天囷增廿一

天囷增廿一（HR 1099）是位於黃道星座金牛座的一個三合星系統，位置在恆星天囷增十五（金牛座10）以北6997319977029532294♠11′^[15]。該系統有變星名稱金牛座V711，而HR 1099是「亮星星表」中的恆星識別字。它的視星等亮度組合範圍從5.71到5.94^[6]，其亮度用肉眼隱約可見。基於視差量測，到該系統的距離為96.6光年^[1]，但它正在以大約−15 km/s的徑向速度向接近太陽系的方向漂移。

天囷增廿一（HR 1099）

以紅圈標示天囷增廿一（HR 1099）的位置。
觀測數據 曆元 J2000      分點 J2000
星座	金牛座
A
赤經	03h 36m 47.291s[1]
赤緯	00° 35′ 15.94″[1]
視星等 (V)	5.91[2]
B
赤經	03h 36m 46.844s[3]
赤緯	00° 35′ 15.93″[3]
視星等 (V)	8.79[2]
特性
光譜分類	K2:Vnk[4] (K1 IV + G5 V + K3 V)[5]
變星類型	RS CVn[6]
天體測定
A
徑向速度 (Rv)	−21.24+6.62 −[1] km/s
自行 (μ)	赤經：−32.894 mas/yr 赤緯：−161.772 mas/yr
視差 (π)	33.7528 ± 0.0866[1] mas
距離	96.6 ± 0.2 ly (29.63 ± 0.08 pc)
絕對星等 (MV)	3.6[2]
B
徑向速度 (Rv)	2998846600000000000♠−15.34±0.18[3] km/s
自行 (μ)	赤經：−34.359 mas/yr 赤緯：−138.137 mas/yr
視差 (π)	33.8664 ± 0.0226[3] mas
距離	96.3 ± 0.2 ly (29.53 ± 0.02 pc)
絕對星等 (MV)	6.5[2]
軌道[7]
繞行週期 (P)	2.83774 d
半長軸 (a)	7001103000000000000♠10.3 R☉[8]
偏心率 (e)	0.00 (assumed)
傾斜角 (i)	38[9]°
近心點 曆元 (T)	7006244276740000000♠2,442,767.4 HJD
近心點幅角 (ω) (secondary)	0.00 (assumed)°
半振幅 (K1) (primary)	52.6 km/s
半振幅 (K2) (secondary)	64.1 km/s
詳細資料
成員 Aa
質量	1.0[8] M☉
半徑	3.7[8] R☉
表面重力 (log g)	3.30[5]
溫度	4,750[5] K
金屬量 [Fe/H]	−0.16[10] dex
自轉速度 (v sin i)	39[9] km/s
成員 Ab
質量	0.8[8] M☉
半徑	1.1[8] R☉
表面重力 (log g)	4.26[5]
溫度	5,500[5] K
成員 B
質量	0.78[11] M☉
半徑	0.78[11] R☉
表面重力 (log g)	4.55[11]
亮度	0.30[11] L☉
溫度	4,829[11] K
金屬量 [Fe/H]	+0.10[10] dex
自轉速度 (v sin i)	4.1[12] km/s
年齡	2.2[3] Gyr
其他命名
STF 422、​V711 Tau、​BD+00°616、​GC 4311、​HD 22468、​HIP 16846、​HR 1099、​SAO 111291、​PPM 146726、​ADS 2644、​WDS J03368+0035[13][14]
參考資料庫
SIMBAD	資料

金牛座V771

1822年，弗里德里希·馮·斯特魯維發現該系統是一顆雙星，其中A和B分量的角距離為6995261799387799150♠5.4″。（2016年測量的角距離為6995324825166343389♠6.7″。）^[16]。拉爾夫·埃爾默·威爾遜（英語：Ralph Elmer Wilson）在1953年確定，這對中較亮的成員A，具有可變的徑向速度。1963年，奧林·查多克·威爾遜（英語：Olin Chaddock Wilson）指出，相同的成員在鈣H和K吸收線中顯示出非常高的發射核^[17]。奧林·查多克·威爾遜在1964年的後續觀察表明，成員A的氫-α線完全處於發射狀態，並且由於旋轉而顯示出適度的加寬。他發現成員B的恆星光譜分類為K3V，與一顆普通的K型主序星相匹配^[18]。

根據「TESS」數據繪製的天囷增廿一（金牛座V711）的光變曲線^[19]。

1974年至1975年的觀測表明，成員A是獵犬座RS型變星類的光譜聯星恆星系統。考慮到它的平均星等約為5.9，它是這類已知較亮的變星之一^[20]。沒有觀測到食，但確定了2.838天的軌道週期。大部分發射被發現來自這對中質量較大的成員^[21]。1976年，弗雷澤·納爾遜·歐文（英語：Frazer Nelson Owen）探測到了該聯星的電波發射^[22]。1978年使用HEAO1（英語：High Energy Astronomy Observatory 1）衛星證明它是軟X射線源^[23]。

這個雙線光譜聯星系統由一顆演化中的K型次巨星和一顆普通的G型主序星組成。這兩顆恆星的軌道距離如此之近，以至於它們的潮汐效應使它們呈橢圓形。該次巨星正在填充其洛希瓣的大約80%^[5]。次巨星的色球層是已知的最活躍的磁活動之一，有一個很深的對流區為磁發電機供電^[24][4]。G型伴星不太活躍，有一個淺對流區^[5]。

1980年，在一些與表面溫度有關的光譜特徵中發現了顯著的變化，表明存在星斑^[25]。都卜勒成像（英語：Doppler imaging）證實這些多少與K型次巨星有關（它是第一顆對其表面進行都卜勒成像的低溫恆星^[26]。）。證據表明，這些斑點首先出現在低緯度地區，然後向兩極遷移^[20]。這些斑點比太陽上的要大得多^[5]，大約70%的斑點是在緯度高於50°的地方觀測到的，尤其是在極地地區^[9][24]。一個極地斑點已經存在了至少二十年^[5]。

減去星斑的影響後，這兩顆恆星的基線視星等分別為5.80和7.20^[5]。長期監測表明，次巨星有兩個活動週期，類似於11年的太陽週期。一個7008167255280000000♠5.3±0.1 年週期與半球之間斑點區域的對稱翻轉有關。較長的15-16年週期是總斑點面積的週期性變化。恆星的整體磁場可能是相對於自轉軸的進動^[26]。

相關條目

• 白羊座UX^[21]

參考資料

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進階讀物

• Perdelwitz, V.; et al, Long-term variations in the X-ray activity of HR 1099, Astronomy & Astrophysics, August 2018, 616: A161, Bibcode:2018A&A...616A.161P, S2CID 55130058, arXiv:1806.03033 , doi:10.1051/0004-6361/201732222, A161.
• Osten, Rachel A.; et al, A Multiwavelength Perspective of Flares on HR 1099: 4 Years of Coordinated Campaigns, Astrophysical Journal Supplement Series, July 2004, 153 (1): 317–362, Bibcode:2004ApJS..153..317O, S2CID 119522693, arXiv:astro-ph/0402613 , doi:10.1086/420770.
• Ransom, R. R.; et al, Possible Corotation of the Milliarcsecond Radio Structure of the Close Binary HR 1099, Astrophysical Journal, June 2002, 572 (1): 487–502, Bibcode:2002ApJ...572..487R, S2CID 120225374, doi:10.1086/340300 .
• Ayres, Thomas R.; et al, Chandra, EUVE, HST, and VLA Multiwavelength Campaign on HR 1099: Instrumental Capabilities, Data Reduction, and Initial Results, Astrophysical Journal, March 2001, 549 (1): 554–577, Bibcode:2001ApJ...549..554A, S2CID 15938906, doi:10.1086/319051 .
• Brinkman, A. C.; et al, First light measurements with the XMM-Newton reflection grating spectrometers: Evidence for an inverse first ionisation potential effect and anomalous Ne abundance in the Coronae of HR 1099, Astronomy and Astrophysics, January 2001, 365: L324–L328, Bibcode:2001A&A...365L.324B, S2CID 15848464, arXiv:astro-ph/0011018 , doi:10.1051/0004-6361:20000047.
• Audard, M.; et al, The XMM-Newton view of stellar coronae: Flare heating in the coronae of HR 1099, Astronomy and Astrophysics, January 2001, 365: L318–L323, Bibcode:2001A&A...365L.318A, doi:10.1051/0004-6361:20000085.
• Vogt, Steven S.; et al, Doppler Imagery of the Spotted RS CVn Star HR 1099 (= V711 Tau) from 1981 - 1992, Astrophysical Journal Supplement Series, April 1997, 121: 547, Bibcode:1997astro.ph..4191V, S2CID 119515171, arXiv:astro-ph/9704191 , doi:10.1086/313195.
• Trigilio, C.; et al, VLBI observations of a strong radio flare in HR 1099, Monthly Notices of the Royal Astronomical Society, February 1993, 260 (4): 903–907, Bibcode:1993MNRAS.260..903T, doi:10.1093/mnras/260.4.903 .
• Donati, J. -F.; et al, Photospheric imaging of the RS CVn system HR 1099., Astronomy and Astrophysics, November 1992, 265: 682–700, Bibcode:1992A&A...265..682D.
• Donati, J. -F.; et al, Detection of a magnetic region of HR 1099, Astronomy and Astrophysics, June 1990, 232: L1–L4, Bibcode:1990A&A...232L...1D.
• Rodono, M.; et al, Rotational modulation and flares on RS CVn and BY DRA stars. III. IUEobserations of V711 Tau = (HR 1099), II Peg and AR Lac, Astronomy and Astrophysics, April 1987, 176: 267–284, Bibcode:1987A&A...176..267R.
• Lestrade, J. F.; et al, Detection of a sub-milliarcsecond radio component in the RS CVn system HR 1099, Astrophysical Journal, July 1984, 282: L23–L26, Bibcode:1984ApJ...282L..23L, doi:10.1086/184296 .
• Fekel, F. C., Jr., Spectroscopy of V711 Tauri (= HR 1099) : fundamental properties and evidence for starspots, Astrophysical Journal, May 1983, 268: 274–281, Bibcode:1983ApJ...268..274F, doi:10.1086/160952 .
• Dorren, J. D.; et al, Starspots on V711 Tauri (HR 1099), Astronomical Journal, April 1981, 86: 572–582, Bibcode:1981AJ.....86..572D, doi:10.1086/112918.
• Brown, R. L.; Crane, P. C., On the rapidly variable circular polarization of HR 1099 at radio frequencies, Astronomical Journal, December 1978, 83: 1504–1509, Bibcode:1978AJ.....83.1504B, doi:10.1086/112352.
• Feldman, P. A.; et al, Discovery of a strong radio flaring from HR 1099, Astronomical Journal, December 1978, 83: 1471–1484, Bibcode:1978AJ.....83.1471F, doi:10.1086/112346 .
• Bopp, B. W.; Talcott, J. C., Survey of Halpha emission in V711 Tau (HR 1099) and related Ca II emission binaries, Astronomical Journal, December 1978, 83: 1517–1521, Bibcode:1978AJ.....83.1517B, doi:10.1086/112355 .
• Gibson, D. M.; et al, VLA observations of HR 1099 during the 1977 international campaign, Astronomical Journal, December 1978, 83: 1495–1498, Bibcode:1978AJ.....83.1495G, doi:10.1086/112350 .
• Weiler, E. J.; et al, Coordinated ultraviolet, optical, and radio observations of HR 1099 and UX Arietis, Astrophysical Journal, August 1980, 239: L121–L124, Bibcode:1980ApJ...239L.121R, doi:10.1086/183306.
• Owen, F. N.; et al, The detection of radio emission from the RS CVn binary HR 1099, Astrophysical Journal, November 1976, 210: L27–L30, Bibcode:1976ApJ...210L..27O, doi:10.1086/182295 .