HD 87816

HD 87816
	Location of HD 87816 (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Vela
Right ascension	10h 06m 07.21043s
Declination	−52° 11′ 16.5788″
Apparent magnitude (V)	6.499±0.009
Characteristics
Evolutionary stage	Red clump
Spectral type	K1III
B−V color index	0.986
Astrometry
Radial velocity (Rv)	4.7±0.4 km/s
Proper motion (μ)	RA: −55.682 mas/yr ; Dec.: +16.413 mas/yr
Parallax (π)	7.4825±0.0196 mas
Distance	436 ± 1 ly ; (133.6 ± 0.4 pc)
Absolute magnitude (MV)	+0.876±0.013
Details
Mass	2.41±0.10 M☉
Radius	9.0±0.2 R☉
Luminosity	45±1 L☉
Surface gravity (log g)	2.860±0.096 cgs
Temperature	4,989±46 K
Metallicity [Fe/H]	+0.139±0.035 dex
Other designations
	R Vel (obsolete), CD−51°4471, HD 87816, HIP 49477, HR 3978, TYC 8194-294-1
Database references
SIMBAD	data

HD 87816 is a star in the constellation Vela. With an apparent magnitude of 6.499,^[3] it is very close to the average threshold for naked eye visibility, and can only be viewed from sufficiently dark skies, far from light pollution.^[8] Based on parallax measurements, it lies at a distance of 436 light-years.^[2] It is moving away from the Solar System at a velocity of 4.7 km/s.^[6]

The spectrum of this star matches a spectral class of K1III,^[5] with the luminosity class III indicating it is a giant star that has exhausted the hydrogen at its core. It is now fusing helium, being in the evolutionary stage known as the horizontal branch.^[4] The star has 2.4 times the Sun's mass, having grown to a radius 9.0 times the radius of the Sun. It shines with 45 times the Sun's luminosity at an effective temperature of 4,989 K.^[3] The temperature gives it the orange hue typical of K-type stars.^[9]

HD 87816 was once believed to be a variable star and received the variable-star designation R Velorum, but it is now considered a constant star.^[1]

Planetary system

HD 87816 hosts two known exoplanets, discovered in 2025 via Doppler spectroscopy. Both are gas giants, like Jupiter and Saturn.^[10]

Planet b has a minimum mass of 6.7 Jupiter masses (M_J). It takes 484 days (1.33 years) to complete an orbit around HD 87816 and has a very high orbital eccentricity of 0.78, among the highest of exoplanets orbiting giant stars.^[10]

Planet c has a minimum mass of 12.2 Jupiter masses. It takes 7,600 days (21 years) to complete an orbit around its host, and has a low eccentricity of 0.11.^[10]

The HD 87816 planetary system^[10]
Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (years)	Eccentricity	Inclination	Radius
b	≥6.74±0.13 $M$ _J	1.618±0.0003	1.3256+0.00036 −0.00033	0.780±0.005	—	—
c	≥12.20+2.15 −1.59 $M$ _J	10.14+0.99 −0.48	20.80+3.1 −1.46	0.19±0.07	—	—

References

^ ^a ^b "VSX: Detail for R Vel". AAVSO. Retrieved 2025-06-01.
^ ^a ^b ^c ^d ^e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
^ ^a ^b ^c ^d ^e ^f Ottoni, G.; Udry, S.; Ségransan, D.; Buldgen, G.; Lovis, C.; Eggenberger, P.; Pezzotti, C.; Adibekyan, V.; Marmier, M.; Mayor, M.; Santos, N. C.; Sousa, S. G.; Lagarde, N.; Charbonnel, C. (2022-01-01). "CORALIE radial-velocity search for companions around evolved stars (CASCADES). I. Sample definition and first results: Three new planets orbiting giant stars". Astronomy and Astrophysics. 657: A87. arXiv:2201.01528. Bibcode:2022A&A...657A..87O. doi:10.1051/0004-6361/202040078. ISSN 0004-6361. HD 87816's database entry at VizieR.
^ ^a ^b Adelman, Saul J. (2001). "On the Photometric Variability of Red Clump Giants". Baltic Astronomy. 10 (4): 593–597. Bibcode:2001BaltA..10..593A. doi:10.1515/astro-2001-0404. ISSN 1021-6766.
^ ^a ^b Houk, Nancy (1978). "Michigan catalogue of two-dimensional spectral types for the HD stars". Ann Arbor: Dept. Of Astronomy. Bibcode:1978mcts.book.....H. HD 87816's database entry at VizieR.
^ ^a ^b Gontcharov, G. A. (2006-11-01). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. ISSN 1562-6873. HD 87816's database entry at VizieR.
^ "HD 87816". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved June 1, 2024.
^ "Limiting Magnitude | COSMOS". astronomy.swin.edu.au. Retrieved 2025-06-01.
^ "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. Archived from the original on 2013-12-03. Retrieved 2012-01-16.
^ ^a ^b ^c ^d Fontanet, E.; Udry, S.; Ségransan, D.; Figueira, P.; Barroso, J. A. Acevedo; Akinsanmi, B.; Attia, M.; Battley, M.; Bhatnagar, S. (2025-05-20). "CORALIE radial-velocity search for companions around evolved stars (CASCADES) IV: New planetary systems around HD 87816, HD 94890, and HD 102888 and an update on HD 121056". Astronomy and Astrophysics. 699. arXiv:2505.14317. Bibcode:2025A&A...699A..38F. doi:10.1051/0004-6361/202554137.

[AAVSO-1] "VSX: Detail for R Vel". AAVSO. Retrieved 2025-06-01.

[DR3-2] Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.

[Otonni2022-3] ^ ^a ^b ^c ^d ^e ^f Ottoni, G.; Udry, S.; Ségransan, D.; Buldgen, G.; Lovis, C.; Eggenberger, P.; Pezzotti, C.; Adibekyan, V.; Marmier, M.; Mayor, M.; Santos, N. C.; Sousa, S. G.; Lagarde, N.; Charbonnel, C. (2022-01-01). "CORALIE radial-velocity search for companions around evolved stars (CASCADES). I. Sample definition and first results: Three new planets orbiting giant stars". Astronomy and Astrophysics. 657: A87. arXiv:2201.01528. Bibcode:2022A&A...657A..87O. doi:10.1051/0004-6361/202040078. ISSN 0004-6361. HD 87816's database entry at VizieR.

[Adelman2001-4] Adelman, Saul J. (2001). "On the Photometric Variability of Red Clump Giants". Baltic Astronomy. 10 (4): 593–597. Bibcode:2001BaltA..10..593A. doi:10.1515/astro-2001-0404. ISSN 1021-6766.

[Houk1978-5] Houk, Nancy (1978). "Michigan catalogue of two-dimensional spectral types for the HD stars". Ann Arbor: Dept. Of Astronomy. Bibcode:1978mcts.book.....H. HD 87816's database entry at VizieR.

[Gontcharov2006-6] Gontcharov, G. A. (2006-11-01). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. ISSN 1562-6873. HD 87816's database entry at VizieR.

[SIMBAD-7] "HD 87816". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved June 1, 2024.

[COSMOS-8] "Limiting Magnitude | COSMOS". astronomy.swin.edu.au. Retrieved 2025-06-01.

[csiro-9] "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. Archived from the original on 2013-12-03. Retrieved 2012-01-16.

[Fontanet2025-10] Fontanet, E.; Udry, S.; Ségransan, D.; Figueira, P.; Barroso, J. A. Acevedo; Akinsanmi, B.; Attia, M.; Battley, M.; Bhatnagar, S. (2025-05-20). "CORALIE radial-velocity search for companions around evolved stars (CASCADES) IV: New planetary systems around HD 87816, HD 94890, and HD 102888 and an update on HD 121056". Astronomy and Astrophysics. 699. arXiv:2505.14317. Bibcode:2025A&A...699A..38F. doi:10.1051/0004-6361/202554137.

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HD 87816

Planetary system

References

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