HD 49798

HD 49798

繪自「TESS」資料的HD 49798 光變曲線，[1]
觀測資料
曆元 J2000
星座 船尾座
星官
赤經 06h 48m 04.70015s[2]
赤緯 −44° 18′ 58.4360″[2]
視星等（V） 8.287[3]
特性
光谱分类sdO6p
U−B 色指数−1.259[3]
B−V 色指数−0.270[3]
变星类型HMXB[4]
天体测定
徑向速度 (Rv)12.10[5] km/s
自行 (μ) 赤经：−4.162[2] mas/yr
赤纬：5.926[2] mas/yr
视差 (π)1.9196 ± 0.0501[2] mas
距离1,700±46 ly
(521 ± 14 pc)
軌道[6]
繞行週期 (P)1.547666(6) d
半長軸 (a)2,891,000正負15,000公里（0.01933正負0.00010天文單位）
偏心率 (e)0.0
倾斜角 (i)84.5 ± 0.7°
詳細資料
sdO5.5[7]
質量1.41 ± 0.02[6] M☉
半徑1.08 ± 0.06[6] R☉
表面重力 (log g)4.25[8]
亮度3,943[8] L☉
溫度47,500[8] K
WD
質量1.220 ± 0.008[6] M☉
溫度225,000[9] K
自轉13.184246634(7) s[6]
其他命名
HD 49798, CD-44°2920, SAO 218207, HIP 32602, AAVSO 0645-44
參考資料庫
SIMBAD资料

HD 49798是在星座船尾座的一對聯星，與地球的距離約為521正負14秒差距（1,699正負46光年）。它的視星等為8.3，是已知最亮的O型次矮星之一[10]。

HD 49798於1964年被發現為罕見的缺氫O型次矮星，是當時所知最明亮的O型次矮星[11]。這顆星被確認為聯星，但伴星無法在目視或光譜上偵測到[12]。

在HD 49798的附近發現的X射線源RX J0648.0-4418，是只有XMM-牛頓衛星太空望遠鏡能夠辨識的X射線源。它是一顆質量約1.3太陽質量的白矮星，以13秒的軌道週期繞行HD 49798[13]；這個旋轉速度每年加速72.0±0.6 ns[6]。這是從13秒的X射線脈衝中偵測到的，該脈衝是恆星風吸積在緻密天體上的結果[10]。有人提出白矮星被一個岩屑盤包圍著。在此模型中，盤中的物質會透過磁場被引導到白矮星的極區，這解釋了觀測到的X射線脈衝[10]。該系統被認為很可能在數萬年內爆發成為Ia型超新星[14][15]。

參考文獻

  1. ^ MAST: Barbara A. Mikulski Archive for Space Telescopes. Space Telescope Science Institute. [27 December 2024]. 
  2. ^ 2.0 2.1 2.2 2.3 2.4 Brown, A. G. A.; et al. Gaia Early Data Release 3: Summary of the contents and survey properties. Astronomy & Astrophysics. 2021, 649: A1. Bibcode:2021A&A...649A...1G. S2CID 227254300. arXiv:2012.01533 可免费查阅. doi:10.1051/0004-6361/202039657 可免费查阅.  已忽略未知参数|collaboration= (帮助) (勘误: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  3. ^ 3.0 3.1 3.2 Landolt, Arlo U.; Uomoto, Alan K. Optical Multicolor Photometry of Spectrophotometric Standard Stars. The Astronomical Journal. 2007, 133 (3): 768–790. Bibcode:2007AJ....133..768L. S2CID 119672730. arXiv:0704.3030 可免费查阅. doi:10.1086/510485. 
  4. ^ Mereghetti, S.; La Palombara, N.; Tiengo, A.; Sartore, N.; Esposito, P.; Israel, G. L.; Stella, L. X-ray emission from the luminous O-type subdwarf HD 49798 and its compact companion. Astronomy & Astrophysics. 2013, 553: A46. Bibcode:2013A&A...553A..46M. S2CID 56402049. arXiv:1304.1653 可免费查阅. doi:10.1051/0004-6361/201321271. 
  5. ^ Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; Levato, H.; Morrell, N. I.; Torres, G.; Udry, S. SB9: The ninth catalogue of spectroscopic binary orbits. Astronomy and Astrophysics. 2004, 424 (2): 727–732. Bibcode:2004A&A...424..727P. S2CID 119387088. arXiv:astro-ph/0406573 可免费查阅. doi:10.1051/0004-6361:20041213. 
  6. ^ 6.0 6.1 6.2 6.3 6.4 6.5 Rigoselli, Michela; De Grandis, Davide; Mereghetti, Sandro; Malacaria, Christian. Timing the X-ray pulsating companion of the hot subdwarf HD 49798 with NICER. Monthly Notices of the Royal Astronomical Society. 30 May 2023, 523 (2): 3043–3048. arXiv:2305.15845 可免费查阅. doi:10.1093/mnras/stad1611 可免费查阅. 
  7. ^ Mereghetti, S.; Tiengo, A.; Esposito, P.; La Palombara, N.; Israel, G. L.; Stella, L. An Ultramassive, Fast-Spinning White Dwarf in a Peculiar Binary System. Science. 2009, 325 (5945): 1222–1223. Bibcode:2009Sci...325.1222M. PMID 19729650. S2CID 206521141. arXiv:1003.0997 可免费查阅. doi:10.1126/science.1176252. 
  8. ^ 8.0 8.1 8.2 Kudritzki, R. P.; Simon, K. P. Non-LTE analysis of subluminous O-star. The hydrogen-deficient subdwarf O-binary HD 49798. Astronomy and Astrophysics. 1978, 70: 653. Bibcode:1978A&A....70..653K. 
  9. ^ Mereghetti, S.; Pintore, F.; Rauch, T.; La Palombara, N.; Esposito, P.; Geier, S.; Pelisoli, I.; Rigoselli, M.; Schaffenroth, V.; Tiengo, A. New X-ray observations of the hot subdwarf binary HD 49798/RX J0648.0–4418. Monthly Notices of the Royal Astronomical Society. 2021, 504: 920–925. arXiv:2104.03867 可免费查阅. doi:10.1093/mnras/stab1004 可免费查阅. 
  10. ^ 10.0 10.1 10.2 Chen, Wen-Cong. X-ray pulsar HD 49798: A contracting white dwarf with a debris disk?. Astronomy & Astrophysics. 2022, 662: A79. Bibcode:2022A&A...662A..79C. S2CID 248965211. arXiv:2205.09982 可免费查阅. doi:10.1051/0004-6361/202243536. 
  11. ^ Jaschek, Mercedes; Jaschek, Carlos. HD 49798, a New O-Type Subdwarf. Publications of the Astronomical Society of the Pacific. 1963, 75 (445): 365. Bibcode:1963PASP...75..365J. doi:10.1086/127968. 
  12. ^ Thackeray, A. D. The spectroscopic orbit of the O-type subdwarf HD 49798. Monthly Notices of the Royal Astronomical Society. 1970, 150 (2): 215–225. Bibcode:1970MNRAS.150..215T. doi:10.1093/mnras/150.2.215 可免费查阅. 
  13. ^ Bisscheroux, B. C.; Pols, O. R.; Kahabka, P.; Belloni, T.; Van Den Heuvel, E. P. J. The nature of the bright subdwarf HD 49798 and its X-ray pulsating companion. Astronomy and Astrophysics. 1997, 317: 815. Bibcode:1997A&A...317..815B. 
  14. ^ Wang, Bo; Han, Zhanwen. Progenitors of type Ia supernovae. New Astronomy Reviews. 2012, 56 (4): 122. Bibcode:2012NewAR..56..122W. S2CID 118740933. arXiv:1204.1155 可免费查阅. doi:10.1016/j.newar.2012.04.001. 
  15. ^ Liu, Dong-Dong; Zhou, Wei-Hong; Wu, Cheng-Yuan; Wang, Bo. Is the X-ray pulsating companion of HD 49798 a possible type Ia supernova progenitor?. Research in Astronomy and Astrophysics. 2015, 15 (11): 1813. Bibcode:2015RAA....15.1813L. S2CID 118683249. arXiv:1504.01461 可免费查阅. doi:10.1088/1674-4527/15/11/004. 
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