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25 Sextantis

25 Sextantis
Location of 25 Sex on the map (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sextans
Right ascension 10h 23m 26.47823s[1]
Declination −04° 04′ 26.5182″[1]
Apparent magnitude (V) 5.97[2] (5.94 - 5.98)[3]
Characteristics
Evolutionary stage main sequence star[4]
Spectral type B9p Si(CrSr)[5]
U−B color index −0.17[2]
B−V color index −0.10[2]
Variable type α2 CVn[3]
Astrometry
Radial velocity (Rv)23.0±3.4[6] km/s
Proper motion (μ) RA: −50.818 mas/yr[1]
Dec.: +4.114 mas/yr[1]
Parallax (π)9.4414 ± 0.0598 mas[1]
Distance345 ± 2 ly
(105.9 ± 0.7 pc)
Absolute magnitude (MV)+0.86[7]
Details
Mass2.48±0.07[4] M☉
Radius2.22±0.11[8] R☉
Luminosity45.7+13.2
−10.2[9] L☉
Surface gravity (log g)4.14[10] cgs
Temperature11,500[11] K
Metallicity [Fe/H]−0.19[10] dex
Rotational velocity (v sin i)24±3[9] km/s
Age309+54
−80[4] Myr
Other designations
25 Sex, 43 G. Sextantis[12], SS Sextantis, BD−03°2911, FK5 388, GC 14268, HD 90044, HIP 50885, HR 4082, SAO 137533, TIC 1712781[13]
Database references
SIMBADdata

25 Sextantis (HD 90044; HR 4082; 43 G. Sextantis), or simply 25 Sex, is a star located in the equatorial constellation Sextans; it also bears the variable star designation SS Sextantis (SS Sex). With an average apparent magnitude of 5.97,[2] 25 Sex is barely visible to the naked eye, even under ideal conditions. Gaia DR3 parallax measurements imply a distance of 345 light-years,[1] and it is currently drifting away with a heliocentric radial velocity of approximately 23 km/s.[6] At its current distance, 25 Sex's average brightness is diminished by an interstellar extinction of 0.17 magnitudes and it has an absolute magnitude of +0.86.[7]

A light curve for SS Sextantis, plotted from TESS data.[14] The 4.37 day rotation period is shown in red.

The star was first discovered to be variable in 1980 by French astronomers P. Renson & J. Manfroid. They observed a 4.37 day period for 25 Sex and a flucation of 0.03 magnitudes in optical light.[15] The next year, it was confirmed to be variable and it was given the variable star designation SS Sextantis.[16] J. Manfroid and G. Mathys refined the period of 25 Sextantis to be slightly longer than previously measured; the period of SS Sextantis was measured at 4.39 days but with a larger uncertainty.[17] In 1993, D. A. Bohlender and colleagues measured the magnetic field of the star and found that it varied between 650 and 1,200 gauss, although with some uncertainty about the variation.[18] Subsequent observations provide a much wider range between 1 and -1,000 gauss.[19]

25 Sex has a stellar classification of B9pSi(CrSr),[5] indicating that it is a Bp star with abundance of silicon, chromium, and strontium in its spectrum. It has 2.48 times the mass of the Sun[4] and 2.22 times the radius of the Sun.[8] It radiates 45.7 times the luminosity of the Sun[9] from its photosphere at an effective temperature of roughly 11,500 K,[11] giving it a bluish-white hue when viewed in the night sky. 25 Sex is metal deficient with an iron abundance 64.6% of the Sun's[10] and it is estimated to be 309 million years old.[4] At that age, it has completed 56% of its main sequence lifetime.[4] Like many chemically peculiar stars it spins modestly—having a projected rotational velocity of 24 km/s.[9]

  1. ^ a b c d e Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Ducati2002 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  4. ^ a b c d e f Cite error: The named reference Kochukov2006 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Cowley1969 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Kervella2004 was invoked but never defined (see the help page).
  9. ^ a b c d Cite error: The named reference Netopli2017 was invoked but never defined (see the help page).
  10. ^ a b c Cite error: The named reference Anders2019 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference Floquet1981 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Gould1879 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Manfroid1980 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Kholpov1981 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Manfroid1985 was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference Bohlender1993 was invoked but never defined (see the help page).
  19. ^ Cite error: The named reference Leone2001 was invoked but never defined (see the help page).
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