PG 1159星

维基百科,自由的百科全书
跳转至: 导航搜索

PG 1159星,通常也稱為前簡併星[1],是一顆大氣層的不足夠,而中心正在轉變成為行星狀星雲和高熱白矮星恆星。這些恆星非常熱,表面溫度在75,000K至200,000K[2],並且特徵是大氣層只有少量的的吸收譜線;它們的表面重力介於104和106m/Sec2。有些PG 1159星還在進行氦融合[3], § 2.1.1, 2.1.2, Table 2.。PG 1159星是依據它們的原型,PG 1159-035命名的,這顆恆星是在帕洛馬綠色巡天調查紫外線過量時發現的天體 [4],是被發現的第一顆PG 1159星。

人們認為PG 1159星的大氣層之所以奇怪是因為已經流失了,在它們進入漸近巨星分支之後,它們只留下氦融合的核心。結果是,PG 1159星的大氣層混合了其前身AGB形態時的氫和氦燃燒殼層的物質[3], §1.他們認為最終將流失質量、變冷,和成為DO白矮星[2][5], §4.

有些PG 1159恆星非常明亮。由於在本身內部的引力波在非徑向方向上的脈動,使它們的光度有著輕微的變化(5-10%)。它們同時有多種振動模式,典型的周期在300至3,000秒[6][7], Table 1.。 第一顆知道的這一種恆星也是PG 1159-35,在1979年發現這種變化[8],並且在1985年將這種變化標示為室女座GW [9],因此也稱為室女座GW星,並將之作為原型,同時這一類型還可以分為 DOVPNNV[7], § 1.1;[10]

相關條目[编辑]

參考資料[编辑]

  1. ^ Jaschek & Jaschek: CARBON C
  2. ^ 2.0 2.1 Observational constraints on the evolutionary connection between PG 1159 stars and DO white dwarfs, S. D. Huegelmeyer, S. Dreizler, K. Werner, J. Krzesinski, A. Nitta, and S. J. Kleinman. arXiv:astro-ph/0610746.
  3. ^ 3.0 3.1 The Elemental Abundances in Bare Planetary Nebula Central Stars and the Shell Burning in AGB Stars, Klaus Werner and Falk Herwig, Publications of the Astronomical Society of the Pacific 118, #840 (February 2006), pp. 183–204
  4. ^ The Palomar-Green catalog of ultraviolet-excess stellar objects, R. F. Green, M. Schmidt, and J. Liebert, Astrophysical Journal Supplement 61 (June 1986), pp. 305–352. CDS ID II/207.
  5. ^ Determination of Mass-Loss Rates of PG 1159 Stars from Far-Ultraviolet Spectroscopy, Lars Koesterke and Klaus Werner, Astrophysical Journal 500 (June 1998), pp. L55–L59.
  6. ^ Asteroseismology of white dwarf stars, D. E. Winget, Journal of Physics: Condensed Matter 10, #49 (December 14, 1998), pp. 11247–11261. DOI 10.1088/0953-8984/10/49/014.
  7. ^ 7.0 7.1 Mapping the Instability Domains of GW Vir Stars in the Effective Temperature-Surface Gravity Diagram, Quirion, P.-O., Fontaine, G., Brassard, P., Astrophysical Journal Supplement Series 171 (2007), pp. 219–248.
  8. ^ PG1159-035: A new, hot, non-DA pulsating degenerate, J. T. McGraw, S. G. Starrfield, J. Liebert, and R. F. Green, pp. 377–381 in White Dwarfs and Variable Degenerate Stars, IAU Colloquium #53, ed. H. M. van Horn and V. Weidemann, Rochester: University of Rochester Press, 1979.
  9. ^ The 67th Name-List of Variable Stars, P. N. Kholopov, N. N. Samus, E. V. Kazarovets, and N. B. Perova, Information Bulletin on Variable Stars, #2681, March 8, 1985.
  10. ^ §1, Detection of non-radial g-mode pulsations in the newly discovered PG 1159 star HE 1429-1209, T. Nagel and K. Werner, Astronomy and Astrophysics 426 (2004), pp. L45–L48.

Template:White dwarf