gjdonatiello
Regulus and the dwarf spheroidal galaxy Leo I
Regulus and the dwarf spheroidal galaxy Leo I
Credit: Giuseppe Donatiello
RA 10h 08m 22.311s DEC +11° 58′ 01.95″
Regulus, α Leonis (α Leo), is the brightest star in Leo and one of the brightest in the night sky, located about 79 light-years from the Sun.
RA: 10h 08m 27.4s DEC +12° 18′ 27″
Leo I is a dwarf spheroidal galaxy (dSph) in Leo at 820,000 light-years. It is part of the Local Group of galaxies as it is a satellite of our Milky Way (properly Galaxy). It was discovered in 1950 by Albert George Wilson on photographic plates from the Palomar Observatory Sky Survey (POSS). The proximity of Regulus (Alfa Leo) and the low light make it very difficult to observe.
Leo I dSph is still the most distant satellite of the Milky Way, practically at the edge of its halo. Color-magnitude diagrams (CMDs) of Leo I reveal several striking features.
There is a well-defined red giant (RGB) branch that is very blue and has a flatter slope than all other dSphs and galactic globular clusters.
Leo I has no obvious horizontal branch; however, it shows a strong clustering of red giants. Leo I's CMD shows ~50 anomalous Cepheid candidates. There are asymptotic giant branch stars above the tip of the RGB, including 15 carbon stars. This is consistent with the presence of a young population of approximately 3 Gyr.
These results suggest that it is the youngest spheroidal dwarf galaxy in the Milky Way [MG Lee et al. (1993) AJ v.106, p.1420]. However, only recently have some ultrafaint dwarf (UFD) galaxies with hints of recent star formation been discovered. This implies that in smaller, fainter systems, star formation has not completely stopped with reionization [Michelle L M Collins et al. 2024]
At the center of Leo I, a dwarf about 100,000 times less massive than the Milky Way, astronomers have discovered a black hole almost as large as the one at the center of the Milky Way. The discovery challenges theories about the formation of supermassive black holes.
Leo I dSph should not be confused with the nearly homonymous Leo-I galactic group of which M96 is part.
With Tair-3S 300mm f/4.5 telephoto array on April 5, 2024 from suburban sky.
Regulus and the dwarf spheroidal galaxy Leo I
Regulus and the dwarf spheroidal galaxy Leo I
Credit: Giuseppe Donatiello
RA 10h 08m 22.311s DEC +11° 58′ 01.95″
Regulus, α Leonis (α Leo), is the brightest star in Leo and one of the brightest in the night sky, located about 79 light-years from the Sun.
RA: 10h 08m 27.4s DEC +12° 18′ 27″
Leo I is a dwarf spheroidal galaxy (dSph) in Leo at 820,000 light-years. It is part of the Local Group of galaxies as it is a satellite of our Milky Way (properly Galaxy). It was discovered in 1950 by Albert George Wilson on photographic plates from the Palomar Observatory Sky Survey (POSS). The proximity of Regulus (Alfa Leo) and the low light make it very difficult to observe.
Leo I dSph is still the most distant satellite of the Milky Way, practically at the edge of its halo. Color-magnitude diagrams (CMDs) of Leo I reveal several striking features.
There is a well-defined red giant (RGB) branch that is very blue and has a flatter slope than all other dSphs and galactic globular clusters.
Leo I has no obvious horizontal branch; however, it shows a strong clustering of red giants. Leo I's CMD shows ~50 anomalous Cepheid candidates. There are asymptotic giant branch stars above the tip of the RGB, including 15 carbon stars. This is consistent with the presence of a young population of approximately 3 Gyr.
These results suggest that it is the youngest spheroidal dwarf galaxy in the Milky Way [MG Lee et al. (1993) AJ v.106, p.1420]. However, only recently have some ultrafaint dwarf (UFD) galaxies with hints of recent star formation been discovered. This implies that in smaller, fainter systems, star formation has not completely stopped with reionization [Michelle L M Collins et al. 2024]
At the center of Leo I, a dwarf about 100,000 times less massive than the Milky Way, astronomers have discovered a black hole almost as large as the one at the center of the Milky Way. The discovery challenges theories about the formation of supermassive black holes.
Leo I dSph should not be confused with the nearly homonymous Leo-I galactic group of which M96 is part.
With Tair-3S 300mm f/4.5 telephoto array on April 5, 2024 from suburban sky.