U Equulei

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U Equulei
UEquLightCurve.png
A visual band light curve for U Equulei, plotted from OMC data [1]
Observation data
Epoch J2000       Equinox J2000
Constellation Equuleus
Right ascension 20h 57m 16.28s [2]
Declination +02° 58′ 44.6″ [2]
Apparent magnitude  (V)9 - 13 [3]
Characteristics
Evolutionary stage (post?) AGB [4]
Spectral type G - K III [4]
B−V color index +1.6 [4]
Variable type Lb [3]
Astrometry
Radial velocity (Rv)−75 [5] km/s
Proper motion (μ)RA: 10.490 [6] mas/yr
Dec.: −10.433 [6] mas/yr
Parallax (π)0.0985±0.0750  mas [6]
Distance 3,340±700 [7]   pc
Details
Luminosity 6,000 [7]   L☉
Temperature 5,005 [6]   K
Other designations
IRAS  20547+0247, 2MASS  J20571628+0258445, Gaia DR2 1731164844433296128
Database references
SIMBAD data

U Equulei (U Equ / IRAS 20547+0247) is a variable star in the Equuleus constellation 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.

Contents

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. [8]

Theoretical 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. [9] 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. [10]

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.
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