LS IV-14 116

LS IV-14 116[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Aquarius
Right ascension +20h 57m 38.875s[2]
Declination −14° 25′ 44.01″[2]
Apparent magnitude (V) +12.93[3]
Characteristics
Spectral type sdB0.5VIIHe18[4]
B−V color index −0.16[3]
Variable type sdBVr[5][6]
Details
Surface gravity (log g)5.94 ± 0.04[7] cgs
Temperature34,950 ± 250[7] K
Other designations
2MASS J20573887-1425437, UCAC4 378-169675, V366 Aquarii
Database references
SIMBADdata

LS IV-14 116 is a hot subdwarf located approximately 2,000 light years away on the border between the constellations Capricornus and Aquarius. It has a surface temperature of approximately 34,000 ± 500 kelvins.[8] Along with stars HE 2359-2844 and HE 1256-2738, LS IV-14 116 forms a new group of star called heavy metal subdwarfs. These are thought to be stars contracting to the extended horizontal branch after a helium flash and ejection of their atmospheres at the tip of the red giant branch.[9]

A light curve for V366 Aquarii, adapted from Jeffery (2011)[10]

Amir Ahmad and C. Simon Jeffery discovered that the star is a variable star, in 2004, and published their discovery in 2005. They detected two pulsation periods, 1950 and 2900 seconds.[11] The star's atmosphere contains 10,000 times more zirconium (per unit mass) than the Sun's; it also has between 1,000 and 10,000 times the amount of strontium, germanium and yttrium than the Sun. The heavy metals are believed to be in cloud layers in the atmosphere where the ions of each metal have a particular opacity that allows radiational levitation to balance gravitational settling.[8]

References

  1. ^ Nassau, J. J.; Stephenson, C. B. (1963). "Luminous Stars in the Northern Milky Way". Hamburger Sternw. 04. Bibcode:1963LS....C04....0N.
  2. ^ a b Zacharias, N.; Urban, S. E.; Zacharias, M. I.; Wycoff, G. L.; Hall, D. M.; Germain, M. E.; Holdenried, E. R.; Winter, L. (2003). "VizieR On-line Data Catalog: The Second U.S. Naval Observatory CCD Astrograph Catalog (UCAC2)". CDS/ADC Collection of Electronic Catalogues. 1289. Bibcode:2003yCat.1289....0Z.
  3. ^ a b Zacharias, N.; Finch, C. T.; Girard, T. M.; Henden, A.; Bartlett, J. L.; Monet, D. G.; Zacharias, M. I. (2012). "VizieR Online Data Catalog: UCAC4 Catalogue (Zacharias+, 2012)". VizieR On-line Data Catalog: I/322A. Originally Published in: 2012yCat.1322....0Z; 2013AJ....145...44Z. 1322. Bibcode:2012yCat.1322....0Z.
  4. ^ Drilling, J. S.; Jeffery, C. S.; Heber, U.; Moehler, S.; Napiwotzki, R. (2013). "An MK-like system of spectral classification for hot subdwarfs". Astronomy & Astrophysics. 551: A31. Bibcode:2013A&A...551A..31D. doi:10.1051/0004-6361/201219433.
  5. ^ Randall, S. K.; Bagnulo, S.; Ziegerer, E.; Geier, S.; Fontaine, G. (2015). "The enigmatic He-sdB pulsator LS IV-14°116: New insights from the VLT". Astronomy & Astrophysics. 576: A65. arXiv:1502.05520. Bibcode:2015A&A...576A..65R. doi:10.1051/0004-6361/201425251. S2CID 54615595.
  6. ^ Ahmad, A.; Jeffery, C. S. (2005). "Discovery of pulsation in a helium-rich subdwarf B star". Astronomy and Astrophysics. 437 (3): L51. Bibcode:2005A&A...437L..51A. doi:10.1051/0004-6361:200500136.
  7. ^ a b Green, E. M.; Guvenen, B.; O'Malley, C. J.; O'Connell, C. J.; Baringer, B. P.; Villareal, A. S.; Carleton, T. M.; Fontaine, G.; Brassard, P.; Charpinet, S. (2011). "The Unusual Variable Hot B Subdwarf LS IV-14°116". The Astrophysical Journal. 734 (1): 59. Bibcode:2011ApJ...734...59G. doi:10.1088/0004-637X/734/1/59. S2CID 122292750.
  8. ^ a b Naslim, N.; Jeffery, C. S.; Behara, N. T.; Hibbert, A. (2011). "An extremely peculiar hot subdwarf with a 10 000-fold excess of zirconium, yttrium and strontium". Monthly Notices of the Royal Astronomical Society. 412 (1): 363. arXiv:1010.5146. Bibcode:2011MNRAS.412..363N. doi:10.1111/j.1365-2966.2010.17909.x. S2CID 118469201.
  9. ^ Miller Bertolami, M. M.; Córsico, A. H.; Althaus, L. G. (2011). "On the Challenging Variability of LS IV-14°116: Pulsational Instabilities Excited by the epsilon-Mechanism". The Astrophysical Journal Letters. 741 (1): L3. arXiv:1109.4943. Bibcode:2011ApJ...741L...3M. doi:10.1088/2041-8205/741/1/L3. S2CID 118525163.
  10. ^ Jeffery, C. Simon (January 2011). "Photometric Variability of the Chemically Peculiar Hot Subdwarf LS IV-14 d116" (PDF). Information Bulletin on Variable Stars. 5964. Bibcode:2011IBVS.5964....1J. Retrieved 25 December 2024.
  11. ^ Ahmad, A.; Jeffery, C. S. (July 2005). "Discovery of pulsation in a helium-rich subdwarf B star" (PDF). Astronomy and Astrophysics. 437 (3): L51 – L54. Bibcode:2005A&A...437L..51A. doi:10.1051/0004-6361:200500136. Retrieved 25 December 2024.