HD 137388

Last updated
HD 137388 / Karaka
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Apus
Right ascension 15h 35m 39.921s [1]
Declination −80° 12′ 16.54″ [1]
Apparent magnitude  (V)8.70 [2]
Characteristics
Evolutionary stage subgiant
Spectral type K2IV [3] or K0/K1V [4]
B−V color index 0.891±0.017 [5]
Astrometry
Radial velocity (Rv)+26.01±0.0327 [1]  km/s
Proper motion (μ)RA: −49.570 [1]   mas/yr
Dec.: 41.135 [1]   mas/yr
Parallax (π)24.6722 ± 0.0327  mas [1]
Distance 132.2 ± 0.2  ly
(40.53 ± 0.05  pc)
Absolute magnitude  (MV)5.75 [5]
Details [6]
Mass 0.930+0.024
−0.035  M☉
Radius 0.86±0.01  R☉
Luminosity 0.528 [1]   L☉
Surface gravity (log g)4.449±0.434  cgs
Temperature 5,297±20  K
Metallicity [Fe/H]+0.29  dex
Rotational velocity (v sin i)2.207±0.356 km/s
Age 2.991+2.629
−1.902  Gyr
Other designations
Karaka, NSV  7116, CPD–79°844, Gaia DR2  5778418870846853888, HD  137388, HIP  76351, 2MASS J15353994-8012164 [7]
Database references
SIMBAD data

HD 137388 is an orange-hued star in the southern constellation of Apus. It has the proper name Karaka, after the native New Zealand karaka tree. The name was assigned by representatives of New Zealand in the IAU's NameExoWorlds contest. [8] The star is too faint to be visible to the naked eye, having an apparent visual magnitude of 8.70. [2] It is located at a distance of 132  light years from the Sun based on parallax. The star is drifting further away with a radial velocity of +26 km/s, having come as close as 52.9 light-years some 1.2 million years ago. [5] It has an absolute magnitude of 5.75. [5]

The stellar classification of HD 137388 is K2IV, [3] matching that of an evolving subgiant star. However, in 2011 Dumusque and colleagues found a class of K0/K1V, suggesting it is instead a K-type main-sequence star. [4] It is around three billion years old and is spinning with a projected rotational velocity of 2.2 km/s. [6] The star shows a magnetic activity cycle, similar to the solar cycle. [4] It has 93% of the mass of the Sun and 86% of the Sun's radius. Based on the abundance of iron in the spectrum, it is a high metallicity star with a greater abundance of heavy elements compared to the Sun. The star is radiating 53% of the luminosity of the Sun from its photosphere at an effective temperature of 5,297 K. [6]

Planetary system

Radial velocity studies indicate that it has a planet, originally named HD 137388 b (mass 0.223 MJ, period 330d). It orbits at a typical distance of 0.89 AU with an eccentricity of 0.36, [4] [9] completely overlapping the star's habitable zone. [10] The planet was officially designated Kererū, the Māori name of the New Zealand pigeon, by the IAU in the same contest that named its parent star. [8]

The HD 137388 planetary system [9]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b (Kererū) 0.223±0.029  MJ 0.89±0.02330.0±4.00.36±0.1286.0±35.0° —

Related Research Articles

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HD 8574 is a single star in the equatorial constellation of Pisces. It can be viewed with binoculars or a telescope, but not with the naked eye having a low apparent visual magnitude of +7.12. The distance to this object is 146 light years based on parallax, and it has an absolute magnitude of 3.88. The star is drifting further away from the Sun with a radial velocity of +18 km/s. It has a relatively high proper motion, advancing across the celestial sphere at the rate of 0.298 arc seconds per annum.

HD 23079 is a star in the southern constellation of Reticulum. Since the star has an apparent visual magnitude of 7.12, it is not visible to the naked eye, but at least in binoculars it should be easily visible. Parallax measurements give a distance estimate of 109 light years from the Sun. it is slowly drifting further away with a radial velocity of +0.65 km/s.

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HD 20003 is a star in the southern constellation Hydrus. With an apparent visual magnitude of 8.39, this yellow-hued star is much too faint to be visible to the naked eye. It is located at a distance of 136.6 light years from the Sun based on parallax. HD 20003 is drifting closer with a radial velocity of −16 km/s, and is predicted to come to within 97 light-years in around 1.4 million years from now.

HD 7199 is a star in the constellation Tucana located 118 light years distance from the Sun based on parallax. It has an orange hue but is too dim to be viewed with the naked eye, having an apparent visual magnitude of +8.06. The star is drifting further away from the Sun with a radial velocity of +5.6 km/s.

References

  1. 1 2 3 4 5 6 7 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.
  2. 1 2 Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H.
  3. 1 2 Gray, R. O.; et al. (2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv: astro-ph/0603770 . Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID   119476992.
  4. 1 2 3 4 Dumusque, X.; et al. (2011). "The HARPS Search for Southern Extra-solar Planets. XXX. Planetary Systems around Stars with Solar-like Magnetic Cycles and Short-term Activity Variation". Astronomy & Astrophysics. 535: A55–A66. arXiv: 1107.1748 . Bibcode:2011A&A...535A..55D. doi:10.1051/0004-6361/201117148. S2CID   119192207.
  5. 1 2 3 4 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv: 1108.4971 . Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID   119257644.
  6. 1 2 3 Soto, M. G.; Jenkins, J. S. (2018). "Spectroscopic Parameters and atmosphEric ChemIstriEs of Stars (SPECIES). I. Code description and dwarf stars catalogue". Astronomy and Astrophysics. 615: A76. arXiv: 1801.09698 . Bibcode:2018A&A...615A..76S. doi:10.1051/0004-6361/201731533. S2CID   119107228.
  7. ↑ "HD 137388". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2020-12-25.
  8. 1 2 "Approved names (§ New Zealand)". Name Exo Worlds. IAU . Retrieved 19 December 2019.
  9. 1 2 "HD 137388b". Extrasolar Planets Encyclopaedia . Retrieved 20 September 2015.
  10. ↑ Agnew, Matthew T.; et al. (2017). "Stable habitable zones of single Jovian planet systems". Monthly Notices of the Royal Astronomical Society. 471 (4): 4494–4507. arXiv: 1706.05805 . Bibcode:2017MNRAS.471.4494A. doi:10.1093/mnras/stx1449. S2CID   119227856.
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