Extrasolar planet List of extrasolar planets
Size comparison of XO-4b with Jupiter.
Parent star

<tr> <td colspan="2">Star</td> <td>XO-4</td></tr><tr> <td colspan="2">Constellation</td> <td>Lynx[1]</td></tr><tr> <td>Right ascension</td> <td style="text-align: center">(α)</td> <td>07h 21m 33.159s[2]</td></tr><tr> <td>Declination</td> <td style="text-align: center">(δ)</td> <td>+58° 16′ 04.98″[2]</td></tr><tr> <td>Apparent magnitude</td> <td style="text-align: center">(mV)</td> <td>10.674 ± 0.019[3]</td></tr><tr><td colspan="2">Distance</td><td>956 ± 62[3] ly
(293 ± 19[3] pc)</td></tr><tr><td colspan="2">Spectral type</td> <td>F5V[3]</td></tr>

Orbital elements

<tr><td>Semimajor axis</td><td style="text-align: center">(a)</td> <td>0.0555 ± 0.00011 AU</td></tr><tr> <td>Periastron</td> <td style="text-align: center">(q)</td> <td>0.0554 AU</td></tr><tr> <td>Apastron</td> <td style="text-align: center">(Q)</td> <td>0.0556 AU</td></tr><tr> <td>Eccentricity</td> <td style="text-align: center">(e)</td> <td>0.0024</td></tr><tr><td>Orbital period</td><td style="text-align: center">(P)</td> <td>4.12502 ± 2e-5 d
(0.011293 y)</td></tr><tr> <td>Inclination</td> <td style="text-align: center">(i)</td> <td>88.7 ± 1.1°</td></tr><tr> <td>Time of transit</td> <td style="text-align: center">(Tt)</td> <td>2454485.9322 ± 0.0004 JD</td></tr>

Physical characteristics

<tr><td>Mass</td><td style="text-align: center">(m)</td><td>1.72 ± 0.2 MJ</td></tr><tr><td>Radius</td><td style="text-align: center">(r)</td><td>1.34 ± 0.048 Template:Jupiter radius</td></tr><tr><td>Density</td><td style="text-align: center">(ρ)</td><td>948 kg m-3</td></tr><tr><td>Surface gravity</td><td style="text-align: center">(g)</td><td>24.8 m/s²</td></tr><tr> <td>Temperature</td> <td style="text-align: center">(T)</td> <td>~1333 K</td></tr>

Discovery information

<tr> <td colspan="2">Discovery date</td> <td>May 19, 2008</td></tr><tr> <td colspan="2">Discoverer(s)</td> <td>McCullough et al.</td></tr><tr> <td colspan="2">Discovery method</td> <td>Transit</td></tr><tr> <td colspan="2">Other detection methods</td> <td>Radial velocity</td></tr><tr> <td colspan="2">Discovery site</td> <td>Maui, Hawaii</td></tr><tr> <td colspan="2">Discovery status</td> <td>Published</td></tr> <tr style="background-color: #A0B0FF;"><td align=center colspan=3>Database references</td></tr><tr valign=baseline><td colspan=2>Extrasolar Planets
</td><td>data</td></tr><tr><td colspan=2>SIMBAD</td><td>data</td></tr>

XO-4b is an extrasolar planet approximately 956 light years away in the constellation of Lynx. This planet was found by the transit method by McCullough in May 2008. The planet has mass 1.72 MJ and radius 1.34 RJ. This planet orbits very close to the F-type parent star, as it is typical for transiting planets, classing this planet as Hot Jupiter.

It takes only 4.125 days (or 99 hours) to orbit at a distance of 8.3 gigameters (0.0555 AU) away from the star.[3]

See alsoEdit


  1. (1987). Identification of a Constellation From a Position. Publications of the Astronomical Society of the Pacific 99 (617): 695–699. Vizier query form
  2. 2.0 2.1 Hog et al. (2000). Tyc 3793-1994-1. The Tycho-2 Catalogue. Retrieved 2012-02-25.
  3. 3.0 3.1 3.2 3.3 3.4 (2008). XO-4b: An Extrasolar Planet Transiting an F5V Star.

External linksEdit


  • XO-4. Exoplanets. Retrieved 2008-08-06.

Coordinates: Sky map 07h 21m 33.1657s, +58° 16′ 05.005″

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