خماسية ستفان
Stephan's Quintet | |
---|---|
Credit: HST | |
بيانات الرصد (الحقبة J2000) | |
الكوكبة | Pegasus |
الصعود المستقيم | 22h 35m 57.5s |
الميل | +33° 57′ 36″ |
ألمع عضو | NGC 7318B |
عدد المجرات | 5 |
أسماء أخرى | |
HCG 92, Arp 319, VV 288, SQ | |
انظر أيضاً: مجموعات وعناقيد المجرات، قائمة عناقيد المجرات | |
خماسية ستفان Stephan's Quintet is a visual grouping of five galaxies of which four form the first compact galaxy group ever discovered. The group, visible in the constellation Pegasus, was discovered by Édouard Stephan in 1877 at the Marseille Observatory. The group is the most studied of all the compact galaxy groups. The brightest member of the visual grouping is NGC 7320 that is shown to have extensive H II regions, identified as red blobs, where active star formation is occurring.
الوصف
Four of the five galaxies in Stephan's Quintet form a physical association, Hickson Compact Group 92, and will likely merge with each other. Radio observations in the early 1970s revealed a mysterious filament of emission which lies in inter-galactic space between the galaxies in the group. This same region is also detected in the faint glow of ionized atomic hydrogen seen in the visible part of the spectrum as a green arc.
Two space telescopes have recently provided new insight into the nature of the filament, which is now believed to be a giant intergalactic shock-wave (similar to a sonic boom but traveling in intergalactic gas rather than air) caused by one galaxy (NGC 7318B) falling into the center of the group at several millions of kilometers per hour.
مصدر الآشعة السينية
As NGC 7318B collides with gas in the group, a huge shock wave bigger than the Milky Way spreads throughout the medium between the galaxies, heating some of the gas to temperatures of millions of degrees where they emit X-rays detectable with the NASA Chandra X-ray Observatory.[]
انبعاث الهيدروجين الجزيئي
الانزياح الأحمر
NGC 7320 indicates a small redshift (790 km/s) while the other four exhibit large redshifts (near 6600 km/s). Since galactic redshift is proportional to distance, NGC 7320 is only a foreground projection and is ~39 million lightyears from Earth versus the 210-340 million lightyears of the other five.
NGC 7319 has a type 2 Seyfert nucleus.
A sixth galaxy, NGC 7320C, probably belongs to the Hickson association: it has a redshift similar to the Hickson galaxies, and a tidal tail appears to connect it with NGC 7319.
Name | Type | R.A. (J2000) | Dec. (J2000) | Redshift (km/s) | Apparent Magnitude |
---|---|---|---|---|---|
NGC 7317 | E4 | 22h 35m 51.9s | +33° 56′ 42″ | 6599 ± 26 | +14.6 |
NGC 7318a (UGC 12099) |
E2 pec | 22h 35m 56.7s | +33° 57′ 56″ | 6630 ± 23 | +14.3 |
NGC 7318b (UGC 12100) |
SB(s)bc pec | 22h 35m 58.4s | +33° 57′ 57″ | 5774 ± 24 | +13.9 |
NGC 7319 | SB(s)bc pec | 22h 36m 03.5s | +33° 58′ 33″ | 6747 ± 7 | +14.1 |
NGC 7320c | (R)SAB(s)0/a | 22h 36m 20.4s | +33° 59′ 06″ | 5985 ± 9 | +16.7 |
انظر أيضاً
- سداسية سيفرت Seyfert's Sextet
- رباعية روبرت Robert's Quartet
- NGC 7331 Group
الهامش
- ^ "NASA/IPAC Extragalactic Database". Results for HCG 92. Retrieved 2006-09-18.
- ^ Moles, M.; Marquez, I.; Sulentic, J. W. (1998). "The observational status of Stephan's Quintet". Astronomy and Astrophysics. 334: 473–481. arXiv:astro-ph/9802328. Bibcode:1998A&A...334..473M.
- ^ Stephan, M. E. (1877). "Nebulæ (new) discovered and observed at the observatory of Marseille, 1876 and 1877, M. Stephan". Monthly Notices of the Royal Astronomical Society. 37: 334–339. Bibcode:1877MNRAS..37..334S. doi:10.1093/mnras/37.6.334.
- ^ "NASA/IPAC Extragalactic Database". Results for various galaxies. Retrieved 2006-10-20.
المراجع
- A Shocking Surprise in Stephan's Quintet. 2 March 2006.عشرة March 2006 NASA/JPL-Caltech/Max-Planck Institute/P. Appleton article
- P.N. Appleton, K.C. Xu, W. Reach, M.A. Dopita, Y. Gao, N. Lu, C.C. Popescu, J.W. Sulentic, R.J. Tuffs, and M.S. Yun. Powerful High-Velocity Dispersion Molecular Hydrogen Associated with an Intergalactic Shock Wave in Stephan's Quintet, The Astrophysical Journal, 639:L51-L54, ثلاثة March 2006.عشرة March 2006 Gigantic cosmic cataclysm in Stephan's Quintet of galaxies
- Stephan's Quintet.عشرة March 2006 University of Alabama Astronomy
- Stephan's Quintet: Intruder Galaxy Shocks Tightly-Knit Group.ثمانية May 03.عشرة March 2006 Chandra X-Ray Observatory
- Stephan's Quintet, photo and description from the National Optical Astronomy Observatory. Links to a labeled locator photo.
وصلات خارجية
- GALEX: Stephan's Quintet and NGC 7331
- Star Clusters Born in the Wreckage of Cosmic Collisions
- News Release at ESA/Hubble
- Stephan's Quintet
- NightSkyInfo.com : Stephan's Quintet
- What's Behind Stephan's Quintet? Peter Edmonds, Chandra Blog, 21 July 2009
- Astronomy Picture of the Day on Stephan's Quintet: 13 Nov 2000 12 Aug 2003 11 Sep 2009
- خماسية ستفان on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images