HD 219077

HD 219077 is a faint, yellow-hued star in the southern constellation of Tucana. It has an apparent visual magnitude of +6.12,[2] which is near the lower limit on stars visible to the naked eye. Based upon an annual parallax shift of 34.2337 mas as seen from Earth,[1] it lies 95 light years from the Sun. HD 219077 is moving closer to the Sun with a radial velocity of −31.01,[4] and has a relatively high proper motion.[6]

HD 219077

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Tucana
Right ascension	23^h 14^m 06.5880^s[1]
Declination	–62° 42′ 00.0124″[1]
Apparent magnitude (V)	+6.12[2]
Characteristics
Spectral type	G8 V[3]
B−V color index	0.787[2]
Astrometry
Radial velocity (Rv)	−31.01[4] km/s
Proper motion (μ)	RA: 478.174±0.061[1] mas/yr Dec.: −424.148±0.067[1] mas/yr
Parallax (π)	34.2337 ± 0.0433[1] mas
Distance	95.3 ± 0.1 ly (29.21 ± 0.04 pc)
Absolute magnitude (MV)	+3.78[2]
Details[2]
Mass	1.05±0.02 M☉
Radius	1.91±0.03 R☉
Luminosity (bolometric)	2.66 L☉
Surface gravity (log g)	4.00±0.03 cgs
Temperature	5,362±18 K
Metallicity [Fe/H]	−0.13±0.01 dex
Rotation	49±4 d
Rotational velocity (v sin i)	1.46 km/s
Age	8.9±0.3 Gyr
Other designations
CD−63°1596, HD 219077, HIP 114699, HR 8829[5]
Database references
SIMBAD	data
Exoplanet Archive	data
Extrasolar Planets Encyclopaedia	data

This is an ordinary G-type main-sequence star with a stellar classification of G8 V.[3] It has 1.05 times the mass of the Sun and 1.91 times the Sun's radius. The star is older than the Sun with an estimated age of 8.9 billion years and is spinning slowly with rotation period of around 47 days. It is radiating 2.66 times the Sun's luminosity from its photosphere at an effective temperature of 5,362 K.[2]

Planetary system

From 1998 to 2012, the star was placed under observation using the CORALIE echelle spectrograph at La Silla Observatory. In 2012, the presence of a long-period, wide-orbiting planet was deduced through radial velocity variations. This discovery was published in November of the same year. The estimated mass of the planet is at least ten times that of Jupiter.[2]

The discoverers noted that HD 219077 b is among the "three most eccentric planets with a period larger than 5 years" – along with HD 98649 b and HD 166724 b, also found with CORALIE. The reason for this eccentricity is unknown. They submitted HD 219077 b as a candidate for direct imaging, once it gets out to 11.0 AU at apoastron with 375 milliarcseconds of angular separation as seen from Earth.[2]

The HD 219077 planetary system[7]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	>10.39±0.09 MJ	6.22±0.09	5,501+130 −119	0.770±0.003	—	—

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. Marmier, M.; et al. (2013). "The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planets". Astronomy and Astrophysics. 551. A90. arXiv:1211.6444. Bibcode:2013A&A...551A..90M. doi:10.1051/0004-6361/201219639. S2CID 59467665.
3. Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992.
4. Jofré, E.; et al. (February 2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: 46, arXiv:1410.6422, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, S2CID 53666931, A50.
5. "HD 219077". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-11-08.
6. Rousseau, J. M.; Perie, J. P. (September 1997), "Astrometric positions of stars with high proper motions in the Southern Hemisphere", Astronomy & Astrophysics Supplement Series, 124 (3): 437–439, Bibcode:1997A&AS..124..437R, doi:10.1051/aas:1997201.
7. "hd_27631_b".

External links

• The Extrasolar Planets Encyclopedia: HD 219077