<p>The answer to this, and other questions of its kind about exoplanets, can easily be found at the website <a href="http://exoplanets.org/" rel="nofollow noreferrer">http://exoplanets.org/</a>  This site contains a very authoritative catalogue of exoplanet discoveries and has tools to enable tables and plots of many variables to be constructed.</p>

<p>For example, to handle your question, I produced the following plot for exoplanets <em>discovered using the doppler radial velocity technique</em>. 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 <a href="http://adsabs.harvard.edu/abs/2013arXiv1310.1994B" rel="nofollow noreferrer">Borginiet et al. (2013)</a>. 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.</p>

<p>It is difficult to find exoplanets around high-mass <em>main sequence</em> 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 <em>would have been</em> 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 <em>was</em> an early-type A star on the main sequence.</p>

<p><img src="https://i.sstatic.net/ZTYyv.png" alt="Host temperature vs planet mass"></p>

CC BY-SA 3.0
2014-12-28T04:51:29.353Z
how do you select the x-axis range? I tried your way, but found the x-axis could be larger than 7000.
questionhang
CC BY-SA 3.0
2014-12-27T11:33:27.270Z
2014-12-27T11:33:27.270Z
ProfRob
<p><a href="http://exoplanet.eu/catalog/hd_103774_b/" rel="nofollow">HD 103774 b</a>, detected by radial velocity, orbits a star of spectral type F5V according to <a href="http://exoplanet.eu/catalog/all_fields/?f=%22radial%22%20IN%20detection%20OR%20%22astrometry%22%20IN%20detection" rel="nofollow">The Extrasolar Planet Encyclopeadia</a>.</p>

<p><a href="http://exoplanet.eu/catalog/hd_102956_b/" rel="nofollow">HD 102956 b</a>, detected by radial velocity, <a href="http://iopscience.iop.org/2041-8205/721/2/L153/pdf/2041-8205_721_2_L153.pdf" rel="nofollow">orbits a spectral type A subgiant</a>, the star of the "earliest" type harboring a planet detected by radial velocity, I could find (as of May 2014).</p>

<p>The entry for
<a href="http://exoplanet.eu/catalog/kepler-88_c/" rel="nofollow">Kepler-88 c</a> around a spectral type B star (according to the catalog as of May 2014) appears to be incorrect, or encodes something else, <a href="http://arxiv.org/pdf/1311.4335v2.pdf" rel="nofollow">the star should be classified as spectral type G6V</a>.</p>

CC BY-SA 3.0
2014-05-16T00:46:21.283Z
About Kepler-88, also the star is 1 solar mass.
Py-ser
CC BY-SA 3.0
2014-05-18T08:40:30.610Z
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
CC BY-SA 3.0
2014-12-27T11:26:49.620Z
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.
ProfRob
CC BY-SA 3.0
2014-05-15T22:18:03.963Z
2014-05-15T22:18:03.963Z
Gerald
<p>We have discovered planets in  Beta_Pictoris(A6V)<a href="http://en.wikipedia.org/wiki/Beta_Pictoris_b" rel="nofollow">here</a> and Fomalhaut alpha(A3v)<a href="http://en.wikipedia.org/wiki/Fomalhaut" rel="nofollow">here</a>. <br/>
However they were discovered by direct images.<br/></p>

<p>There should be an stellar type limit by RV? <br/> 
What is the most early type ever found?<br/></p>

CC BY-SA 3.0
2014-05-15T05:59:18.267Z
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
CC BY-SA 3.0
2014-05-15T08:07:36.267Z
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
CC BY-SA 3.0
2014-05-15T08:17:45.733Z
'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
CC BY-SA 3.0
2014-05-15T13:00:02.710Z
It is not "too general". We have only found no more than 2k EXOPLANETS.
questionhang
CC BY-SA 3.0
2014-05-15T14:42:20.880Z
direct imaging is one of the methods of discovering exoplanets. you can take a look at http://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets
questionhang
CC BY-SA 3.0
2014-05-16T00:48:52.453Z
I didn't know about the "direct image" terminology. Then you could add a link. About the "too general" issue, you didn't catch my point. You want to know what is the earliest stellar type hosting a planet inferred by radial velocity, right?
Py-ser
CC BY-SA 3.0
2014-05-16T01:33:18.833Z
yes. generally it is difficult to discover a early type star hosting a planet because early type stars are more massive and have less absorption lines.
questionhang
<planet>
Which is the most early type star with a planet discovered by radial velocity method?
questionhang
# Which is the most early type star with a planet discovered by radial velocity method?

(Asked by: username_0 on 2014-05-15)

We have discovered planets in Beta\_Pictoris(A6V)[here](http://en.wikipedia.org/wiki/Beta_Pictoris_b) and Fomalhaut alpha(A3v)[here](http://en.wikipedia.org/wiki/Fomalhaut).   
However they were discovered by direct images.

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

**Tags:** planet

> **Comments:**
> **username_1**: What do you mean by "direct images"? Eclipses?  And what do you mean by "most early type ever found"? If we observed O0 stars?  
> **username_0**: 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.  
> **username_1**: '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".  
> **username_0**: It is not "too general". We have only found no more than 2k EXOPLANETS.  
> **username_0**: direct imaging is one of the methods of discovering exoplanets. you can take a look at http://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets  
> **username_1**: I didn't know about the "direct image" terminology. Then you could add a link. About the "too general" issue, you didn't catch my point. You want to know what is the earliest stellar type hosting a planet inferred by radial velocity, right?  
> **username_0**: yes. generally it is difficult to discover a early type star hosting a planet because early type stars are more massive and have less absorption lines.  

---

## 2 answers

### Answer by username_2 on 2014-12-27. Score: 1 | Accepted answer

The answer to this, and other questions of its kind about exoplanets, can easily be found at the website <http://exoplanets.org/> 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)](http://adsabs.harvard.edu/abs/2013arXiv1310.1994B). 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](https://i.sstatic.net/ZTYyv.png)

> **Comments:**
> **username_0**: how do you select the x-axis range? I tried your way, but found the x-axis could be larger than 7000.  

---

### Answer by username_3 on 2014-05-15. Score: 2

[HD 103774 b](http://exoplanet.eu/catalog/hd_103774_b/), detected by radial velocity, orbits a star of spectral type F5V according to [The Extrasolar Planet Encyclopeadia](http://exoplanet.eu/catalog/all_fields/?f=%22radial%22%20IN%20detection%20OR%20%22astrometry%22%20IN%20detection).

[HD 102956 b](http://exoplanet.eu/catalog/hd_102956_b/), detected by radial velocity, [orbits a spectral type A subgiant](http://iopscience.iop.org/2041-8205/721/2/L153/pdf/2041-8205_721_2_L153.pdf), 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](http://exoplanet.eu/catalog/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](http://arxiv.org/pdf/1311.4335v2.pdf).

> **Comments:**
> **username_1**: About Kepler-88, also the star is 1 solar mass.  
> **username_0**: 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.  
> **username_2**: 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.  

---

