HR 1099

HR 1099
Chart showing the position of the stars in the constellation Taurus
Location of HR 1099 (circled)
Observation data
Epoch J2000      Equinox ICRS
Constellation Taurus
A
Right ascension 03h 36m 47.291s
Declination +00° 35′ 15.94″
Apparent magnitude (V) 5.91
B
Right ascension 03h 36m 46.844s
Declination +00° 35′ 15.93″
Apparent magnitude (V) 8.79
Characteristics
Spectral type K2:Vnk (K1 IV + G5 V + K3 V)
Variable type RS CVn
Astrometry
A
Radial velocity (Rv)−21.24±6.62 km/s
Proper motion (μ) RA: −32.894 mas/yr
Dec.: −161.772 mas/yr
Parallax (π)33.7528±0.0866 mas
Distance96.6 ± 0.2 ly
(29.63 ± 0.08 pc)
Absolute magnitude (MV)3.6
B
Radial velocity (Rv)−15.34±0.18 km/s
Proper motion (μ) RA: −34.359 mas/yr
Dec.: −138.137 mas/yr
Parallax (π)33.8664±0.0226 mas
Distance96.31 ± 0.06 ly
(29.53 ± 0.02 pc)
Absolute magnitude (MV)6.5
Orbit
Period (P)2.83774 d
Semi-major axis (a)10.3 R☉
Eccentricity (e)0.00 (assumed)
Inclination (i)38°
Periastron epoch (T)2,442,767.4 HJD
Argument of periastron (ω)
(secondary)		0.00 (assumed)°
Semi-amplitude (K1)
(primary)		52.6 km/s
Semi-amplitude (K2)
(secondary)		64.1 km/s
Details
Component Aa
Mass1.0 M☉
Radius3.7 R☉
Surface gravity (log g)3.30 cgs
Temperature4,750 K
Metallicity [Fe/H]−0.16 dex
Rotational velocity (v sin i)39 km/s
Component Ab
Mass0.8 M☉
Radius1.1 R☉
Surface gravity (log g)4.26 cgs
Temperature5,500 K
Component B
Mass0.78 M☉
Radius0.78 R☉
Luminosity0.30 L☉
Surface gravity (log g)4.55 cgs
Temperature4,829 K
Metallicity [Fe/H]+0.10 dex
Rotational velocity (v sin i)4.1 km/s
Age2.2 Gyr
Other designations
STF 422, V711 Tau, BD+00°616, GC 4311, HD 22468, HIP 16846, HR 1099, SAO 111291, PPM 146726, ADS 2644, WDS J03368+0035
Database references
SIMBADdata

HR 1099 is a triple star system in the equatorial constellation of Taurus, positioned 11′ to the north of the star 10 Tauri. This system has the variable star designation V711 Tauri, while HR 1099 is the star's identifier from the Bright Star Catalogue. It ranges in brightness from a combined apparent visual magnitude of 5.71 down to 5.94, which is bright enough to be dimly visible to the naked eye. The distance to this system is 96.6 light years based on parallax measurements, but it is drifting closer with a radial velocity of about −15 km/s.

This system was discovered to be a double star by F. G. W. Struve in 1822, with the components A and B having an angular separation of 5.4″. (The separation was measured at 6.7″ in 2016.) R. E. Wilson in 1953 determined that the brighter member of this pair, component A, has a variable radial velocity. In 1963, O. C. Wilson noted that the same component shows very high emission cores in the calcium H and K absorption lines. Follow-up observations by O. C. Wilson in 1964 showed that the hydrogen–α line of component A is fully in emission and it displays moderate broadening due to rotation. He found a stellar classification of K3 V for component B, matching an ordinary K-type main-sequence star.

A light curve for V711 Tauri, plotted from TESS data

Observations during 1974–1975 demonstrated that component A is a spectroscopic binary star system of the RS Canum Venaticorum variable class. Given its average magnitude of around 5.9, it is one of the brighter known variables of this type. No eclipses were observed, but an orbital period of 2.838 days was determined. Most of the emission was found to be coming from the more massive member of this pair. Radio emission from the binary was detected by F. N. Owen in 1976. It was shown to be a soft X-ray source in 1978 using the HEAO 1 satellite.

This double-lined spectroscopic binary system consists of an evolving K-type subgiant and an ordinary G-type main sequence star. The two stars are orbiting so close to each other that their tidal effects are giving them an elliptical shape. The subgiant is filling about 80% of its Roche lobe. The chromosphere of the subgiant is one of the most active known, with a deep convective zone powering the magnetic dynamo. The G-type companion has a shallow convection zone and is less active.

In 1980, significant variations were found in some spectral features related to surface temperature, suggesting the presence of starspots. Doppler imaging confirmed these starspots are associated with the K subgiant. (It was the first cool star to have its surface Doppler imaged.) The evidence suggests that the spots first appear at low latitude then migrated toward the poles. These spots are much larger than they are on the Sun. About 70% of all spots have been observed at latitudes higher than 50°, particularly around the polar region. A polar spot has persisted for at least twenty years.

The baseline apparent magnitudes of the two stars, after subtracting the effects of starspots, is 5.80 and 7.20. Long term monitoring indicates the subgiant has two activity cycles, similar to the 11-year solar cycle. A 5.3±0.1 year cycle is associated with symmetrical flip-flopping of the spotted area between hemispheres. The longer 15–16 year cycle is a periodic variation in the total spot area. The global magnetic field of the star may be precessing with respect to the axis of rotation.

See also

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
  2. 1 2 3 4 5 6 7 Vallenari, A.; et 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. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 3 4 Freund, S.; Robrade, J.; Schneider, P. C.; Schmitt, J. H. M. M. (2018), "The stellar content of the XMM-Newton slew survey", Astronomy and Astrophysics, 614: A125, arXiv:1712.07410, Bibcode:2018A&A...614A.125F, doi:10.1051/0004-6361/201732009, S2CID 59396964.
  4. 1 2 3 4 5 6 7 Vallenari, A.; et 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. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  5. 1 2 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.
  6. 1 2 3 4 5 6 7 8 9 10 Lanza, A. F.; et al. (August 2006), "Long-term starspot evolution, activity cycle, and orbital period variation of V711 Tauri (HR 1099)", Astronomy and Astrophysics, 455 (2): 595–606, Bibcode:2006A&A...455..595L, doi:10.1051/0004-6361:20064847.
  7. 1 2 Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  8. ↑ Strassmeier, K. G.; Bartus, J. (February 2000), "Doppler imaging of stellar surface structure. XII. Rapid spot changes on the RS CVn binary V711 Tauri = HR 1099", Astronomy and Astrophysics, 354: 537–550, Bibcode:2000A&A...354..537S.
  9. 1 2 3 4 5 Donati, J. -F. (January 1999), "Magnetic cycles of HR 1099 and LQ Hydrae", Monthly Notices of the Royal Astronomical Society, 302 (3): 457–481, Bibcode:1999MNRAS.302..457D, doi:10.1046/j.1365-8711.1999.02096.x.
  10. 1 2 3 Donati, J. -F.; et al. (November 2003), "Dynamo processes and activity cycles of the active stars AB Doradus, LQ Hydrae and HR 1099", Monthly Notices of the Royal Astronomical Society, 345 (4): 1145–1186, Bibcode:2003MNRAS.345.1145D, doi:10.1046/j.1365-2966.2003.07031.x.
  11. 1 2 Soubiran, Caroline; et al. (2016), "The PASTEL catalogue: 2016 version", Astronomy & Astrophysics, 591: A118, arXiv:1605.07384, Bibcode:2016A&A...591A.118S, doi:10.1051/0004-6361/201628497, S2CID 119258214.
  12. 1 2 3 4 5 Stassun K.G.; et al. (October 2019), "The revised TESS Input Catalog and Candidate Target List", The Astronomical Journal, 158 (4): 138, arXiv:1905.10694, Bibcode:2019AJ....158..138S, doi:10.3847/1538-3881/ab3467, S2CID 166227927.
  13. ↑ Luck, R. Earle (January 2017), "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants", The Astronomical Journal, 153 (1): 19, arXiv:1611.02897, Bibcode:2017AJ....153...21L, doi:10.3847/1538-3881/153/1/21, S2CID 119511744, 21.
  14. ↑ "HD 22468A". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-01-04.
  15. ↑ "HD 22468B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-01-04.
  16. ↑ Sinnott, Roger W.; Perryman, Michael A. C. (1997), Millennium Star Atlas, vol. 1, Sky Publishing Corporation and the European Space Agency, p. 260, ISBN 0-933346-84-0.
  17. ↑ Mason, Brian D.; et al. (2001), "The Washington Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
  18. ↑ Wilson, O. C. (October 1963), "A Probable Correlation Between Chromospheric Activity and Age in Main-Sequence Stars", Astrophysical Journal, 138: 832, Bibcode:1963ApJ...138..832W, doi:10.1086/147689.
  19. ↑ Wilson, O. C. (August 1964), "Chromospheric Activity and Lithium", Publications of the Astronomical Society of the Pacific, 76 (451): 238, Bibcode:1964PASP...76..238W, doi:10.1086/128091, S2CID 111386087.
  20. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 22 January 2023.
  21. 1 2 Vogt, S. S.; Penrod, G. D. (September 1983), "Doppler imaging of spotted stars : application to the RS Canum Venaticorum star HR 1099", Publications of the Astronomical Society of the Pacific, 95: 565–576, Bibcode:1983PASP...95..565V, doi:10.1086/131208, S2CID 123206530.
  22. 1 2 Bopp, B. W.; Fekel, F. Jr. (September 1976), "HR 1099: a new bright RS CVn variable", Astronomical Journal, 81: 771–774, Bibcode:1976AJ.....81..771B, doi:10.1086/111951, hdl:2152/34302.
  23. ↑ Owen, F. N. (March 1976), Marsden, B. G. (ed.), "HR 1099", IAU Circular (2929): 2, Bibcode:1976IAUC.2929....2O.
  24. ↑ Walter, F.; Charles, P.; Bowyer, S. (August 1978), "Discovery of quiescent X-ray emission from HR 1099, RS CVn", Nature, 274 (5671): 569–570, Bibcode:1978Natur.274R.569W, doi:10.1038/274569b0, S2CID 4206226.
  25. 1 2 Petit, P.; et al. (March 2004), "Magnetic topology and surface differential rotation on the K1 subgiant of the RS CVn system HR 1099", Monthly Notices of the Royal Astronomical Society, 348 (4): 1175–1190, arXiv:astro-ph/0312238, Bibcode:2004MNRAS.348.1175P, doi:10.1111/j.1365-2966.2004.07420.x, S2CID 119463091.
  26. ↑ Ramsey, L. W.; Nations, H. L. (August 1980), "HR 1099 and the starspot hypothesis for RS CVn binaries", Astrophysical Journal, 239: L121–L124, Bibcode:1980ApJ...239L.121R, doi:10.1086/183306.
  27. 1 2 Berdyugina, Svetlana V.; Henry, Gregory W. (April 2007), "Butterfly Diagram and Activity Cycles in HR 1099", Astrophysical Journal, 659 (2): L157–L160, arXiv:astro-ph/0703530, Bibcode:2007ApJ...659L.157B, doi:10.1086/517881, S2CID 14242208.

Further reading