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We have discovered planets in Beta_Pictoris(A6V)here and Fomalhaut alpha(A3v)here.
However they were discovered by direct images.

There should be an stellar type limit by RV?
What is the most early type ever found?

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What do you mean by "direct images"? Eclipses? And what do you mean by "most early type ever found"? If we observed O0 stars? – Py-ser May 15 '14 at 5:59
direct image means we see the planet directly. You can see two images at those two links above. early type, I mean ,stellar classification. It is not easy to find early type star host by a exo-planet via radial velocity. – questionhang May 15 '14 at 8:07
'What is the most early type ever found" is too general. Please, edit the question. Also about the first point, you should say something like "they were directly observable". – Py-ser May 15 '14 at 8:17
It is not "too general". We have only found no more than 2k EXOPLANETS. – questionhang May 15 '14 at 13:00
direct imaging is one of the methods of discovering exoplanets. you can take a look at – questionhang May 15 '14 at 14:42

2 Answers 2

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The answer to this, and other questions of its kind about exoplanets, can easily be found at the website This site contains a very authoritative catalogue of exoplanet discoveries and has tools to enable tables and plots of many variables to be constructed.

For example, to handle your question, I produced the following plot for exoplanets discovered using the doppler radial velocity technique. This shows effective temperature of the parent star on the x-axis, versus projected exoplanet mass $M\sin i$. The the hottest star with an RV-identified exoplanet (on the website, you can click on the points) is HD113337, an F6V-type star discovered by Borginiet et al. (2013). The next hottest is HD103774, which is given a slightly earlier spectral type of F5V. These two are joint hottest within their uncertainties. Just a touch cooler is Tau Boo.

It is difficult to find exoplanets around high-mass main sequence stars using the doppler method because of the paucity of strong, narrow spectral lines. Most of what we know is from observations of subgiant stars - i.e. stars that would have been early-type stars on the main sequence, but which have cooler photospheres after they have left the main sequence. HD102956, mentioned in another answer, is an example if this - i.e. it was an early-type A star on the main sequence.

Host temperature vs planet mass

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how do you select the x-axis range? I tried your way, but found the x-axis could be larger than 7000. – questionhang Dec 28 '14 at 4:51

HD 103774 b, detected by radial velocity, orbits a star of spectral type F5V according to The Extrasolar Planet Encyclopeadia.

HD 102956 b, detected by radial velocity, orbits a spectral type A subgiant, the star of the "earliest" type harboring a planet detected by radial velocity, I could find (as of May 2014).

The entry for Kepler-88 c around a spectral type B star (according to the catalog as of May 2014) appears to be incorrect, or encodes something else, the star should be classified as spectral type G6V.

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About Kepler-88, also the star is 1 solar mass. – Py-ser May 16 '14 at 0:46
sigh, the discovery paper(Johnson et al, 2010) of HD102956B did not mention any spectral thing. There is no spectrum or spectral line at all. – questionhang May 18 '14 at 8:40
HD 102956b (note the small letter) was discovered by the RV method, but it is a subgiant with a temperature of about 5000K. It was an early-type main sequence star. Kepler 88 was of course not discovered by the RV method (as the name suggests) and is cooler than the Sun. – Rob Jeffries Dec 27 '14 at 11:26

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