U Equulei

U Equulei

A visual band light curve for U Equulei, plotted from OMC data
Observation data
Epoch J2000      Equinox ICRS
Constellation Equuleus
Right ascension 20h 57m 16.28s
Declination +02° 58′ 44.6″
Apparent magnitude (V) 9 - 13
Characteristics
Evolutionary stage (post?) AGB
Spectral type G - K III
B−V color index +1.6
Variable type Lb
Astrometry
Radial velocity (Rv)−75 km/s
Proper motion (μ) RA: 10.490 mas/yr
Dec.: −10.433 mas/yr
Parallax (π)0.0985±0.0750 mas
Distance3,340±700 pc
Details
Luminosity6,000 L☉
Temperature5,005 K
Other designations
IRAS 20547+0247, 2MASS J20571628+0258445, Gaia DR2 1731164844433296128
Database references
SIMBADdata

U Equulei (U Equ / IRAS 20547+0247) is a variable star in the constellation Equuleus with an apparent magnitude of +14.50 in the B band. It lies at an estimated distance of 5,000 light-years (1,500 parsecs) from the Solar System.

Properties

U Equulei is, or was, an OH/IR star, and strong OH and H2O masers have been observed. These vary to a greater extent than almost any other star observed, and it is possible that the stage of maser activity is essentially finished.

Hypothetical planet

Lionel Siess and Mario Livio suggested that the accretion of a giant planet towards the increasing red giant has made the star's outer layers rotate fast enough to cause an outpouring equatorial- or disk-expansion, responsible for the star's peculiar environment. The spectroscopic study has indicated the star is surrounded by the dust shell, but shape of the shell cannot be measured due to large distance to the star.

See also

References

  1. ↑ "OMC Archive". OMC Archive. The Astronomical Data Centre at CAB. Retrieved 19 December 2021.
  2. 1 2 Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  3. 1 2 Geballe, T.R.; Barnbaum, C.; Noll, Keith S.; Morris, M. (September 2012). "Infrared Spectroscopy of U Equulei's Warm Circumstellar Gas". The Astrophysical Journal. 624 (2): 983–984. arXiv:astro-ph/0502154. Bibcode:2005ApJ...624..983G. doi:10.1086/429369. S2CID 14707061.
  4. 1 2 3 Barnbaum, C.; Omont, A.; Morris, M. (1996). "The unusual circumstellar environment of the evolved star, U Equulei". Astronomy and Astrophysics. 310: 259. Bibcode:1996A&A...310..259B.
  5. ↑ Kim, Jaeheon; Cho, Se-Hyung; Kim, Sang Joon (2013). "Simultaneous Observations of SiO and H2O Masers toward Known Stellar H2O Maser Sources". The Astronomical Journal. 145 (1): 22. Bibcode:2013AJ....145...22K. doi:10.1088/0004-6256/145/1/22. S2CID 121415544.
  6. 1 2 3 4 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  7. 1 2 Vickers, Shane B.; Frew, David J.; Parker, Quentin A.; Bojičić, Ivan S. (2015). "New light on Galactic post-asymptotic giant branch stars – I. First distance catalogue". Monthly Notices of the Royal Astronomical Society. 447 (2): 1673–1691. arXiv:1403.7230. Bibcode:2015MNRAS.447.1673V. doi:10.1093/mnras/stu2383. S2CID 119245776.
  8. ↑ Lewis, B. M. (2002). "On Dead OH/IR Stars". The Astrophysical Journal. 576 (1): 445–449. Bibcode:2002ApJ...576..445L. doi:10.1086/341534. S2CID 121803017.
  9. ↑ Siess, Lionel; Mario Livio (October 1999). "The accretion of brown dwarfs and planets by giant stars – II. Solar-mass stars on the red giant branch". Monthly Notices of the Royal Astronomical Society. 308 (4): 1133–1149. arXiv:astro-ph/9905235. Bibcode:1999MNRAS.308.1133S. doi:10.1046/j.1365-8711.1999.02784.x. S2CID 12893455.
  10. ↑ Yung, Bosco H. K.; Nakashima, Jun-Ichi; Hsia, Chih-Hao; Imai, Hiroshi (2016). "Do Water Fountain Jets Really Indicate the Onset of the Morphological Metamorphosis of Circumstellar Envelopes". Monthly Notices of the Royal Astronomical Society. 465 (4): 4482–4499. arXiv:1611.03306. doi:10.1093/mnras/stw2931. S2CID 119058467.