ESO 291- G 012,IRAS 23134-4251,IC 5294,MCG -07-47-028,PGC 70884,VV 440[1]
NGC 7552 (also known asIC 5294) is abarred spiral galaxy in the constellationGrus. It is at a distance of roughly 60 millionlight 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]
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°.[4] The one arm is more prominent and the less prominent arm shows no clear continuation with the bar. The bar is dusty,[5] and four huge HII regions are detected in it.[6] The disk features numerous scatteredHII regions in an asymmetric pattern.[7] The totalinfrared luminosity of the galaxy is1011.03L☉, and thus is categorised as aluminous infrared galaxy.[8]
TheSIMBAD database lists NGC7552 as aSeyfert I Galaxy, i.e. it has aquasar-like nucleus with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, the host galaxy is clearly detectable.[9]
The starburst ring in mid-infrared by the T-ReCS of Gemini Observatory.
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.[10] The ring is more than 100 parsecs wide.[4]
The ring is brighter north of the nucleus and there is inhabited by the younger star populations.[7] 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⊙.[4] 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 theVery Large Array at 46.9 MHz and theAustralia Telescope Compact Array.[11]
Onesupernova has been observed in NGC 7552:SN 2017bzc (Type Ia, mag. 12.8) was discovered by Stuart Parker as part of theBackyard Observatory Supernova Search (BOSS) on 7 march 2017.[12][13]In addition, aluminous red nova has also been observed in NGC 7552:AT 2014ej (type LRN, mag. 18.0), also known asNGC7552-2014OT1, was discovered by Peter Marples also as part of BOSS on 24 September 2014.[14][15][16]
NGC 7552 belongs in NGC 7582 group, also known as the Grus group. Other members of the group include the spiral galaxiesNGC 7599,NGC 7590, andNGC 7582,[17] 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,[17] yet NGC 7552 does not have highly disturbed morphology.[18]
