HD 68988
Star in the constellation Ursa Major
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HD 68988 is a star in the northern constellation of Ursa Major. It has the proper name Násti, which means star in the Northern Sami language. The name was selected in the NameExoWorlds campaign by Norway, during the 100th anniversary of the IAU.[8][9] HD 68988 is too faint to be seen with the naked eye, having an apparent visual magnitude of 8.20.[1] The star is located at a distance of 197 light-years from the Sun based on parallax. It is drifting closer with a radial velocity of −69 km/s and is predicted to come as close as 78 light-years in 617,000 years.[1]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ursa Major[1] |
| Right ascension | 08h 18m 22.17286s[2] |
| Declination | +61° 27′ 38.5950″[2] |
| Apparent magnitude (V) | 8.20[1] |
| Characteristics | |
| Spectral type | G0V[3] or G2V[4] or G2IV[1] |
| B−V color index | 0.652±0.015[1] |
| Astrometry | |
| Radial velocity (Rv) | −69.45±0.11[1] km/s |
| Proper motion (μ) | RA: 128.266 mas/yr[2] Dec.: 30.427 mas/yr[2] |
| Parallax (π) | 16.5598±0.0221 mas[2] |
| Distance | 197.0 ± 0.3 ly (60.39 ± 0.08 pc) |
| Absolute magnitude (MV) | 4.52[1] |
| Details[5] | |
| Mass | 1.16±0.01 M☉ |
| Radius | 1.08±0.01 R☉ |
| Luminosity | 1.297±0.002 L☉ |
| Surface gravity (log g) | 4.42±0.01 cgs |
| Temperature | 5919±11 K |
| Metallicity [Fe/H] | 0.29±0.01[1] dex |
| Rotational velocity (v sin i) | 6.4[6] km/s |
| Age | 1.0±0.4 Gyr |
| Other designations | |
| Násti, BD+61°1038, HD 68988, HIP 40687, SAO 14494[7] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
The stellar classification of HD 68988 has been given as G0V,[3] G2V,[4] and G2IV.[1] The age of this star was estimated as six billion years in 2002,[4] but was later revised down to one billion years in 2015.[5] It is rotating slowly and is chromospherically inactive.[10] The star has 16% more mass than the Sun and an 8% greater radius with a high metallicity; what astronomers term the abundance of heavier elements. It is radiating 1.3 times the luminosity of the Sun from its photosphere at an effective temperature of 5,919 K.[5]
Planetary system
There are two exoplanets: HD 68988 b was discovered in 2002[4] and HD 68988 c was discovered in 2006.[11] The orbit of the inner exoplanet is surprisingly eccentric for such a close in orbit, and over time it may become circularized,[10] although orbital parameters were significantly revised in 2021, resulting in wider orbit.[12] In 2025, the true mass of the planet was measured using astrometry, consistent with that of Rosenthal et al. (2021).[13]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (years) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b / Albmi | >1.972+0.017 −0.018 MJ |
0.0710+0.0012 −0.0014 |
0.017183893(34) | 0.1533+0.0049 −0.0048 |
— | — |
| c | 15.03+0.90 −0.75 MJ |
12.1±1.1 | 38.1+5.3 −4.9 |
0.399+0.046 −0.049 |
93+19 −23° |
— |