Astronomy:NGC 1637

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NGC 1637
NGC 1637 imaged by the Very Large Telescope
Observation data (J2000 epoch)
ConstellationEridanus
Right ascension 04h 41m 28.229s[1]
Declination−02° 51′ 28.94″[1]
Redshift0.00239[2]
Helio radial velocity717.1±1.2 km/s[2]
Distance9.77 ± 1.82 Mpc (31.9 ± 5.9 Mly)[3]
9.18 Mpc (29.9 Mly) h−10.73[4]
Apparent magnitude (V)11.5[5]
Apparent magnitude (B)11.25[6]
Characteristics
TypeSAB(rs)c[3] or SBc(s)II.3[7]
Size~57,000 ly (17.48 kpc) (estimated)[5]
Apparent size (V)4.0′ × 3.2′[5]
Other designations
AGC 440323, IRAS 04389-0257, MCG+00-12-068, PGC 15821[5]

NGC 1637 is an isolated, non-interacting[7] intermediate spiral galaxy in the constellation Eridanus, about a degree to the WNW of the star Mu Eridani.[8] It was discovered by German-British astronomer William Herschel on 1 February 1786.[9][10] It is located at a distance of about 9.77 ± 1.82 Mpc (31.9 ± 5.9 Mly) from the Milky Way.[3] The galaxy is inclined at an angle of 31.1° to the line of sight from the Earth and the long axis is oriented along a position angle of 16.3°.[3]

In 1991, Gérard de Vaucouleurs and associates assigned a morphological classification of SAB(rs)c to NGC 1637, indicating a spiral galaxy with a weak bar structure (SAB) across the nucleus, surrounded by a partial ring (rs) and somewhat loosely-wound arms (c).[7] While the inner section of the galaxy shows a symmetrical two-arm structure,[6] it has a single outer spiral arm that wraps 180° around the nucleus,[6] giving the galaxy an overall asymmetric, lopsided appearance.[7] The outer spiral arm has a red component that indicates a significant age.[6] However, the existence of this structure is difficult to explain.[7] The galaxy shows indications of recent starburst activity that may have terminated around 15 million years ago.[6]

The active central nucleus shows weak LINER behavior, and it may be an intermediate form between a LINER and an H II region.[7] The luminosity of the X-ray source at the nucleus is 1.2×1038 ergs s−1 in the 0.3–7 keV band.[6]

Supernovae

The majority of the image shows a face-on spiral galaxy speckled with myriad blue and red stars. The yellowish core of the galaxy forms a fuzzy oval tilted to the upper right. About halfway from the core to the edge of the image at about 4 o’clock, a small region is outlined with a white box. A shaded, nearly transparent white triangle extends to a pullout at upper right labeled “before explosion”, with short lines forming a crosshair that points to a red star at the center. Below this are three more square images, all with crosshairs at the same location. 1) Hubble August 2024, with nothing visible in the crosshairs, 2) Webb October 2024, with a red star in the crosshairs, 3) Hubble July 2025, with a blue supernova in the crosshairs.
NGC 1637 showing SN 2025pht and its progenitor

Two supernovae have been observed in NGC 1637:

See also

References

  1. ↑ 1.0 1.1 Skrutskie, Michael F.; Cutri, Roc M.; Stiening, Rae; Weinberg, Martin D.; Schneider, Stephen E.; Carpenter, John M.; Beichman, Charles A.; Capps, Richard W. et al. (1 February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal 131 (2): 1163–1183. doi:10.1086/498708. ISSN 0004-6256. Bibcode: 2006AJ....131.1163S. 
  2. ↑ 2.0 2.1 Haynes, Martha P. et al. (January 1998). "Asymmetry in High-Precision Global H i Profiles of Isolated Spiral Galaxies". The Astronomical Journal 115 (1): 62–79. doi:10.1086/300166. Bibcode: 1998AJ....115...62H. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Crowther, Paul A. (January 2013). "On the association between core-collapse supernovae and H ii regions". Monthly Notices of the Royal Astronomical Society 428 (3): 1927–1943. doi:10.1093/mnras/sts145. Bibcode: 2013MNRAS.428.1927C. 
  4. ↑ "NASA/IPAC Extragalactic Database". Results for NGC 1512, Co-Moving Radial Distance. http://nedwww.ipac.caltech.edu/. 
  5. ↑ 5.0 5.1 5.2 5.3 "NASA/IPAC Extragalactic Database". Results for NGC 1637. http://nedwww.ipac.caltech.edu/. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Immler, Stefan et al. (October 2003). "A Deep Chandra X-Ray Observation of NGC 1637". The Astrophysical Journal 595 (2): 727–742. doi:10.1086/377474. Bibcode: 2003ApJ...595..727I. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 Sohn, Young-Jong; Davidge, T. J. (January 1998). "VRI CCD Photometry of Supergiant Stars in the Barred Galaxies NGC 925 and NGC 1637". The Astronomical Journal 115 (1): 130–143. doi:10.1086/300163. Bibcode: 1998AJ....115..130S. 
  8. ↑ Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. 1. Sky Publishing Corporation and the European Space Agency. ISBN 0-933346-84-0. 
  9. ↑ Herschel, W. (1789). "Catalogue of a Second Thousand of New Nebulae and Clusters of Stars; with a Few Introductory Remarks on the Construction of the Heavens". Philosophical Transactions of the Royal Society of London 79: 212–255. doi:10.1098/rstl.1789.0021. Bibcode: 1789RSPT...79..212H. 
  10. ↑ Seligman, Courtney. "New General Catalogue Objects: NGC 1637". https://cseligman.com/text/atlas/ngc16.htm#1637. 
  11. ↑ Li, W. D. (1999). "Supernova 1999em in NGC 1637". International Astronomical Union Circular (7294): 1. Bibcode: 1999IAUC.7294....1L. 
  12. ↑ "SN 1999em". IAU. https://www.wis-tns.org/object/1999em. 
  13. ↑ Bishop, David. "Bright Supernovae - 1999 : SN 1999em". Astronomy Section, Rochdale Academy of Science. https://www.rochesterastronomy.org/snimages/sn1999/#1999em. 
  14. ↑ "SN 2025pht". IAU. https://www.wis-tns.org/object/2025pht. 
  15. ↑ Kilpatrick, Charles D.; Suresh, Aswin; Davis, Kyle W.; Drout, Maria R.; Foley, Ryan J.; Gagliano, Alexander; Jacobson-Galán, Wynn V.; Kaur, Ravjit et al. (2025). "The Type II SN 2025pht in NGC 1637: A Red Supergiant with Carbon-rich Circumstellar Dust as the First JWST Detection of a Supernova Progenitor Star". The Astrophysical Journal 992 (1): L10. doi:10.3847/2041-8213/ae04de. Bibcode: 2025ApJ...992L..10K. 



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