HD 102956 b

HD 102956 b or Isagel is an extrasolar planet discovered in 2010 by a team of American astronomers led by John Johnson using Doppler spectroscopy and the Keck Observatory in Hawaii. HD 102956 b is in the orbit of host star HD 102956. The planet is at most the mass of Jupiter, orbiting every 6.5 days at a distance of 12 million km. HD 202956 b has a very circular orbit.[1] The system is roughly 399 light years from us.

HD 102956 b

Artist's impression HD 102956 b
Discovery[1]
Discovered by	Johnson et al.
Discovery site	Keck Observatory
Discovery date	2010
Detection method	Doppler spectroscopy
Orbital characteristics[2]
Semi-major axis	0.0807±0.0073 AU
Eccentricity	0.037±0.019
Orbital period	6.49470±0.00019 d
Time of perihelion	2455351.45±0.64 JD
Argument of perihelion	301±33 º
Semi-amplitude	74.6±1.8 m/s
Star	HD 102956
Physical characteristics[2]
Mass	≥0.960±0.023 MJ

HD 102956

Observation data Epoch J2000      Equinox J2000
Constellation	Ursa Major
Right ascension	11^h 51^m 22.5111^s[3]
Declination	+57° 38′ 26.6427″[3]
Characteristics
Evolutionary stage	Main sequence
Spectral type	A
Astrometry
Radial velocity (Rv)	−25±83 km/s
Proper motion (μ)	RA: −11.24±0.049[3] mas/yr Dec.: −17.578±0.049[3] mas/yr
Parallax (π)	8.1753 ± 0.0290[3] mas
Distance	399 ± 1 ly (122.3 ± 0.4 pc)
Absolute magnitude (MV)	2.5
Details
Mass	1.68±0.11 M☉
Radius	4.4±0.1 R☉
Luminosity (visual, LV)	11.6±0.5 L☉
Temperature	5054±44 K
Metallicity [Fe/H]	+0.19±0.04 dex
Rotational velocity (v sin i)	0.30 km/s
Other designations
BD+58 1340, HIP 57820, SAO 28161, TYC 3839-00846-1, 2MASS J11512253+5738267[4]
Database references
SIMBAD	data
Exoplanet Archive	data

Discovery and nomenclature

HD 102956 is located inside the Big Dipper.

The name HD 102956 derives directly from the fact that the star is the 102,956th star catalogued in the Henry Draper catalog. The designation of b is given to the first planet orbiting a given star.

The star is one of the 2.5 million brightest stars in the sky and is part of the Tycho-2 Catalogue. It is not visible to the naked eye with an apparent magnitude of 8.

NameExoWorlds

In 2019 this planet was announced as part of the IAU NameExoWorlds project[5] where it was designated as the planet that will be named by Sweden. The winning proposal was Isagel, from Nobel laureate Harry Martinson's space poem Aniara.[6]

Characteristics Host Star

HD 102956 (Aniara) is an orange subgiant with a mass and radius of 1.68 and 4.4 solar, respectively. The surface temperature is about 5054 Kelvin. The luminosity of the star exceeds that of the sun by 11.6 times. The star's age is estimated at about 2.3 billion years.

Habitability and possibility of life

Since HD 102956 b is a hot Jupiter it is unlikely that it harbors life.

References

1. Johnson, John Asher; et al. (2010). "A Hot Jupiter Orbiting the 1.7 M☉ Subgiant HD 102956". The Astrophysical Journal Letters. 721 (2): L153–L157. arXiv:1007.4555. Bibcode:2010ApJ...721L.153J. doi:10.1088/2041-8205/721/2/L153.
2. Luhn, Jacob K.; et al. (2019). "Retired A Stars and Their Companions. VIII. 15 New Planetary Signals around Subgiants and Transit Parameters for California Planet Search Planets with Subgiant Hosts". The Astronomical Journal. 157 (4). 149. arXiv:1811.03043. Bibcode:2019AJ....157..149L. doi:10.3847/1538-3881/aaf5d0.
3. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
4. "HD 102956". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-21.
5. "Name an exoplanet (press release)". 2019-06-06. Retrieved 2019-06-13.
6. https://fof.se/artikel/rymddikt-gav-namn-sveriges-exoplanet (in Swedish)

Coordinates: 11^h 51^m 23.0^s, +57° 38′ 27″