HD 27894

HD 27894 is a 9th magnitude star located approximately 143 light years away in the constellation of Reticulum. It is an orange dwarf (spectral type K2V), a type dimmer and cooler than our Sun.

HD 27894
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Reticulum
Right ascension 04h 20m 47.0464s[1]
Declination −59° 24′ 39.0231″[1]
Apparent magnitude (V) 9.42
Characteristics
Spectral type K2 V[2]
U−B color index +0.90[3]
B−V color index +1.005[3]
Astrometry
Proper motion (μ) RA: 182.313±0.053[1] mas/yr
Dec.: 269.911±0.085[1] mas/yr
Parallax (π)22.7910 ± 0.0306[1] mas
Distance143.1 ± 0.2 ly
(43.88 ± 0.06 pc)
Details
Mass0.86 ± 0.06[4] M☉
Surface gravity (log g)4.54 ± 0.05[4] cgs
Temperature4920 ± 45[4] K
Metallicity [Fe/H]+0.20[5] dex
Age7.7 ± 2.3[4] Gyr
Other designations
CD−59° 829, HD 27894, HIP 20277, LTT 1953.[3]
Database references
SIMBADdata

In 2005, the Geneva Extrasolar Planet Search Team announced some of the discoveries of an extrasolar planet orbiting the star.[6] In 2017, the discovery of two additional exoplanets was announced. One is very close to the star like the one discovered earlier, while the other one orbits the star at a much larger distance. It is the first system where such a large gap between orbital distances has been found.[7][8]

The HD 27894 planetary system[6]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >0.66 MJ 0.125 18.02 ± 0.02 0.047 ± 0.010 — —
c >0.16 MJ 0.198 36.1 ± 0.2 0.02 ± 0.02 — —
d >5.4 MJ 5.4 5200 ± 100 0.39 ± 0.05 — —

See also
  • List of extrasolar planets

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. Houk, Nancy (1979). Michigan catalogue of two-dimensional spectral types for the HD stars. Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan. Bibcode:1978mcts.book.....H. LCCN 78010745.
  3. "LTT 1953 -- High proper-motion Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-02-05
  4. Trevisan, M.; et al. (November 2011), "Analysis of old very metal rich stars in the solar neighbourhood", Astronomy & Astrophysics, 535: A42, arXiv:1109.6304, Bibcode:2011A&A...535A..42T, doi:10.1051/0004-6361/201016056. See table 13.
  5. Sousa, S. G.; et al. (August 2008), "Spectroscopic parameters for 451 stars in the HARPS GTO planet search program. Stellar [Fe/H] and the frequency of exo-Neptunes", Astronomy and Astrophysics, 487 (1): 373–381, arXiv:0805.4826, Bibcode:2008A&A...487..373S, doi:10.1051/0004-6361:200809698
  6. Moutou, C.; et al. (2005). "The HARPS search for southern extra-solar planets IV. Three close-in planets around HD 2638, HD 27894 and HD 63454". Astronomy and Astrophysics. 439 (1): 367–373. arXiv:1411.7048. Bibcode:2005A&A...439..367M. doi:10.1051/0004-6361:20052826.
  7. Trifonov, T.; Kürster, M.; Zechmeister, M.; Zakhozhay, O. V.; Reffert, S.; Lee, M. H.; Rodler, F.; Vogt, S. S.; Brems, S. S. (2017). "Three planets around HD 27894. A close-in pair with a 2:1 period ratio and an eccentric Jovian planet at 5.4 AU". Astronomy & Astrophysics. 602: L8. arXiv:1706.00509. Bibcode:2017A&A...602L...8T. doi:10.1051/0004-6361/201731044.
  8. Tomasz Nowakowski (June 12, 2017). "Two new massive planets detected around the star HD 27894". Retrieved June 12, 2017.


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