Leo A
| Galaxy Leo A |
|
|---|---|
|
|
| Admission of Leo A of the HST | |
| AladinLite | |
| Constellation | lion |
|
Position equinox : J2000.0 , epoch : J2000.0 |
|
| Right ascension | 09 h 59 m 26.4 s |
| declination | 30 ° 44 ′ 47 ″ |
| Appearance | |
| Morphological type | (d) IBm V-VI |
| Brightness (visual) | 12.59 likes |
| Brightness (B-band) | 12.80 mag |
| Angular expansion | 5 ′, 1 × 3 ′, 1 |
| Physical data | |
| Affiliation | Local group |
| Radial velocity | 24 ± 4 km / s |
| distance | (2,250,000 ± 200,000) ly / (690,000 ± 60,000) pc |
| Absolute brightness | (−11.54 ± 0.03) mag |
| Dimensions | (8.0 ± 2.7) × 10 7 M ☉ |
| diameter | 2,900 ly × 4,600 ly |
| history | |
| discovery | Fritz Zwicky |
| Discovery date | 1942 |
| Catalog names | |
| UGC 5364 • PGC 28868 • CGCG 153-010 • MCG + 05-24-008 • Leo III, DDO 69 | |
Leo A (also known as Leo III is known) an irregular galaxy of Hubble type (d) IBM V-VI in the constellation of the lion on the ecliptic . The member of the local group was discovered by Fritz Zwicky in 1942 .
properties
Sizes
Leo A is at a distance of about 690 k pc from our solar system and is moving away from our sun at a speed of about 15 km / s . It is relatively isolated from other local group galaxies. The mass can be estimated to be about (8.0 ± 2.7) × 10 7 M ⊙ with a proportion of at least 80% dark matter .
Age
Leo A is one of the most isolated galaxies in the Local Group and has shown no signs of interaction or merging with other galaxies for billions of years. The presence of RR Lyrae stars shows that Leo A has a very ancient star population, up to 10 billion years old.
composition
The neutral hydrogen of the galaxy shows a spatial expansion corresponding to the optical size of the dwarf galaxy and condenses to form an uneven ring. The galaxy does not rotate and the hydrogen gas moves around in random clusters. The proportion of heavier elements is only one to two percent of that of our sun , which indicates a significantly lower stellar development compared to our Milky Way. Leo A shows signs of increased star formation a few billion years ago, but the current rate of star formation is low. There are four H-II regions there, stimulated by short-lived stars of the spectral class O.
Web links
- astronews.com: Picture of the day April 14, 2016
Individual evidence
- ↑ SIMBAD Astronomical Database . In: Results for Leo III Dwarf . Retrieved February 7, 2010.
- ↑ a b c d e f g h NED
- ↑ ID Karachentsev, VE Karachentseva, WK Hutch Meier, DI Makarov: A Catalog of Neighboring Galaxies . In: Astronomical Journal . 12745345, No. 4, 2004, pp. 2031-2068. bibcode : 2004AJ .... 127.2031K . doi : 10.1086 / 382905 .
- ↑ Karachentsev, ID; Kashibadze, OG: Masses of the local group and of the M81 group estimated from distortions in the local velocity field . In: Astrophysics . 49, No. 1, 2006, pp. 3-18. bibcode : 2006Ap ..... 49 .... 3K . doi : 10.1007 / s10511-006-0002-6 .
- ^ F Zwicky: On the Large Scale Distribution of Matter in the Universe . In: Physical Review . 61, No. 7-8, April 1942, pp. 489-503. bibcode : 1942PhRv ... 61..489Z . doi : 10.1103 / PhysRev.61.489 .
- ↑ Brown, Warren R., et al .: Stellar Velocity Dispersion of the Leo A Dwarf Galaxy . In: The Astrophysical Journal . 666, No. 1, September 2007, pp. 231-235. arxiv : 0705.1093 . bibcode : 2007ApJ ... 666..231B . doi : 10.1086 / 519547 .
- ↑ Vansevičius, Vladas, et al . The full-fledged Dwarf Irregular Galaxy Leo A . In: The Astrophysical Journal . 611, No. 2, August 2008, pp. L93-L96. arxiv : astro-ph / 0405313 . bibcode : 2004ApJ ... 611L..93V . doi : 10.1086 / 423802 .
- ↑ Young, LM; Lo, KY: The Neutral Interstellar Medium in Nearby Dwarf Galaxies. I. Leo A . In: Astrophysical Journal . 462, 1996, pp. 203-214. bibcode : 1996ApJ ... 462..203Y . doi : 10.1086 / 177141 .