NGC 7552 explained

NGC 7552
Credit:NASA/STScI/WikiSky
Epoch:J2000
Type:(R')SB(s)ab [1]
Dist Ly:56 Mly (17.2 Mpc)
H Radial V:1608 ± 5 km/s
Appmag V:11.2
Size V:3.4 × 2.7
Constellation Name:Grus

NGC 7552 (also known as IC 5294) is a barred spiral galaxy in the constellation Grus. It is at a distance of roughly 60 million light years from Earth, which, given its apparent dimensions, means that NGC 7552 is about 75,000 light years across. It forms with three other spiral galaxies the Grus Quartet.[2]

Observation history

NGC 7552 was originally discovered and reported in 1826 by James Dunlop and John Herschel added it in the General Catalogue of Nebulae and Clusters as number 3977. However, Lewis Swift reported the galaxy independently in on October 22, 1897, at right ascention 9 arcseconds off the location of the galaxy and was included in Index Catalogue as IC 5294.[3]

Structure

NGC 7552 is a barred spiral galaxy, with two spiral arms forming an outer pseudo-ring. The galaxy is seen nearly face on, at an inclination of ~ 28°. The one arm is more prominent and the less prominent arm shows no clear continuation with the bar. The bar is dusty,[4] and four huge HII regions are detected in it.[5] The disk features numerous scattered HII regions in an asymmetric pattern.[6] The total infrared luminosity of the galaxy is, and thus is categorised as a luminous infrared galaxy.[7]

Starburst ring

In 1994, Forbes et al. observed a partial starburst ring with 1 kpc radius at Br-gamma with various hot spots. They also detected a small-scale molecular bar and a large reservoir of molecular material, however, no evidence of current activity was detected at the nucleus.[8] The ring is more than 100 parsecs wide.

The ring is brighter north of the nucleus and there is inhabited by the younger star populations.[6] Brandl et al. detected in near- and mid-infrared nine prominent structures within the ring they identified as star clusters with stellar ages ranging between 5.5 Myr and 6.3 Myr. These clusters account for the 75% of the bolometric luminosity of the starburst ring, with total luminosity of the clusters 2.1 × 1010 L⊙.[9] Numerous supernova remnants have been observed in the ring. Further observations of the galaxy in radio waves showed that NGC 7552 contains three star forming rings of radii 1.0 kpc, 1.9 kpc, and 3.4 kpc as observed by the Very Large Array at 46.9 MHz and the Australia Telescope Compact Array.[10]

One supernova has been observed in NGC 7552: SN 2017bzc (Type Ia, mag. 12.8).[11]

Galaxy group

NGC 7552 belongs in NGC 7582 group, also known as the Grus group. Other members of the group include the spiral galaxies NGC 7599, NGC 7590, and NGC 7582,[12] which along with NGC 7552 form the Grus Quartet. A large tidal extension of HI reaches from NGC 7582 to NGC 7552, which is indicative of interactions between the group members,[12] yet NGC 7552 does not have highly disturbed morphology.[13]

See also

Notes and References

  1. Web site: NASA/IPAC Extragalactic Database . Results for NGC 7552 . 2016-01-18 .
  2. Book: Bakich, Michael E.. 1,001 Celestial Wonders to See Before You Die. limited. 2010. Springer Science+Business Media, LLC. New York, New York. 978-1-4419-1777-5. 334. 2010ocws.book.....B.
  3. Book: O'Meara. Stephen James. Southern gems. 2013. Cambridge University Press. Cambridge. 978-1107015012. 421–422. Meara.
  4. Laurikainen. Eija. Salo. Heikki. Buta. Ronald. Vasylyev. Sergiy. Bar-induced perturbation strengths of the galaxies in the Ohio State University Bright Galaxy Survey - I. Monthly Notices of the Royal Astronomical Society. December 2004. 355. 4. 1251–1271. 10.1111/j.1365-2966.2004.08410.x. free . astro-ph/0409503. 2004MNRAS.355.1251L. 17172976.
  5. Feinstein. C.. Mendez. M.. Vega. I.. Forte. J. C.. A CCD morphological study of the starburst galaxy NGC 7552. Astronomy and Astrophysics. November 1990. 239. 1–2. 90–96. 12 March 2017. 1990A&A...239...90F.
  6. Seidel. M. K.. Cacho. R.. Ruiz-Lara. T.. Falcon-Barroso. J.. Perez. I.. Sanchez-Blazquez. P.. Vogt. F. P. A.. Ness. M.. Freeman. K.. Aniyan. S.. Dissecting galactic bulges in space and time - I. The importance of early formation scenarios versus secular evolution. Monthly Notices of the Royal Astronomical Society. 30 November 2014. 446. 3. 2837–2860. 10.1093/mnras/stu2295. free . 1411.2969. 2015MNRAS.446.2837S. 118459544.
  7. Sanders . D. B. . Mazzarella . J. M. . Kim . D.-C. . Surace . J. A. . Soifer . B. T. . The IRAS Revised Bright Galaxy Sample . The Astronomical Journal . October 2003 . 126 . 4 . 1607–1664 . 10.1086/376841. 2003AJ....126.1607S . astro-ph/0306263 . 14825701 .
  8. Forbes. Duncan A.. Kotilainen. Jari K.. Moorwood. A. F. M.. NGC 7552: A galaxy with a dormant active nucleus?. The Astrophysical Journal. September 1994. 433. L13. 10.1086/187536. 1994ApJ...433L..13F. free.
  9. Brandl. B. R.. Martín-Hernández. N. L.. Schaerer. D.. Rosenberg. M.. van der Werf. P. P.. High resolution IR observations of the starburst ring in NGC 7552. Astronomy & Astrophysics. 27 June 2012. 543. A61. 10.1051/0004-6361/201117568. 1205.1922. 2012A&A...543A..61B. 118999106.
  10. Roy. A. L.. Goss. W. M.. Anantharamaiah. K. R.. Detection of the H92α recombination line from the starbursts in the Circinus galaxy and NGC 1808. Astronomy and Astrophysics. May 2008. 483. 1. 79–88. 10.1051/0004-6361:20077405. 0802.3175. 2008A&A...483...79R. 16564405.
  11. https://www.wis-tns.org/object/2017bzc Transient Name Server entry for SN 2017bzc.
  12. Freeland. E.. Stilp. A.. Wilcots. E.. H I Observations of Five Groups of Galaxies. The Astronomical Journal. 1 July 2009. 138. 1. 295–304. 10.1088/0004-6256/138/1/295. 0905.3907. 2009AJ....138..295F. 15714969.
  13. Wood. Corey M.. Tremonti. Christy A.. Calzetti. Daniela. Daniela Calzetti . Leitherer. Claus. Chisholm. John. Gallagher. John S.. Supernova-driven outflows in NGC 7552: a comparison of H α and UV tracers. Monthly Notices of the Royal Astronomical Society. 25 July 2015. 452. 3. 2712–2730. 10.1093/mnras/stv1471. free . 1507.00346. 2015MNRAS.452.2712W. 118422451.

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