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HD 77191

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HD 77191
Location of HD 77191 (circled)
Observation data
Epoch J2000Ā Ā Ā Ā Ā Ā Equinox ICRS
Constellation Cetus
Right ascension 09h 01m 22.77660s[1]
Declination +10Ā°Ā 43ā€²Ā 58.5175ā€³[1]
ApparentĀ magnitudeĀ (V) 8.83 to 8.87[2]
Characteristics
EvolutionaryĀ stage main sequence[1]
SpectralĀ type G0V[3] + M[4]
Bāˆ’V color index +0.63[5]
Jāˆ’H color index +0.294[6]
Jāˆ’K color index +0.390[6]
VariableĀ type BY Draconis variable[7][2]
Astrometry
Radial velocity (Rv)7.10Ā±0.1[8] km/s
Proper motion (Ī¼) RA:Ā āˆ’12.524[1] mas/yr
Dec.:Ā 4.156[1] mas/yr
Parallax (Ļ€)16.4293Ā±0.0623Ā mas[1]
Distance198.5 Ā± 0.8Ā ly
(60.9 Ā± 0.2Ā pc)
AbsoluteĀ magnitudeĀ (MV)4.83Ā±0.16[4]
Orbit[4]
PrimaryHD 77191 A
SecondaryHD 77191 B
Period (P)44.32Ā±0.29 d
Semi-major axis (a)(9.87Ā±0.10)Ɨ106Ā km (minimum)
Eccentricity (e)0.315Ā±0.008
Inclination (i)105.1Ā±3.5Ā°
Periastron epoch (T)53494.80Ā±0.19
Argument of periastron (Ļ‰)
(secondary)		297.5Ā±2.2Ā°
Details[9]
HD 77191 A
Mass1.01Ā±0.02Ā Mā˜‰
Radius0.93Ā±0.02Ā Rā˜‰
Surface gravity (logĀ g)4.51Ā±0.02Ā cgs
Temperature5785Ā±40Ā K
Metallicity [Fe/H]āˆ’0.02Ā±0.03Ā dex
Rotation10.0Ā±0.2Ā d[4]
Rotational velocity (vĀ sinĀ i)4.5Ā±0.5[4]Ā km/s
Age1.46Ā±1.26Ā Gyr
HD 77191 B
Mass~0.38[4]Ā Mā˜‰
Other designations
HL Cancri, AG+10Ā°1163, BD+11Ā°1961, HD 77191, HIP 44303, SAO 98298, PPM 126017, TIC 323492976, TYC 815-2116-1, GSC 00815-02116, 2MASS J09012277+1043585, Gaia DR3 603701328976020864[10]
Database references
SIMBADHD 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 about 8.8, it is too faint to be seen by the naked eye but observable using binoculars[11] as a yellow-hued dot of light. It is located at a distance of 198.5 light-years (60.9 parsecs) according to Gaia DR3 parallax measurements, and is receding from the Sun at a heliocentric radial velocity of 7.10Ā km/s.

The star is part of the Castor stream,[12] a moving group of young stars that includes some of the brightest stars in the night sky, such as Castor, Fomalhaut, and Vega.[13]

Stellar properties

[edit]
A light curve for HL Cancri, plotted from TESS data.[14] 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 ƅ, indicative of its youth,[7] with an estimated age of 1.46Ā±1.26Ā 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 10.0Ā±0.2Ā d (which is also the star's rotation period).[4] Hence, the star is classified as a BY Draconis variable.[7]

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 Mā˜‰, making it likely a red dwarf.[4]

References

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  1. 1 2 3 4 5 6 Vallenari, A.; etĀ al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CIDĀ 244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085.
  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: 323ā€“325. Bibcode:2005Obs...125..323G.
  5. ā†‘ HĆøg, E.; etĀ al. (February 2000). "The Tycho-2 Catalogue of the 2.5 Million Brightest Stars". Astronomy and Astrophysics. 355 (1): L27ā€“L30. Bibcode:2000A&A...355L..27H.
  6. 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.
  7. 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.
  8. ā†‘ LĆ³pez-Santiago, J.; Montes, D.; GĆ”lvez-Ortiz, M. C.; Crespo-ChacĆ³n, I.; MartĆ­nez-ArnĆ”iz, R. M.; FernĆ”ndez-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. arXiv:1002.1663. Bibcode:2010A&A...514A..97L. doi:10.1051/0004-6361/200913437. ISSNĀ 0004-6361. Retrieved 22 December 2024.
  9. ā†‘ 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. arXiv:1810.01813. Bibcode:2018A&A...619A.130A. doi:10.1051/0004-6361/201834285. ISSNĀ 0004-6361. Retrieved 22 December 2024.
  10. ā†‘ "HD 77191". SIMBAD. Centre de donnĆ©es astronomiques de Strasbourg. Retrieved 22 December 2024.
  11. ā†‘ Zarenski, Ed (2004). "Limiting Magnitude in Binoculars" (PDF). Cloudy Nights. Archived (PDF) from the original on 21 July 2011. Retrieved 6 May 2011.
  12. ā†‘ 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): 421. arXiv:1603.03159. Bibcode:2015BaltA..24..421V. doi:10.1515/astro-2017-0244. ISSNĀ 2543-6376. Record for this source at VizieR.
  13. ā†‘ Mamajek, Eric E.; Bartlett, Jennifer L.; Seifahrt, Andreas (2013). "The Solar Neighborhood XXX: Fomalhaut C". The Astronomical Journal. 146 (6): 154. arXiv:1310.0764. Bibcode:2013AJ....146..154M. doi:10.1088/0004-6256/146/6/154.
  14. ā†‘ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
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