Still working on an the long rumoured planet candiate around a nearby white dwarf has finally been made public
Fergal Mullally (U Texas) announced that they have strong evidence for a 2+ Jupiter mass planet around the white dwarf GD66 - a pulsating moderate temperature hydrogen white dwarf that is about 50 pc away.
Detection was through timing of pulsations, over a period of few years they have significant non-monotonic timing variation consistent with a planet in a circular 4 year orbit (or somewhat period longer if eccentric) - probably have to wait for JWST for imaging confirmation, but timing will verify, or fail, the presence of a planet on a 2-3 year time scale.
Planet is bordeline Spitzer candidate, and Spitzer should look for the associated mid-infrared excess this autumn - if the orbit inclination is high enough (ie mass is higher than minimum timing mass) and if atmospheric models for mid-IR emission are good then there is a chance Spitzer will see the object, blended with the white dwarf emission.
Looks very interesting, almost there.
Comments
Please forgive my ignorance. Does "pc" stand for parsec? And if I recall a parsec is 3 light years?
Posted by: Jeff | June 27, 2007 8:41 AM
yes, pc is parsec - which is just over 3 light years
Posted by: Steinn Sigurdsson | June 27, 2007 8:52 AM
1 Parsec = approximately
1.53388225 × 10^14 furlongs.
I derive this from:
Parsec: A unit of astronomical distance equal to 3.26 light years, or 206265 AU, which equals 3.08 x 10^13 kilometers.
For background, see Wikipedia:
"The first direct measurements of an object at interstellar distances were undertaken by Friedrich Wilhelm Bessel in 1838, who used the width of the Earth's orbit as a baseline to calculate the distance of 61 Cygni using parallax and trigonometry. The parallax of a star is half of the angular distance a star appears to move relative to the celestial sphere as Earth orbits around the Sun; or, equivalently, it is the angle subtended at a star by the semi-major axis of the Earth's orbit. The use of the parsec as a unit of distance follows naturally from this method, since distance (in parsecs) is simply the reciprocal of the parallax angle (in arcseconds). That is, it is the distance at which the semi-major axis of the Earth's orbit would subtend an angle of one second of arc. (See diagram above.)"
"Though it had probably been used before, the term parsec was first mentioned in an astronomical publication in 1913, when Astronomer Royal Frank Watson Dyson expressed his concern for the need of a name for that unit of distance: he proposes the name astron, but mentions that Carl Charlier had suggested siriometer, and Herbert Hall Turner had suggested parsec...."
"... The parallax method is the fundamental calibration step for distance determination in astrophysics, and the natural unit for such measurements, the parsec, has become the most commonly used unit of distance in scholarly astronomical publications. Articles aimed at a wider audience, such as in newspapers and popular science magazines, often use a more intuitive unit, the light-year (LY)."
"There is no star whose parallax is more than 1 arcsecond. Other than the Sun, the closest star to the Earth, which therefore has the largest measured parallax, is Proxima Centauri with a parallax of 0.77233 arcseconds; it is thus 1.295 pc (4.225 LY) away from the Earth...."
Posted by: Jonathan Vos Post | June 27, 2007 9:40 AM
Hmmm. Non-ASCII chasracter. Try again:
1 Parsec = approximately
1.53388225 x 10^14 furlongs.
1 Parsec = 1.21483474 x 10^18 inches.
1 Parsec = 3.08568025 x 10^26 angstroms.
Now, how about civilizations on moons orbiting Jovian planets circling white dwarfs...
Posted by: Jonathan Vos Post | June 27, 2007 9:44 AM
Parsec sounds cooler ;)
Now THAT is an interesting subject.
Posted by: Jeff | June 27, 2007 10:02 AM
Now this is not just another interesting find but perhaps the one step before we have a more bizarre one i.e. a planet around a stellar mass black hole. Since we have now found planets around main sequence stars, brown dwarfs, pulsars, white dwarfs why not a black hole then?
Posted by: Shaun | June 28, 2007 11:15 AM
Planets around black holes are trickier unless they follow a formation pathway similar to pulsars, i.e. they are formed in some sort of fall back disk after a supernova. Though, I guess you could get one captured by a supermassive black hole...
Posted by: JohnD | June 28, 2007 1:35 PM
the hardest part about finding planets around black holes is what the signal is
- I know two - seeing tidal disruption of a planet hitting a low mass black hole, which requires a lot of luck; or seeing gravitational radiation from a planet around a low mass supermassive black hole - which requires new instruments, like LISA, the Milky Way and a lot of luck
a core collapse black hole might retain any planets that formed around its progenitor, which is conceivable, but not known - O star surrounding are a bit hostile, might be too much for planet formation
black holes in dense stellar systems like globular clusters or centers of galaxies could capture planets if they are there to be captured
be fun to do, but hard to verify
Posted by: Steinn Sigurdsson | June 29, 2007 2:39 AM
I am mistaken...
Scott Gaudi just reminded me that microlensing can detect planets orbiting isolated black holes, if they happen to be caught as lenses
Odds are not bad (one of the old microlensing events is probably a black hole), although you need a good alignment to see any planets, and of course they have to be there in the first place
Posted by: Steinn Sigurdsson | June 29, 2007 5:37 AM
Microlensing...hmmm interesting.
Maybe I'm just being too overly optimistic maybe even unrealistic but somehow I just have this thinking that if we can find planets orbiting pulsars even if they happened to be formed from the debris arising out of hypernovaes or supernovaes and not original planets like the Earth is, a similar pehnomenon could also conceivably germinate planets around black holes, no?
And then there is B1620-26c, given the compact nature of GCs, capture events are probably a higher probability than in the rest of the galaxy, so if it can happen in the B1620-26 system why not also a black hole stealing some planets from some unlucky lesser stars?
Posted by: Shaun | June 29, 2007 8:48 AM