HD 146389

WASP-38 / Irena
Observation data
Epoch J2000      Equinox J2000
Constellation Hercules
Right ascension 16h 15m 50.36526s[1]
Declination 10° 01′ 57.2844″[1]
Apparent magnitude (V) 9.447±0.024[2]
Characteristics
Spectral type F8[3]
B−V color index 0.476
J−H color index 0.181
J−K color index 0.289
Astrometry
Radial velocity (Rv)−9.06±0.53[1] km/s
Proper motion (μ) RA: −31.073[1] mas/yr
Dec.: −39.171[1] mas/yr
Parallax (π)7.3115 ± 0.0429 mas[1]
Distance446 ± 3 ly
(136.8 ± 0.8 pc)
Details
Mass1.203±0.036[4] M☉
Radius1.331+0.030
−0.025[4] R☉
Luminosity2.838±0.024[1] L☉
Surface gravity (log g)4.25+0.012
−0.013[2] cgs
Temperature6,150±80[4] K
Metallicity [Fe/H]0.06[5] dex
Rotational velocity (v sin i)8.6±0.4[2] km/s
Age350 Myr[5]
400±500[6] Myr
Other designations
BD+10°2980, Gaia DR2 4453211899986180352, HD 146389, SAO 102042, 2MASS J16155036+1001572, WASP 38[7]
Database references
SIMBADdata

HD 146389 (also known as WASP-38), is a star with a yellow-white hue in the northern constellation of Hercules. The star was given the formal name Irena by the International Astronomical Union in January 2020.[8][9] It is invisible to the naked eye with an apparent visual magnitude of 9.4[2] The star is located at a distance of approximately 446 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −9 km/s.[1] The star is known to host one exoplanet, designated WASP-38b or formally named 'Iztok'.

The stellar classification of HD 146389 is F8,[3] which is an F-type star of uncertain luminosity class. The age of the star is uncertain. It shows a low lithium abundance, which suggests an age of more than 5 billion years. However, the rotation rate indicates an age closer to one billion.[2] The study in 2015 utilizing Chandra X-ray Observatory, have failed to detect any X-ray emissions from the star during planetary eclipse, which may indicate an unusually low coronal activity or the presence of absorbing gas ring formed by atmosphere escaping planet WASP-38 b.[10] The star is 33% larger and 20% more massive than the Sun.[4] It is radiating nearly three[1] times the luminosity of the Sun at an effective temperature of 6,150 K.[4]

  1. ^ a b c d e f g h i Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference Barros_et_al_2010 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Ehrenreich_Désert_2011 was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference Brown_et_al_2012 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Delgado_Mena_et_al_2015 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference bonfanti_et_al_2015 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference IAU was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference wasp was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Salz_et_al_2015 was invoked but never defined (see the help page).