Andromeda II

Andromeda II also briefly And II is a spheroidal dwarf galaxy ( dSph ) in the constellation of Andromeda. The galaxy is about 2.22 million light-years away from our solar system. Andromeda II is a member of the Local Group, and is a satellite of the Andromeda Galaxy M31, but is also the Triangulum Galaxy M33 very close, so could both Trabant one or the other parent galaxy to be.

And II was discovered by Sidney van den Bergh in 1970 with photographic plates taken with the 1.2- m Oschin Schmidt telescope at Palomar Observatory in the years 1970 and 1971, together with Andromeda I, Andromeda III and within a screening probable background galaxy Andromeda IV

Properties

Using the Keck telescope could Côté et al. Create 1999 individual spectra of 7 stars within Andromeda II. From these data, an average radial velocity of vr = ( -188 ± 3) km / s and a velocity dispersion of ( 9.2 ± 2.6 ) km / s could be identified. This resulted in a mass-luminosity ratio of M / Lv = 21 compared to the Sun, which represents a significant amount of dark matter. Again in 1999 could Côté, Oke, & Cohen using the Keck telescope spectra of 42 red giants of this dwarf galaxy. This could be an average metallicity of [Fe / H] = -1.47 ± 0.19 and 0.35 ± 0.10 of a Metallizitätsdispersion derived.

Again in 1999 were studies of the color-magnitude diagram of And II by Da Costa et al., That most of the stars had there an age 6-9 billion years ago. Nevertheless, the observations of RR Lyrae stars and blue horizontal branch stars in the existence of a population with an age showed greater than 10 billion years ago.

And II differs from Andromeda I by the absence of a radial gradient in the horizontal branch morphology. The dispersion of the metal abundances is significantly greater here than in And I. This implies a fundamentally different development of these two satellites of the Andromeda nebula. Also, it raises the question of whether a relationship between radial gradient of the horizontal branch and the Metallizitätsdispersion in spheroidal dwarf galaxies exist.

More

  • List of satellite galaxies of Andromeda
  • Andromeda Galaxy
Andromeda (constellation) Declination RR Lyrae variable Digital Object Identifier arXiv Messier 32 Messier 110 NGC 185 NGC 147 Andromeda V Andromeda VIII Andromeda IX Andromeda X Andromeda XI
3130
de