Sextans A Explained
| Sextans A |
| Epoch: | J2000 |
| Type: | IBm[1] |
| Dist Ly: | 4.31 ± 0.13 Mly (1.32 ± 0.04 Mpc)[2] [3] [4] |
| Z: | 324 ± 2 km/s |
| Appmag V: | 11.9 |
| Size V: | 5.9 × 4.9 |
| Constellation Name: | Sextans |
| Notes: | Square in shape |
| Names: | UGCA 205, DDO 75, PGC 29653 |
Sextans A (also known as UGCA 205) is a small dwarf irregular galaxy. It spans about 5000 light-years across, and is located at 4.3 million light-years away, in the outskirts of the Local Group of galaxies, which includes the Milky Way galaxy, and to which Sextans A may or may not belong.
Sextans A has a peculiar square shape. Massive short-lived stars exploded in supernovae that caused more star formation, triggering yet more supernovae, ultimately resulting in an expanding shell. Young blue stars now highlight areas and shell edges high in current star formation, which from the perspective of observers on Earth appears roughly square.[5] The 10.4 m telescope Gran Telescopio Canarias recently observed the OB-type stars that power the giant HII regions.[6]
See also
Notes and References
- Web site: NASA/IPAC Extragalactic Database . Results for Sextans A . 2006-11-18 .
- Dolphin, Andrew E.. etal . March 2003 . Deep Hubble Space Telescope Imaging of Sextans A. II. Cepheids and Distance . The Astronomical Journal . 125 . 3 . 1261–1290 . 10.1086/346279. 2003AJ....125.1261D. astro-ph/0211486 . 116691617 .
- I. D. Karachentsev. V. E. Karachentseva. W. K. Hutchmeier. D. I. Makarov . A Catalog of Neighboring Galaxies . Astronomical Journal . 2004 . 127 . 4 . 2031–2068 . 2004AJ....127.2031K . 10.1086/382905 . abstract. free .
- Karachentsev, I. D.. Kashibadze, O. G. . Masses of the local group and of the M81 group estimated from distortions in the local velocity field . Astrophysics . 2006 . 49 . 1 . 3–18 . 2006Ap.....49....3K . 10.1007/s10511-006-0002-6 . 120973010 .
- Sextans A: A Seemingly Square Galaxy . November 3, 1998 .
- Camacho. I.. Garcia. M.. Herrero. A.. Simón-Díaz. S.. OB stars at the lowest Local Group metallicity. Astronomy & Astrophysics. 2016. en. 585. A82. 10.1051/0004-6361/201425533. 0004-6361. 1510.05408. 2016A&A...585A..82C. 119162797.
