It seems that most of the exoplanets so far discovered are around F,G and K main-sequence dwarf stars, with a few exceptions. It seems that these categories are the main focus for planet hunting, so stars of types A and up are not surveyed so often.
My question is, do other star types exhibit properties that could make the radial velocity measurements unreliable (e.g. M-type dwarfs often exhibit strong flare activity), or is the bias towards FGK stars because these systems are most like Sol, and therefore in the opinion of most, the most likely to have life-bearing planets?
Candidate stars for planet hunting
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Cormoran
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Good question...
I can see why no-one would look at type O stars, as they are so rare and so short lived. It may also be that when this type of star 'turns on' the blast wave is so fierce it disperses protoplanetary nebulae very effectively.
Both O and B type stars are massive. This would make the detection of planets through analysis of proper motions more difficult. Its no surprise that many of the planets so far discovered are Epistellar Giants. The combination of thier mass and thier rapid orbits make the primary star's path deviate more noticeably than would a more 'Sol-like' system. The more mass the star has, the closer the baricenter of the Star/Planet is to the true center of the star, and therefore the less its motion deviates.
Planets of A type stars may be difficult to detect for the same reasons.
Any thoughts from the professionals out there?
Cheers,
Cormoran
I can see why no-one would look at type O stars, as they are so rare and so short lived. It may also be that when this type of star 'turns on' the blast wave is so fierce it disperses protoplanetary nebulae very effectively.
Both O and B type stars are massive. This would make the detection of planets through analysis of proper motions more difficult. Its no surprise that many of the planets so far discovered are Epistellar Giants. The combination of thier mass and thier rapid orbits make the primary star's path deviate more noticeably than would a more 'Sol-like' system. The more mass the star has, the closer the baricenter of the Star/Planet is to the true center of the star, and therefore the less its motion deviates.
Planets of A type stars may be difficult to detect for the same reasons.
Any thoughts from the professionals out there?
Cheers,
Cormoran
'...Gold planets, Platinum Planets, Soft rubber planets with lots of earthquakes....' The HitchHikers Guide to the Galaxy, Page 634784, Section 5a. Entry: Magrathea
chaos syndrome wrote:My question is, do other star types exhibit properties that could make the radial velocity measurements unreliable (e.g. M-type dwarfs often exhibit strong flare activity)?
As far as I know, you're correct. F, G, and K stars are spectroscopically the most quiet stars, and luminous enough. There are plenty of stable M dwarfs, but they're too dim and thus difficult to observe. Stars earlier than F are too unquiet, so the signal caused by the planet is lost. Probably there is also some bias towards the more life-friendly systems, as well as metal-rich stars because it seems that planets are much more common around them.