NGC 973
{{Short description|Galaxy in the constellation Triangulum}}
{{Infobox galaxy
| name = NGC 973
| image = NGC 973 PanSTARRS1 i.r.g.jpg
| image_size = 250px
| caption = NGC 973 by Pan-STARRS
| credit =
| epoch = J2000
| type = Sbc {{cite web
| title=NASA/IPAC Extragalactic Database
| work=Results for NGC 973
| url=http://ned.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+973
| access-date=2019-01-18 }}
| dist_ly = 195 ± 16 Mly (60.0 ± 4.8 Mpc)
| appmag_v = 12.8 {{cite web |title=Revised NGC Data for NGC 973 |url=http://spider.seds.org/ngc/revngcic.cgi?NGC973 |website=spider.seds.org |access-date=25 November 2018}}
| size_v = 4.03{{prime}} × 0.47{{prime}}
| constellation name = Triangulum
| notes = Seyfert galaxy
| names = UGC 2048, CGCG 505-014, MCG +05-07-013, PGC 9795
}}
NGC 973 is a giant{{cite journal |last1=Saburova |first1=A. S. |title=What made discy galaxies giant? |journal=Monthly Notices of the Royal Astronomical Society |date=January 2018 |volume=473 |issue=3 |pages=3796–3809 |doi=10.1093/mnras/stx2583|doi-access=free |arxiv=1710.01341 |bibcode=2018MNRAS.473.3796S |s2cid=119425646 }} spiral galaxy located in the constellation Triangulum. It is located at a distance of circa 200 million light-years from Earth, which, given its apparent dimensions, means that NGC 973 is about 230,000 light years across. It was discovered by Lewis Swift on October 30, 1885.{{cite web |last1=Seligman |first1=Courtney |title=NGC 973 (= PGC 9795) |url=https://cseligman.com/text/atlas/ngc9a.htm#973 |website=Celestial Atlas |access-date=19 November 2018}}
Characteristics
NGC 973 is seen edge-on, with an inclination of nearly 90°.{{cite journal |last1=Xilouris |first1=E. M. |last2=Kylafis |first2=N. D. |last3=Papamastorakis |first3=J. |last4=Paleologou |first4=E. V. |last5=Haerendel |first5=G. |title=The distribution of stars and dust in spiral galaxies: the edge-on spiral UGC 2048. |journal=Astronomy and Astrophysics |date=1 September 1997 |volume=325 |pages=135–143 |issn=0004-6361 |bibcode=1997A&A...325..135X}} Its bulge is shaped like a box or peanut. The subtraction of axisymmetric components from the profile of the galaxy showed that its bulge has an X-like morphology, which indicates the presence of a bar.{{cite journal |last1=Patsis |first1=P. A. |last2=Xilouris |first2=E. M. |title=Boxy/peanut 'bulges': comparing the structure of galaxies with the underlying families of periodic orbits |journal=Monthly Notices of the Royal Astronomical Society |date=11 March 2006 |volume=366 |issue=4 |pages=1121–1125 |doi=10.1111/j.1365-2966.2005.09922.x|doi-access=free |arxiv=astro-ph/0512244 |bibcode=2006MNRAS.366.1121P |s2cid=15496972 }} A prominent dust lane runs across the galaxy.{{cite journal |last1=Guthrie |first1=B. N. G. |title=Axial ratios of edge-on spirals |journal=Astronomy and Astrophysics Supplement Series |date=1 May 1992 |volume=93 |pages=255–270 |issn=0365-0138 |bibcode=1992A&AS...93..255G}}
The galaxy kinematics revealed that the northeast side is the approaching one and the southwest is receding. The disk appears flat, without warps. The total hydrogen mass of the galaxy is estimated to be about {{val|9|e=9|ul=M_solar}},{{cite journal |last1=Allaert |first1=F. |last2=Gentile |first2=G. |last3=Baes |first3=M. |last4=De Geyter |first4=G. |last5=Hughes |first5=T. M. |last6=Lewis |first6=F. |last7=Bianchi |first7=S. |last8=De Looze |first8=I. |last9=Fritz |first9=J. |last10=Holwerda |first10=B. W. |last11=Verstappen |first11=J. |last12=Viaene |first12=S. |title=HERschel Observations of Edge-on Spirals (HEROES) II. Tilted-ring modelling of the atomic gas disks |journal=Astronomy & Astrophysics |date=30 September 2015 |volume=582 |pages=A18 |doi=10.1051/0004-6361/201526667|arxiv=1507.03095 |bibcode=2015A&A...582A..18A |doi-access=free }} and the total dust mass is estimated to be {{val|1.4|e=8|u=M_solar}}, with clumpy distribution. Faint emission from gas lying outside the plane of the galaxy was detected in H-alpha, correlated with the galactic disk and halo.{{cite journal |last1=Miller |first1=Scott T. |last2=Veilleux |first2=Sylvain |title=Extraplanar Emission-Line Gas in Edge-On Spiral Galaxies. I. Deep Emission-Line Imaging |journal=The Astrophysical Journal Supplement Series |date=October 2003 |volume=148 |issue=2 |pages=383–417 |doi=10.1086/376604|arxiv=astro-ph/0305026 |bibcode=2003ApJS..148..383M |s2cid=15897329 |url=https://cds.cern.ch/record/615057 }}
The nucleus of NGC 973 appears to be active based on its emission. It is categorised as a type 2 Seyfert galaxy.{{cite journal |last1=Hiroi |first1=Kazuo |last2=Ueda |first2=Yoshihiro |last3=Hayashida |first3=Masaaki |last4=Shidatsu |first4=Megumi |last5=Sato |first5=Ryosuke |last6=Kawamuro |first6=Taiki |last7=Sugizaki |first7=Mutsumi |last8=Nakahira |first8=Satoshi |last9=Serino |first9=Motoko |last10=Kawai |first10=Nobuyuki |last11=Matsuoka |first11=Masaru |last12=Mihara |first12=Tatehiro |last13=Morii |first13=Mikio |last14=Nakajima |first14=Motoki |last15=Negoro |first15=Hitoshi |last16=Sakamoto |first16=Takanori |last17=Tomida |first17=Hiroshi |last18=Tsuboi |first18=Yohko |last19=Tsunemi |first19=Hiroshi |last20=Ueno |first20=Shiro |last21=Yamaoka |first21=Kazutaka |last22=Yoshida |first22=Atsumasa |last23=Asada |first23=Masato |last24=Eguchi |first24=Satoshi |last25=Hanayama |first25=Takanori |last26=Higa |first26=Masaya |last27=Ishikawa |first27=Kazuto |last28=Ishikawa |first28=Masaki |last29=Isobe |first29=Naoki |last30=Kohama |first30=Mitsuhiro |last31=Kimura |first31=Masashi |last32=Morihana |first32=Kumiko |last33=Nakagawa |first33=Yujin E. |last34=Nakano |first34=Yuki |last35=Nishimura |first35=Yasunori |last36=Ogawa |first36=Yuji |last37=Sasaki |first37=Masayuki |last38=Sugimoto |first38=Juri |last39=Takagi |first39=Toshihiro |last40=Usui |first40=Ryuichi |last41=Yamamoto |first41=Takayuki |last42=Yamauchi |first42=Makoto |last43=Yoshidome |first43=Koshiro |title=The 37 Month MAXI/GSC Source Catalog of the High Galactic-Latitude Sky |journal=The Astrophysical Journal Supplement Series |date=1 August 2013 |volume=207 |issue=2 |pages=36 | display-authors = 2 |doi=10.1088/0067-0049/207/2/36|arxiv=1307.2455 |bibcode=2013ApJS..207...36H |s2cid=119307506 }}{{cite journal |last1=Verstappen |first1=J. |last2=Fritz |first2=J. |last3=Baes |first3=M. |last4=Smith |first4=M. W. L. |last5=Allaert |first5=F. |last6=Bianchi |first6=S. |last7=Blommaert |first7=J. A. D. L. |last8=De Geyter |first8=G. |last9=De Looze |first9=I. |last10=Gentile |first10=G. |last11=Gordon |first11=K. D. |last12=Holwerda |first12=B. W. |last13=Viaene |first13=S. |last14=Xilouris |first14=E. M. |title=HERschel Observations of Edge-on Spirals (HEROES) I. Far-infrared morphology and dust mass determination |journal=Astronomy & Astrophysics |date=24 July 2013 |volume=556 |pages=A54 |doi=10.1051/0004-6361/201220733|arxiv=1305.3130 |bibcode=2013A&A...556A..54V |doi-access=free }} The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole.
Nearby galaxies
NGC 973 is the largest galaxy in a galaxy group known as the NGC 973 group.{{cite journal |last1=Garcia, A. M. |title=General study of group membership. II - Determination of nearby groups |journal=Astronomy and Astrophysics Supplement Series |date=1993 |volume=100 |issue=1 |pages=47–90 |url=http://cdsarc.u-strasbg.fr/ftp/J/A+AS/100/47/table2.dat |issn=0365-0138 |bibcode=1993A&AS..100...47G}} The NGC 973 group is one of the largest galaxy groups of the Perseus–Pisces Supercluster,{{cite web |title=The Perseus-Pisces Supercluster |url=http://www.atlasoftheuniverse.com/superc/perpsc.html |website=www.atlasoftheuniverse.com}} with at least 39 galaxies identified as its members. Other members of the group include NGC 917, NGC 931, NGC 940, NGC 969, NGC 974, NGC 978, NGC 987, NGC 983, NGC 1060, NGC 1066, NGC 1067, and UGC 2105.{{cite journal |last1=Crook |first1=Aidan C. |last2=Huchra |first2=John P. |last3=Martimbeau |first3=Nathalie |last4=Masters |first4=Karen L. |last5=Jarrett |first5=Tom |last6=Macri |first6=Lucas M. |title=Erratum: "Groups of Galaxies in the Two Micron All Sky Redshift Survey" (ApJ, 655, 790 [2007]) |journal=The Astrophysical Journal |date=October 2008 |volume=685 |issue=2 |pages=1320–1323 |doi=10.1086/590385|bibcode=2008ApJ...685.1320C |doi-access=free }}
NGC 973 forms a pair with IC 1815, which lies 4.6 arcminutes to the south.Nilson, P. (1973) Uppsala General Catalogue of Galaxies, Acta Universitatis Upsalienis, Nova Regiae Societatis Upsaliensis, Series V: A Vol. 1 A small satellite was discovered in HI imaging near the northeast edge of the disk of NGC 973, with no optical counterpart.
References
{{reflist}}
External links
- {{commonscat-inline}}
- {{WikiSky}}
- [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=NGC%20973 NGC 973 on SIMBAD]
{{Stars of Triangulum}}
{{Ngc10}}
{{Catalogs|NGC=973|PGC=9795|UGC=2048}}
{{DEFAULTSORT:NGC 973}}