HD 179070

HD 179070
Observation data
Epoch J2000      Equinox J2000
Constellation Lyra[1]
Right ascension 19h 09m 26.8351s[2]
Declination +38° 42′ 50.455″[2]
Apparent magnitude (V) 8.25[3]
Characteristics
Spectral type F6IV[4]
Apparent magnitude (J) 7.229±0.032[5]
Apparent magnitude (H) 7.031±0.023[5]
Apparent magnitude (K) 6.945±0.018[5]
Variable type Planetary transit variable[4]
Astrometry
Proper motion (μ) RA: 27.951±0.054[2] mas/yr
Dec.: 28.585±0.056[2] mas/yr
Parallax (π)9.1859 ± 0.0323[2] mas
Distance355 ± 1 ly
(108.9 ± 0.4 pc)
Details[6]
Mass1.408+0.021
−0.030 M☉
Radius1.902+0.018
−0.012 R☉
Luminosity5.188+0.142
−0.128 L☉
Surface gravity (log g)4.026±0.004 cgs
Temperature6305±50 K
Metallicity [Fe/H]−0.03±0.10 dex
Rotation12.62±0.03 d[3]
Rotational velocity (v sin i)8.4±0.5[3] km/s
Age2.60±0.16 Gyr
Other designations
HIP 94112, Kepler-21, KOI-975, KIC 3632418, TYC 3120-963-1, 2MASS J19092683+3842505[7]
Database references
SIMBADdata

HD 179070 also known as Kepler-21 is a F-type subgiant star. A transiting exoplanet was discovered orbiting this star by the Kepler spacecraft.[4] At a magnitude of 8.25 this was the brightest star observed by Kepler to host a validated planet until the discovery of an exoplanet orbiting HD 212657 in 2018.[3][8]

Planetary system

The single known planet orbiting this star was identified as a candidate based on photometry from the first four months of data from the Kepler spacecraft.[9] Confirmation was obtained in 2012 after extensive follow-up observations and analysis of the Kepler light curves.[4]

The calculated density of the planet is approximately 6.4 g cm−3, similar to earth's 5.5 g cm−3, which suggests a rocky composition. With an equilibrium temperature of 2025 Kelvin, the top few-hundred kilometers of the planet is probably molten.[3]

The HD 179070 planetary system[3]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
Kepler-21b 5.08±1.72 M⊕ 0.0427172±0.0000003 2.7858212±0.0000032 0.02±0.1 83.20+0.28
−0.26°		 1.639+0.019
−0.015 R⊕

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Vizier query form
  2. 1 2 3 4 5 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.
  3. 1 2 3 4 5 6 López-Morales, Mercedes; et al. (2016). "Kepler-21b: A Rocky Planet Around a V = 8.25 Magnitude Star". The Astronomical Journal. 152 (6). 204. arXiv:1609.07617. Bibcode:2016AJ....152..204L. doi:10.3847/0004-6256/152/6/204.
  4. 1 2 3 4 Howell, Steve B.; et al. (2012). "Kepler-21b: A 1.6 REarth Planet Transiting the Bright Oscillating F Subgiant Star HD 179070". The Astrophysical Journal. 746 (2). 123. arXiv:1112.2165. Bibcode:2012ApJ...746..123H. doi:10.1088/0004-637X/746/2/123.
  5. 1 2 3 Skrutskie, M. F.; et al. (2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708. Vizier catalog entry
  6. ↑ Silva Aguirre, V.; et al. (2015). "Ages and fundamental properties of Kepler exoplanet host stars from asteroseismology". Monthly Notices of the Royal Astronomical Society. 452 (2): 2127–2148. arXiv:1504.07992. Bibcode:2015MNRAS.452.2127S. doi:10.1093/mnras/stv1388.
  7. ↑ "HD 179070". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-06-10.
  8. ↑ Mayo, Andrew W.; et al. (2018). "275 Candidates and 149 Validated Planets Orbiting Bright Stars in K2 Campaigns 0–10". The Astronomical Journal. 155 (3). 136. arXiv:1802.05277. Bibcode:2018AJ....155..136M. doi:10.3847/1538-3881/aaadff.
  9. ↑ Borucki, William J.; et al. (2011). "Characteristics of Planetary Candidates Observed by Kepler. II. Analysis of the First Four Months of Data". The Astrophysical Journal. 736 (1). 19. arXiv:1102.0541. Bibcode:2011ApJ...736...19B. doi:10.1088/0004-637X/736/1/19.

Coordinates: 19h 09m 26.8351s, +38° 42′ 50.455″

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