IC 1613 (object 1613 in the Index Catalogues (IC), also known as Caldwell 51) is an irregular dwarf galaxy, visible in the constellation Cetus near the star 26 Ceti.[6] It was discovered in 1906 by Max Wolf,[7] and is approaching Earth at 234 km/s.
IC 1613 is a member of the Local Group.[8] It has played an important role in the calibration of the Cepheid variable period-luminosity relation for estimating distances.[9] Other than the Magellanic Clouds, it is one of the few Local Group dwarf irregular galaxy where RR Lyrae-type variables have been observed; this factor, along with an unusually low abundance of interstellar dust both within IC 1613 and along the line of sight enable especially accurate distance estimates.[8][10]
In 1999, Cole et al.[8] used the Hubble Space Telescope to find that the dominant population of this galaxy has an age of ~7 Gyr. Using its Hess diagram, they found that its evolutionary history may be similar to that of the Pegasus Dwarf Irregular Galaxy. Both galaxies are classified as Ir V in the DDO system. Also in 1999, Antonello et al. found five cepheids of Population II in IC 1613, giving self-evident support for the existence of a very old stellar population component of IC 1613. In 1999, King, Modjaz, & Li discovered the first nova ever detected in IC 1613.[11]
IC 1613 contains a WO star known as DR1, which might be the only Wolf–Rayet star in the galaxy,[12][13] although a candidate WC+O binary, SPIRITS14bqe, has been found.[14] The galaxy also contains a Luminous Blue Variable candidate,[15] and a rich population of OB-type[16] stars and OB associations.[17]
There are many faint galaxies close to IC 1613, 14 of which are catalogued as members of a yet-unnamed galaxy cluster located at z≈0.20.[18]
{{cite journal}}
Lokasi Pengunjung: 18.217.80.111