HD 99109

HD 99109 is an orange-hued star with an exoplanetary companion in the constellation of Leo. It has an absolute visual magnitude of +9.10,[2] which is too faint to be visible to the naked eye. The distance to this system is 179 light-years based on parallax, and it is drifting further away with a radial velocity of +33 km/s.[1] The star is one and half degrees away from the celestial equator to the south.

HD 99109 / Shama
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Leo
Right ascension 11h 24m 17.3586s[1]
Declination –01° 31′ 44.6635″[1]
Apparent magnitude (V) +9.10[2]
Characteristics
Spectral type G8/K0IV[3]
B−V color index 0.874±0.002[2]
Astrometry
Radial velocity (Rv)+33.34±0.28[1] km/s
Proper motion (μ) RA: –178.777[1] mas/yr
Dec.: –159.754[1] mas/yr
Parallax (π)18.2228 ± 0.0551 mas[1]
Distance179.0 ± 0.5 ly
(54.9 ± 0.2 pc)
Absolute magnitude (MV)5.62[2]
Details
Mass0.93±0.02[4] M☉
Radius0.90±0.03[4] R☉
Luminosity0.56±0.02[4] L☉
Surface gravity (log g)4.49±0.03[4] cgs
Temperature5,270±24[4] K
Metallicity [Fe/H]0.315±0.030[5] dex
Rotational velocity (v sin i)1.86±0.50[5] km/s
Age6±3 Gyr[4]
≥ 12.2[6] Gyr
Other designations
Shama, BD–00°2437, HD 99109, HIP 55664, SAO 138182
Database references
SIMBADdata
Extrasolar Planets
Encyclopaedia		data

The stellar classification of this star is G8/K0IV,[3] matching a late G or early K-type subgiant star. It appears to be past the end of its main sequence lifetime, having exhausted the supply of hydrogen at its core.[6] The star is 93% as massive as the Sun and has 90% of the Sun's radius.[4] It is spinning with a projected rotational velocity of ~2 km/s[5] and has over twice the abundance of iron relative to hydrogen than the Sun. The star is radiating 56% of the Sun's luminosity from its photosphere at an effective temperature of 5,270 K.[4] As of 2006, one extrasolar planet has been confirmed to be orbiting the star.[5]

The star HD 99109 is named Shama. The name was selected in the NameExoWorlds campaign by Pakistan, during the 100th anniversary of the IAU. Shama is an Urdu literary term meaning a small lamp or flame.[7][8]

Planetary system

The planet HD 99109 b has an orbit comparable in eccentricity to the planet Mars in the Solar System but has a mass at least half that of Jupiter. Stability analysis reveals that Earth-size planets could have stable orbits in the planet's Trojan points, located 60 degrees ahead and behind the planet's position in its orbit.[6]

The HD 99109 planetary system[5]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b / Perwana >0.502 ± 0.070 MJ 1.105 ± 0.065 439.3 ± 5.6 0.09 ± 0.16 — —

See also

References
  1. 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.
  2. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
  3. Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  4. Bonfanti, A.; Ortolani, S.; Nascimbeni, V. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: 14. arXiv:1511.01744. Bibcode:2016A&A...585A...5B. doi:10.1051/0004-6361/201527297. S2CID 53971692. A5.
  5. Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701. S2CID 119067572.
  6. Schwarz, R.; et al. (November 2007). "Survey of the stability region of hypothetical habitable Trojan planets". Astronomy & Astrophysics. 474 (3): 1023–1029. Bibcode:2007A&A...474.1023S. doi:10.1051/0004-6361:20077994.: HD 93083, HD 17051, HD 28185, HD 27442, HD 188015, HD 99109, HD 221287
  7. "Approved names". NameExoworlds. IAU. Retrieved 2020-01-02.
  8. "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
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