many of these. No where is it reported the distance the disk is from the stars. I sure wish I knew though =s. Maybe there's something one can do with the luminosity of the disks, which it does give, and the disk mass (I don't recall if it gives this or not) and assuming a certain particle size (which I don't recall if they give).