HD 142990

HD 142990

A light curve for V913 Scorpii, plotted from Kepler K2 data.[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Scorpius
Right ascension 15h 58m 34.86657s[2]
Declination −24° 49′ 53.3617″[2]
Apparent magnitude (V) 5.40 - 5.47[3]
Characteristics
Spectral type B5 V[4]
U−B color index -0.65[5]
B−V color index -0.09[5]
Variable type SXARI[3]
Astrometry
Proper motion (μ) RA: −12.451±0.100[2] mas/yr
Dec.: −24.582±0.061[2] mas/yr
Parallax (π)7.0050 ± 0.0908 mas[2]
Distance466 ± 6 ly
(143 ± 2 pc)
Details
Mass5.7±0.1[6] M☉
Radius2.80±0.04[6] R☉
Luminosity794[6] L☉
Surface gravity (log g)4.15±0.11[6] cgs
Temperature18000±500[6] K
Rotation0.978832±0.000002 d[7]
Rotational velocity (v sin i)122±2[8] km/s
Age5.0+1.3
−1.0[9] Myr
Other designations
V913 Sco, HR 5942, HIP 78246, SAO 183982[10]
Database references
SIMBADdata

HD 142990, also known as HR 5942 and V913 Scorpii, is a star about 470 light years from the Earth, in the constellation Scorpius.[2] It is a 5th magnitude star, so it will be faintly visible to the naked eye of an observer far from city lights.[2] It is a variable star, whose brightness varies slightly from 5.40 to 5.47 during its 23.5 hour rotation period.[11][3] It is a member of the Upper Scorpius Region of the Scorpius–Centaurus association.[12]

HD 142990 is a helium-weak star.[13] In 1983, Ermanno Borra et al. detected the star's strong (~kilogauss) magnetic field from the Zeeman splitting of the Hβ spectral line.[13] Later estimates put the field strength as several kilogauss.[9]

The variability of HD 142990 was discovered in 1977 by Holger Pedersen and Bjarne Thomsen, during a spectroscopic and photometric study of helium weak and helium strong stars.[14] In 1978 the star was given the variable star designation V913 Scorpii.[15] Far more extensive photometric data were provided by the Kepler K2 program, which sampled the light curve well, and allowed Dominic Bowman et al. to measure the star's 0.978832±0.000002 day rotation period.[7]

The rotation period of HD 142990 appears to be decreasing at a rate of about 0.6 seconds per year. This might mean the star is still contracting towards the zero-age main sequence, though other explanations involving magnetohydrodynamics have been proposed.[16]

In 1989, Jeffrey Linsky et al. reported the detection of 6 cm radio emission from HD 142990, which appeared to be variable on a time scale of 5 minutes.[17] In 2018, Emil Lenc et al. found that the radio emission from the star is circularly polarized.[18] In 2019, Barnali Das et al. reported that HD 142990 exhibits coherent electron cyclotron maser emission at 200 MHz, making it, at that time, only the fourth hot magnetic star known to emit by this mechanism .[6]

  1. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  2. ^ a b c d e f g Cite error: The named reference dr3 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference GCVS was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Houk1988 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Garrison1967 was invoked but never defined (see the help page).
  6. ^ a b c d e f Cite error: The named reference Das2019 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Bowman2018 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Shultz2018 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Shultz2016 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference IVSI was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Bertiau1958 was invoked but never defined (see the help page).
  13. ^ a b Cite error: The named reference Borra1983 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Pedersen1977 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Kholopov1979 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Shultz2019 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Linsky1989 was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference Lenc2018 was invoked but never defined (see the help page).