NGC 147 (also known as DDO3 or Caldwell 17) is a dwarf spheroidal galaxy about 2.58 Mly away in the constellationCassiopeia. NGC 147 is a member of the Local group of galaxies and a satellite galaxy of the Andromeda Galaxy (M31). It forms a physical pair with the nearby galaxy NGC 185,[5] another remote satellite of M31. It was discovered by John Herschel in September 1829. Visually it is both fainter and slightly larger than NGC 185 (and therefore has a considerably lower surface brightness). This means that NGC 147 is more difficult to see than NGC 185, which is visible in small telescopes. In the Webb Society Deep-Sky Observer's Handbook,[6] the visual appearance of NGC 147 is described as follows:
Large, quite faint, irregularly round; it brightens in the middle to a stellar nucleus.
The membership of NGC 147 in the Local Group was confirmed by Walter Baade in 1944 when he was able to resolve the galaxy into individual stars with the 100-inch (2.5 m) telescope at Mount Wilson near Los Angeles.
A survey of the brightest asymptotic giant branch (AGB) stars in the area of radius 2′ from the center of NGC 147 shows that the last significant star-forming activity in NGC 147 occurred around 3 Gyr ago.[7] NGC 147 contains a large population of older stars which show a spread in metallicity and age. The metallicity spread suggests that NGC 147 has had chemical enrichment. However, H I has not been observed and the interstellar medium (ISM) mass upper limit is much lower than expected had the material which is emitted from evolving stars been kept in the galaxy. This implies depletion of the ISM.[7]
Distance measurements
At least two techniques have been used to measure distances to NGC 147. The surface brightness fluctuations distance measurement technique estimates distances to spiral galaxies based on the graininess of the appearance of their bulges. The distance measured to NGC 147 using this technique is 2.67 ± 0.18 Mly (870 ± 60 kpc).[2] However, NGC 147 is close enough that the tip of the red giant branch (TRGB) method may be used to estimate its distance. The estimated distance to NGC 147 using this technique is 2.21 ± 0.09 Mly (680 ± 30 kpc).[3] Averaged together, these distance measurements give a distance estimate of 2.53 ± 0.11 Mly (780 ± 30 kpc).[a]
^ abcdefghi"NASA/IPAC Extragalactic Database". Results for NGC 147. Retrieved 2006-12-07.
^ abJ. L. Tonry; A. Dressler; J. P. Blakeslee; E. A. Ajhar; et al. (2001). "The SBF Survey of Galaxy Distances. IV. SBF Magnitudes, Colors, and Distances". Astrophysical Journal. 546 (2): 681–693. arXiv:astro-ph/0011223. Bibcode:2001ApJ...546..681T. doi:10.1086/318301. S2CID 17628238.
^ abMcConnachie, A. W.; Irwin, M. J.; Ferguson, A. M. N.; Ibata, R. A.; et al. (2005). "Distances and metallicities for 17 Local Group galaxies". Monthly Notices of the Royal Astronomical Society. 356 (4): 979–997. arXiv:astro-ph/0410489. Bibcode:2005MNRAS.356..979M. doi:10.1111/j.1365-2966.2004.08514.x.
^Karachentsev, I. D.; Kashibadze, O. G. (2006). "Masses of the local group and of the M81 group estimated from distortions in the local velocity field". Astrophysics. 49 (1): 3–18. Bibcode:2006Ap.....49....3K. doi:10.1007/s10511-006-0002-6. S2CID 120973010.
^Jones, K. G. (1981). Webb Society Deep-Sky Observer's Handbook. Enslow Publishers. ISBN978-0-89490-134-8.
^ abDavidge, T. J. (2005). "The Evolved Stellar Content of NGC 147, NGC 185, and NGC 205". The Astronomical Journal. 130 (5): 2087–2103. arXiv:astro-ph/0509612. Bibcode:2005AJ....130.2087D. doi:10.1086/491706. S2CID 17456987.
External links
Wikimedia Commons has media related to NGC 147.
NGC 147 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
April 30, 2023
also, known, ddo3, caldwell, dwarf, spheroidal, galaxy, about, away, constellation, cassiopeia, member, local, group, galaxies, satellite, galaxy, andromeda, galaxy, forms, physical, pair, with, nearby, galaxy, another, remote, satellite, discovered, john, her. NGC 147 also known as DDO3 or Caldwell 17 is a dwarf spheroidal galaxy about 2 58 Mly away in the constellation Cassiopeia NGC 147 is a member of the Local group of galaxies and a satellite galaxy of the Andromeda Galaxy M31 It forms a physical pair with the nearby galaxy NGC 185 5 another remote satellite of M31 It was discovered by John Herschel in September 1829 Visually it is both fainter and slightly larger than NGC 185 and therefore has a considerably lower surface brightness This means that NGC 147 is more difficult to see than NGC 185 which is visible in small telescopes In the Webb Society Deep Sky Observer s Handbook 6 the visual appearance of NGC 147 is described as follows NGC 1472MASS image of NGC 147Observation data J2000 epoch ConstellationCassiopeiaRight ascension00h 33m 12 1s 1 Declination 48 30 32 1 Redshift 193 3 km s 1 Distance2 53 0 11 Mly 780 30 kpc 2 3 4 a Apparent magnitude V 10 5 1 CharacteristicsTypedSph dE5 1 Apparent size V 13 2 7 8 1 Notable featuressatellite galaxy of M31Other designationsPGC 2004 1 UGC 326 1 DDO 3 1 LEDA 2004 Caldwell 17 Large quite faint irregularly round it brightens in the middle to a stellar nucleus The membership of NGC 147 in the Local Group was confirmed by Walter Baade in 1944 when he was able to resolve the galaxy into individual stars with the 100 inch 2 5 m telescope at Mount Wilson near Los Angeles Contents 1 Characteristics 2 Distance measurements 3 See also 4 Notes 5 References 6 External linksCharacteristics EditA survey of the brightest asymptotic giant branch AGB stars in the area of radius 2 from the center of NGC 147 shows that the last significant star forming activity in NGC 147 occurred around 3 Gyr ago 7 NGC 147 contains a large population of older stars which show a spread in metallicity and age The metallicity spread suggests that NGC 147 has had chemical enrichment However H I has not been observed and the interstellar medium ISM mass upper limit is much lower than expected had the material which is emitted from evolving stars been kept in the galaxy This implies depletion of the ISM 7 Distance measurements EditAt least two techniques have been used to measure distances to NGC 147 The surface brightness fluctuations distance measurement technique estimates distances to spiral galaxies based on the graininess of the appearance of their bulges The distance measured to NGC 147 using this technique is 2 67 0 18 Mly 870 60 kpc 2 However NGC 147 is close enough that the tip of the red giant branch TRGB method may be used to estimate its distance The estimated distance to NGC 147 using this technique is 2 21 0 09 Mly 680 30 kpc 3 Averaged together these distance measurements give a distance estimate of 2 53 0 11 Mly 780 30 kpc a See also EditAndromeda s satellite galaxiesNotes Edit average 870 60 680 30 870 680 2 602 302 0 5 2 780 30References Edit a b c d e f g h i NASA IPAC Extragalactic Database Results for NGC 147 Retrieved 2006 12 07 a b J L Tonry A Dressler J P Blakeslee E A Ajhar et al 2001 The SBF Survey of Galaxy Distances IV SBF Magnitudes Colors and Distances Astrophysical Journal 546 2 681 693 arXiv astro ph 0011223 Bibcode 2001ApJ 546 681T doi 10 1086 318301 S2CID 17628238 a b McConnachie A W Irwin M J Ferguson A M N Ibata R A et al 2005 Distances and metallicities for 17 Local Group galaxies Monthly Notices of the Royal Astronomical Society 356 4 979 997 arXiv astro ph 0410489 Bibcode 2005MNRAS 356 979M doi 10 1111 j 1365 2966 2004 08514 x Karachentsev I D Kashibadze O G 2006 Masses of the local group and of the M81 group estimated from distortions in the local velocity field Astrophysics 49 1 3 18 Bibcode 2006Ap 49 3K doi 10 1007 s10511 006 0002 6 S2CID 120973010 NGC 147 SIMBAD Centre de donnees astronomiques de Strasbourg Retrieved 2006 12 07 Jones K G 1981 Webb Society Deep Sky Observer s Handbook Enslow Publishers ISBN 978 0 89490 134 8 a b Davidge T J 2005 The Evolved Stellar Content of NGC 147 NGC 185 and NGC 205 The Astronomical Journal 130 5 2087 2103 arXiv astro ph 0509612 Bibcode 2005AJ 130 2087D doi 10 1086 491706 S2CID 17456987 External links Edit Wikimedia Commons has media related to NGC 147 SEDS NGC 147 NGC 147 on WikiSky DSS2 SDSS GALEX IRAS Hydrogen a X Ray Astrophoto Sky Map Articles and images Retrieved from https en wikipedia org w index php title NGC 147 amp oldid 1095081283, wikipedia, wiki, book, books, library,
