HD 77191

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HD 77191
Cancer constellation map.svg
Red circle.svg
Location of HD 77191 (circled)
Observation data
Epoch J2000 [1]        Equinox J2000 [1]
Constellation Cetus
Right ascension 09h 01m 22.77660s
Declination +10° 43′ 58.5175″
Apparent magnitude  (V)8.88 [2]
Characteristics
Spectral type G0V [3] + M [4]
B−V color index +0.63 [2]
J−H color index +0.294 [5]
J−K color index +0.390 [5]
Variable type BY Draconis variable [6]
Astrometry
Radial velocity (Rv)7.10±0.1 [7]  km/s
Proper motion (μ)RA: −12.524 [1]   mas/yr
Dec.: 4.156 [1]   mas/yr
Parallax (π)16.4293 ± 0.0623  mas [1]
Distance 198.5 ± 0.8  ly
(60.9 ± 0.2  pc)
Absolute magnitude  (MV)4.83±0.16 [4]
Orbit [4]
PrimaryHD 77191 A
CompanionHD 77191 B
Period (P)44.32±0.29 d
Semi-major axis (a)(9.87±0.10)×106 km (minimum)
Eccentricity (e)0.315±0.008
Inclination (i)105.1±3.5°
Periastron epoch (T)53494.80±0.19
Argument of periastron (ω)
(secondary)		297.5±2.2°
Details [8]
HD 77191 A
Mass 1.01±0.02  M☉
Radius 0.93±0.02  R☉
Surface gravity (log g)4.51±0.02  cgs
Temperature 5785±40  K
Metallicity [Fe/H]−0.02±0.03  dex
Rotation 10.0±0.2  d [4]
Rotational velocity (v sin i)4.5±0.5 [4]  km/s
Age 1.46±1.26  Gyr
HD 77191 B
Mass ~0.38 [4]   M☉
Other designations
HL Cancri, AG+10°1163, BD+11°1961, Gaia DR3  603701328976020864, HD  77191, HIP  44303, SAO  98298, PPM  126017, TIC  323492976, TYC  815-2116-1, GSC  00815-02116, 2MASS J09012277+1043585 [9]
Database references
SIMBAD HD 77191

HD 77191 is a spectroscopic binary composed of a Sun-like variable star and a probable red dwarf, [4] located in the zodiac constellation of Cancer. It has the variable-star designation HL Cancri (abbreviated to HL Cnc). With an apparent magnitude of 8.88, it is too faint to be seen by the naked eye but observable using binoculars [10] as a yellow-hued dot of light. It is located at a distance of 198.5 light-years (60.9 parsecs) according to Gaia EDR3 parallax measurements, and is receding farther away from the Sun at a heliocentric radial velocity of 7.10 km/s.

The star is part of the Castor stream, [11] a moving group of young stars that includes some of the brightest stars in the night sky, such as Castor, Fomalhaut, and Vega. [12]

Stellar properties

A light curve for HL Cancri, plotted from TESS data. The 10 day rotation period is marked in red. HLCncLightCurve.png
A light curve for HL Cancri, plotted from TESS data. The 10 day rotation period is marked in red.

The primary star is a G-type main-sequence star with the spectral type G0V, almost identical to the Sun in mass, effective temperature, and metallicity, but approximately 7% smaller in radius. Its spectrum shows clear signs of high stellar activity and a strong lithium doublet spectral line at wavelength 6707.8 Å, indicative of its youth, [6] with an estimated age of 1.46±1.26  Gyr . Accordingly, the star displays large starspots, which are responsible for slight variations in its brightness, first discovered in 2000 [3] with a mean amplitude of about 0.025 mag and a period of 10.0±0.2  d (which is also the star's rotation period). [4] Hence, the star is classified as a BY Draconis variable. [6]

Data collected by Hipparcos suggested that the star was single, [3] but radial velocity observations via the Coravel spectrograph at the University of Cambridge yielded a 44-day period orbit for a binary companion. By matching the primary's rotational velocities measured through Doppler broadening and its photometric period, the mass of the unseen secondary star is placed at roughly 0.38 M☉, making it likely a red dwarf. [4]

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<span class="mw-page-title-main">RS Sagittarii</span> Eclipsing binary star system in the constellation Sagittarius

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References

  1. 1 2 3 4 5 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. 1 2 Høg, E.; et al. (February 2000). "The Tycho-2 Catalogue of the 2.5 Million Brightest Stars". Astronomy and Astrophysics. 355 (1): L27–L30. Bibcode:2000A&A...355L..27H.
  3. 1 2 3 Lebzelter, T. (5 September 2000). "HD 77191: Another Variable Solar Twin". Information Bulletin on Variable Stars. 4949 (1). Konkoly Observatory, Budapest: International Astronomical Union. Bibcode:2000IBVS.4949....1L.
  4. 1 2 3 4 5 6 7 8 9 Griffin, R. F. (October 2005). "The BY Dra Star HD 77191 Is a Spectroscopic Binary, but GQ Leo May Not Be". The Observatory . 125: 323–325. Bibcode:2005Obs...125..323G.
  5. 1 2 Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  6. 1 2 3 Dall, T. H. (9 December 2004). "Spectroscopic Confirmation of Three Suspected BY Dra Variables". Information Bulletin on Variable Stars. 5581 (1). Konkoly Observatory, Budapest: International Astronomical Union. Bibcode:2004IBVS.5581....1D.
  7. ↑ López-Santiago, J.; Montes, D.; Gálvez-Ortiz, M. C.; Crespo-Chacón, I.; Martínez-Arnáiz, R. M.; Fernández-Figueroa, M. J.; de Castro, E.; Cornide, M. (2010). "A high-resolution spectroscopic survey of late-type stars: chromospheric activity, rotation, kinematics, and age" (PDF). Astronomy and Astrophysics. 514: A97. doi: 10.1051/0004-6361/200913437 . ISSN   0004-6361 . Retrieved 22 December 2024.
  8. ↑ Adibekyan, V.; de Laverny, P.; Recio-Blanco, A.; Sousa, S. G.; Delgado-Mena, E.; Kordopatis, G.; Ferreira, A. C. S.; Santos, N. C.; Hakobyan, A. A.; Tsantaki, M. (2018). "The AMBRE project: searching for the closest solar siblings" (PDF). Astronomy & Astrophysics. 619: A130. doi: 10.1051/0004-6361/201834285 . ISSN   0004-6361 . Retrieved 22 December 2024.
  9. ↑ "HD 77191". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 22 December 2024.
  10. ↑ Zarenski, Ed (2004). "Limiting Magnitude in Binoculars" (PDF). Cloudy Nights. Archived (PDF) from the original on 21 July 2011. Retrieved 6 May 2011.
  11. ↑ Vereshchagin, S. V.; Chupina, N. V. (1 January 2015). "Details of the Spatial Structure and Kinematics of the Castor and Ursa Major Streams". Open Astronomy. 24 (4). doi: 10.1515/astro-2017-0244 . ISSN   2543-6376 . Retrieved 22 December 2024. Record for this source at VizieR.
  12. ↑ Mamajek, Eric E.; Bartlett, Jennifer L.; Seifahrt, Andreas (2013). "The Solar Neighborhood XXX: Fomalhaut C". The Astronomical Journal . 146: 154. arXiv: 1310.0764 . Bibcode:2013AJ....146..154M. doi:10.1088/0004-6256/146/6/154.
  13. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
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