NGC 147
.jpg) Zdjęcie z Kosmicznego Teleskopu Hubble’a | |
| Odkrywca | |
|---|---|
| Data odkrycia | 8 września 1829 |
| Dane obserwacyjne (J2000) | |
| Gwiazdozbiór | |
| Typ | karłowata eliptyczna/sferoidalna |
| Rektascensja | 00h 33m 11,7s |
| Deklinacja | +48° 30′ 26″ |
| Odległość | |
| Przesunięcie ku czerwieni | –0,000644[2] |
| Jasność obserwowana | |
| Rozmiary kątowe | 13,2′ × 7,8′ |
| Charakterystyka fizyczna | |
| Wymiary | ∅ 8,5 tys. ly[3] |
| Jasność absolutna | |
| Masa | |
| Alternatywne oznaczenia | |
| PGC 2004, UGC 326, MCG 8-2-5, DDO 3, ZWG 550.6 | |
NGC 147 (również PGC 2004 lub UGC 326) – karłowata galaktyka eliptyczna lub sferoidalna, znajdująca się w gwiazdozbiorze Kasjopei, oddalona od Ziemi o około 2,2 miliona lat świetlnych. Została odkryta 8 września 1829 roku przez Johna Herschela[4].
Galaktyka NGC 147 należy do Grupy Lokalnej i jest satelitą Galaktyki Andromedy.
Zobacz też
Przypisy
- ↑ a b c d e Alan W. McConnachie. The observed properties of dwarf galaxies in and around the Local Group. „The Astronomical Journal”. 144 (1), s. 4, lipiec 2012. DOI: 10.1088/0004-6256/144/1/4. (ang.).
- ↑ NGC 147 w bazie SIMBAD (ang.)
- ↑ Obliczono ze wzoru gdzie – średnica, – odległość, – rozmiar kątowy obiektu.
- ↑ Courtney Seligman: NGC 147. [w:] Celestial Atlas [on-line]. [dostęp 2014-11-03]. (ang.).
Linki zewnętrzne
- NGC 147 w serwisie SEDS.org (Revised NGC and IC Catalog) (ang.)
- NGC 147 w bazie SIMBAD (ang.)
- NGC 147 w NASA/IPAC Extragalactic Database (ang.)
Media użyte na tej stronie
Autor: NASA Hubble Space Telescope, Licencja: CC BY 2.0
Caldwell 17, also known as NGC 147, is a dwarf galaxy located roughly 2.5 million light-years from Earth. It is a member of the Local Group of galaxies, which is dominated by our Milky Way and the Andromeda galaxy. Caldwell 17, like its neighbor Caldwell 18, is a distant satellite of the Andromeda galaxy. Just as the planets in the solar system are gravitationally bound to the Sun, so are these smaller galaxies bound to their much more massive galactic host. While many classes of galaxies can exist as satellites, dwarf spheroidal galaxies (small, dim, spherical-shaped galaxies) like Caldwell 17 have been observed in this role more frequently than any other type of galaxy.
Dwarf satellite galaxies tend to appear very diffuse and dim, so they can be difficult to spot (especially in light-polluted or hazy skies). Caldwell 17 is no exception. It has an apparent magnitude of 9.5, and observers will need a small telescope set up in a dark location to detect the faint galaxy. Caldwell 17 is located in the southern edge of the constellation Cassiopeia, between the constellation’s “W” pattern and the Andromeda galaxy. (The neighboring Caldwell 18 is brighter and less diffuse, so it is easier to see.) The best time of year to spot Caldwell 17 from the Northern Hemisphere is the autumn. It can also be seen in northern latitudes of the Southern Hemisphere in the spring. The galaxy was discovered by the English astronomer John Herschel in September of 1829.
This image of Caldwell 17 is a composite of observations made in visible and infrared light by Hubble’s Wide Field Camera 3. The image captures an area near the core of the galaxy, which is notable for its elderly stellar population. Astronomers used Hubble’s observations to investigate the properties of Caldwell 17’s many globular star clusters.
Credit: NASA, ESA, and A. Ferguson (University of Edinburgh, Institute for Astronomy); Processing: Gladys Kober (NASA/Catholic University of America)
For Hubble's Caldwell catalog website and information on how to find these objects in the night sky, visit: <a href="https://www.nasa.gov/content/goddard/hubble-s-caldwell-catalog" rel="noreferrer nofollow">www.nasa.gov/content/goddard/hubble-s-caldwell-catalog</a>