Template:Use dmy dates

Extrasolar planet List of extrasolar planets
Size comparison of HAT-P-11b (gray) with Neptune.
Parent star

<tr> <td colspan="2">Star</td> <td>HAT-P-11</td></tr><tr> <td colspan="2">Constellation</td> <td>Cygnus</td></tr><tr> <td>Right ascension</td> <td style="text-align: center">(α)</td> <td>19h 50m 50.25s[1]</td></tr><tr> <td>Declination</td> <td style="text-align: center">(δ)</td> <td>+48° 04′ 51.1″[1]</td></tr><tr> <td>Apparent magnitude</td> <td style="text-align: center">(mV)</td> <td>9.59[2]</td></tr><tr><td colspan="2">Distance</td><td>122 ± 4[1] ly
(37 ± 1[1] pc)</td></tr><tr><td colspan="2">Spectral type</td> <td>K4[2]</td></tr>

Orbital elements

<tr><td>Semimajor axis</td><td style="text-align: center">(a)</td> <td>0.053+0.0002
AU</td></tr><tr> <td>Periastron</td> <td style="text-align: center">(q)</td> <td>0.043 AU</td></tr><tr> <td>Apastron</td> <td style="text-align: center">(Q)</td> <td>0.063 AU</td></tr><tr> <td>Eccentricity</td> <td style="text-align: center">(e)</td> <td>0.198 ± 0.046</td></tr><tr><td>Orbital period</td><td style="text-align: center">(P)</td> <td>4.8878045±0.0000043[3] d
(0.013381878 ± 0.000000019 y)</td></tr><tr> <td>Orbital speed</td> <td style="text-align: center">(υ)</td> <td>118 km/s</td></tr><tr> <td>Inclination</td> <td style="text-align: center">(i)</td> <td>88.5 ± 0.6°</td></tr><tr> <td>Argument of
</td> <td style="text-align: center">(ω)</td> <td>355.2 ± 17.3°</td></tr><tr> <td>Time of transit</td> <td style="text-align: center">(Tt)</td> <td>2454605.89132 ± 0.00032 JD</td></tr>

Physical characteristics

<tr><td>Mass</td><td style="text-align: center">(m)</td><td>0.081 ± 0.009 MJ
(26 ± 3 M)</td></tr><tr><td>Radius</td><td style="text-align: center">(r)</td><td>0.422 ± 0.014 Template:Jupiter radius
(4.58 ± 0.15 Template:Earth radius)</td></tr><tr><td>Density</td><td style="text-align: center">(ρ)</td><td>1440 kg m-3</td></tr><tr><td>Surface gravity</td><td style="text-align: center">(g)</td><td>1.20 g</td></tr>

Discovery information

<tr> <td colspan="2">Discovery date</td> <td>2 January 2009</td></tr><tr> <td colspan="2">Discoverer(s)</td> <td>Bakos et al.</td></tr><tr> <td colspan="2">Discovery method</td> <td>Transit (HATNet)</td></tr><tr> <td colspan="2">Other detection methods</td> <td>Radial velocity</td></tr><tr> <td colspan="2">Discovery site</td> <td>Cambridge, Massachusetts</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>

HAT-P-11b (or Kepler-3b) is an extrasolar planet orbiting the star HAT-P-11. This planet was discovered by the transit method and submitted for publication on 2 January 2009.

This planet is located approximately 122 light-years (37 pc) away[1] in the constellation of Cygnus, orbiting the 10th magnitude K-type star HAT-P-11. This planet was the smallest transiting planet known when first discovered, with a radius about 5 times that of Earth; but is more massive than Gliese 436 b at a true mass of 26 times that of Earth. This planet orbits about the same distance from the star as 51 Pegasi b is from 51 Pegasi, typical of transiting planets. However, the orbit of this planet is eccentric, at around 0.198, unusually high for hot Neptunes. HAT-P-11b's orbit is also highly inclined, with a tilt of approximately 103 degrees relative to its star's rotation.[4][5]

The HAT-P-11 system was within the field of view of the Kepler spacecraft.[2]

Its radial velocity is drifting and this may be a result of an as-yet-undiscovered planet in the system.[2]

The planet fits models for 90% heavy elementsTemplate:Huh. Expected temperature is 878 ± 15K.[2] Actual temperature must await calculations of secondary transit.

On 24 September 2014, NASA reported that HAT-P-11b is the first Neptune-sized exoplanet known to have a relatively cloud-free atmosphere and, as well, the first time molecules, namely water vapor, of any kind have been found on such a relatively small exoplanet.[6]

See alsoEdit


  1. 1.0 1.1 1.2 1.3 1.4 (2007). Validation of the new Hipparcos reduction. Astronomy and Astrophysics 474 (2): 653–664. Vizier catalog entry
  2. 2.0 2.1 2.2 2.3 2.4 (2010). HAT-P-11b: A Super-Neptune Planet Transiting a Bright K Star in the Kepler Field. The Astrophysical Journal 710 (2): 1724–1745.
  3. (2009). Follow-up Observations of the Neptune Mass Transiting Extrasolar Planet HAT-P-11b. The Astrophysical Journal 699: L48–L51.
  4. Inclined Orbits Prevail in Exoplanetary Systems (12 January 2011).
  5. Roberto Sanchis-Ojeda, Josh N. Winn, Daniel C. Fabrycky (2012). Starspots and spin-orbit alignment for Kepler cool host stars.
  6. Clavin, Whitney (24 September 2014). NASA Telescopes Find Clear Skies and Water Vapor on Exoplanet. NASA. Retrieved 24 September 2014.

External linksEdit


Coordinates: Sky map 19h 50m 50.2469s, +48° 04′ 51.085″

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