Английская Википедия:HR 1099

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Шаблон:Short description Шаблон:Starbox begin Шаблон:Starbox image Шаблон:Starbox observe 2s Шаблон:Starbox character Шаблон:Starbox astrometry Шаблон:Starbox orbit Шаблон:Starbox detail Шаблон:Starbox detail Шаблон:Starbox catalog Шаблон:Starbox reference Шаблон:Starbox end

HR 1099 is a triple star system in the equatorial constellation of Taurus, positioned Шаблон:Val to the north of the star 10 Tauri.[1] 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,[2] 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,[3] 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 Шаблон:Val. (The separation was measured at Шаблон:Val in 2016.)[4] 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.[5] 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.[6]

Файл:V711TauLightCurve.png
A light curve for V711 Tauri, plotted from TESS data[7]

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.[8] 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.[9] Radio emission from the binary was detected by F. N. Owen in 1976.[10] It was shown to be a soft X-ray source in 1978 using the HEAO 1 satellite.[11]

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.[12] The chromosphere of the subgiant is one of the most active known, with a deep convective zone powering the magnetic dynamo.[13][14] The G-type companion has a shallow convection zone and is less active.[12]

In 1980, significant variations were found in some spectral features related to surface temperature, suggesting the presence of starspots.[15] Doppler imaging confirmed these starspots are associated with the K subgiant. (It was the first cool star to have its surface Doppler imaged.[16]) The evidence suggests that the spots first appear at low latitude then migrated toward the poles.[8] These spots are much larger than they are on the Sun.[12] About 70% of all spots have been observed at latitudes higher than 50°, particularly around the polar region.[17][13] A polar spot has persisted for at least twenty years.[12]

The baseline apparent magnitudes of the two stars, after subtracting the effects of starspots, is 5.80 and 7.20.[12] Long term monitoring indicates the subgiant has two activity cycles, similar to the 11-year solar cycle. A Шаблон:Val 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.[16]

See also

Шаблон:-

References

Шаблон:Reflist

Further reading

Шаблон:Div col

Шаблон:Div col end

Шаблон:Stars of Taurus

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  1. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Sinnott1997 не указан текст
  2. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Samus_et_al_2017 не указан текст
  3. ↑ Ошибка цитирования Неверный тег <ref>; для сносок GaiaDR3 не указан текст
  4. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Mason_et_al_2001 не указан текст
  5. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Wilson_1963 не указан текст
  6. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Wilson_1964 не указан текст
  7. ↑ Ошибка цитирования Неверный тег <ref>; для сносок MAST не указан текст
  8. ↑ 8,0 8,1 Ошибка цитирования Неверный тег <ref>; для сносок Vogy_Penrod_1983 не указан текст
  9. ↑ 9,0 9,1 Ошибка цитирования Неверный тег <ref>; для сносок Bopp_Fekel_1976 не указан текст
  10. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Owen_1976 не указан текст
  11. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Walter_et_al_1978 не указан текст
  12. ↑ 12,0 12,1 12,2 12,3 12,4 Ошибка цитирования Неверный тег <ref>; для сносок Lanza_et_al_2006 не указан текст
  13. ↑ 13,0 13,1 Ошибка цитирования Неверный тег <ref>; для сносок Petit_et_al_2004 не указан текст
  14. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Gray_et_al_2006 не указан текст
  15. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Ramsey_Nations_1980 не указан текст
  16. ↑ 16,0 16,1 Ошибка цитирования Неверный тег <ref>; для сносок Berdyugina_Henry_2007 не указан текст
  17. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Donati_et_al_2003 не указан текст
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