NGC 4639
| NGC 4639 | |
|---|---|
 | |
| 观测资料（J2000 历元） | |
| 星座 | 室女座 |
| 赤经 | 12h 42m 52.4s[2] |
| 赤纬 | +13° 15′ 27″[2] |
| 红移 | 1018 ± 5 km/s[2] |
| 视星等 (V) | 12.2[2] |
| 特征 | |
| 类型 | SA(rs)bc[2] |
| 角直径 (V) | 2′.8 × 1′.9[2] |
| 其他名称 | |
| UGC 7884,[2] PGC 42741[2] | |
NGC 4639是一个位于室女座的棒旋星系，距离地球约7000万光年，是室女座星系团的成员星系之一。该星系中心有超大质量黑洞存在[3]。
距离量测
1990年6月天文学家在NGC 4639内发现Ia超新星SN 1990N。当时NGC 4639也是艾伦·桑德奇的团队使用造父变星进行距离量测最远的星系。桑德奇的团队量测SN 1990N的光度峰值后与其他邻近星系的Ia超新星光度峰值效正值做比较，确认Ia超新星量测是造父变星以外另一个可靠的宇宙距离量测工具，并且可量测距离较造父变星法远数百倍[5]。
参考资料
- ^ Elegant spiral hides a hungry monster. [13 October 2015]. （原始内容存档于2015-12-08）.
- ^ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 NASA/IPAC Extragalactic Database. Results for NGC 4639. [2007-04-01]. （原始内容存档于2011-05-14）.
- ^ Botkin-Kowacki, Eva. Spectacular Hubble photo: A bright galaxy holds a hidden secret. The Christian Science Monitor. 13 October 2015 [14 October 2015]. （原始内容存档于2017-08-30）.
- ^ Ho, Luis C.; Ptak, Andrew; Terashima, Yuichi; Kunieda, Hideyo; Serlemitsos, Peter J..; Yaqoob, Tahir.; Koratkar, Anuradha P. X-Ray Properties of the Weak Seyfert 1 Nucleus in NGC 4639. The Astrophysical Journal. 1999, 525: 168–175. Bibcode:1999ApJ...525..168H.
- ^ Sandage, Allan; Saha, A.; Tammann, G. A.; Labhardt, Lukas; Panagia, N.; Macchetto, F. D. Cepheid Calibration of the Peak Brightness of Type IA Supernovae: Calibration of SN 1990N in NGC 4639 Averaged with Six Earlier Type IA Supernova Calibrations to Give H 0 Directly. Astrophysical Journal Letters. 1999, 460: L15–L18. Bibcode:1996ApJ...460L..15S.
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