HD 47366

HD 47366

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Canis Major
Right ascension	06^h 37^m 40.79354^s[1]
Declination	−12° 59′ 06.4138″[1]
Apparent magnitude (V)	6.12[2]
Characteristics
Spectral type	K1III:[3]
B−V color index	0.977[3]
Astrometry
Radial velocity (Rv)	9.01[3] km/s
Proper motion (μ)	RA: +10.32[1] mas/yr Dec.: −124.46[1] mas/yr
Parallax (π)	12.50 ± 0.42[1] mas
Distance	261 ± 9 ly (80 ± 3 pc)
Absolute magnitude (MV)	1.459[3]
Details
Mass	1.81±0.13[4] M☉
Radius	7.30±0.33[4] R☉
Luminosity	26.1±1.8[4] L☉
Surface gravity (log g)	2.60[3] cgs
Temperature	4,772[3] K
Metallicity [Fe/H]	−0.16[3] dex
Rotation	< 86[4] d
Rotational velocity (v sin i)	4.3±0.8[4] km/s
Age	1.61±0.53[4] Gyr
Other designations
BD−12° 1566, HD 47366, HIP 31674, HR 2437, SAO 151725.[5]

HD 47366 is the Henry Draper Catalogue designation for a star in the southern constellation of Canis Major. It has an apparent visual magnitude of 6.12,^[2] which puts it near the lower limit of stars visible to the naked eye. According to the Bortle scale, it can be viewed from dark rural skies. Parallax measurements performed by the Hipparcos spacecraft provide a distance estimate of roughly 261 light-years (80 parsecs).^[1]

This is a K-type giant star with a stellar classification of K1III: − the colon suffix indicates some uncertainty in the luminosity classification of III.^[3] Spectroscopic analysis of the star was used to derive an estimated mass of about 1.81 times the mass of the Sun. It has an estimated age of 1.6 billion years; old enough at that mass to have evolved off the main sequence. As a giant star, the atmosphere has expanded to 7.3 times the Sun's radius, and it is emitting 26 times the solar luminosity at an effective temperature of 4,772 K. The projected rotational velocity of the star is 4.3 km/s, indicating it is rotating with a period of under 86 days.^[4]

In 2016, a team of astronomers reported the detection of a pair of giant planetary companions. Radial velocity measurements indicated gravitational perturbations of the star being caused by orbiting objects. The best fit to the preliminary data suggests two periodicities: one about a year long and a second of around two years. Both objects are predicted to have masses greater than that of the planet Jupiter: their minimum masses are 1.8 and 1.9 Jupiter masses, respectively. Until the inclination of their orbits is known, their actual masses cannot be pinned down more accurately.^[4]

The HD 47366 planetary system^[4]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥ 1.75+0.20 −0.17 MJ	1.214+0.030 −0.029	363.3+2.5 −2.4	0.089+0.079 −0.060	—	—
c	≥ 1.86+0.16 −0.15 MJ	1.853+0.045 −0.045	684.7+5.0 −4.9	0.278+0.069 −0.094	—	—

References

1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
2. Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa 27: 11, Bibcode:1968MNSSA..27...11C.
3. Soubiran, C.; et al. (March 2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics 480 (1): 91–101, arXiv:0712.1370, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788.
4. Sato, Bun'ei; et al. (January 18, 2016), A Pair of Giant Planets around the Evolved Intermediate-Mass Star HD 47366: Multiple Circular Orbits or a Mutually Retrograde Configuration, arXiv:1601.04417, Bibcode:2016ApJ...819...59S, doi:10.3847/0004-637X/819/1/59.
5. "HR 2437 -- Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), retrieved 2016-01-21.

External links

• Nowakowski, Tomasz (January 21, 2016), "Two giant planets detected around an evolved intermediate-mass star", Physorg.org.