HD 57197
Star in the constellation Puppis
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HD 57197, also known as M Puppis or HR 2789, is a suspected astrometric binary[13] located in the southern constellation Puppis, the poop deck. It has an apparent magnitude of 5.84,[3] making it faintly visible to the naked eye under ideal conditions. Based on parallax measurements from the Gaia satellite, the system is estimated to be 629 light years away from the Solar System.[2] The value is poorly constrained, but it appears to be receding with a heliocentric radial velocity of 13 km/s.[6] At its current distance, HD 57197's brightness is diminished by 0.3 magnitudes due to interstellar dust.[14] It has an absolute magnitude of -0.43.[1]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Puppis[1] |
| Right ascension | 07h 18m 04.24932s[2] |
| Declination | −43° 59′ 12.4288″[2] |
| Apparent magnitude (V) | 5.84±0.01[3] |
| Characteristics | |
| Spectral type | B8 II/III[4] |
| U−B color index | −0.47[5] |
| B−V color index | −0.14[5] |
| Astrometry | |
| Radial velocity (Rv) | 13±10[6] km/s |
| Proper motion (μ) | RA: −9.483 mas/yr[2] Dec.: −5.396 mas/yr[2] |
| Parallax (π) | 5.1842±0.0442 mas[2] |
| Distance | 629 ± 5 ly (193 ± 2 pc) |
| Absolute magnitude (MV) | −0.43[1] |
| Details | |
| Mass | 3.08[7] M☉ |
| Radius | 3.9±0.2[8] R☉ |
| Luminosity | 234[9] L☉ |
| Surface gravity (log g) | 3.77[7] cgs |
| Temperature | 12,596[9] K |
| Metallicity [Fe/H] | −0.18[7] dex |
| Age | 220[10] Myr |
| Other designations | |
| M Puppis, 85 G. Puppis[11], CD−43°3093, CPD−43°1430, GC 9732, HD 57197, HIP 35347, HR 2789, SAO 218618[12] | |
| Database references | |
| SIMBAD | data |
The visible component has a stellar classification of B8 II/III, indicating that it is an evolved B-type star with the blended luminosity class of a bright giant and a giant star. HD 57197 is estimated to be 220 million years old,[10] enough time for it to expand to 3.9 times the Sun's radius.[8] It has 3.08 times the mass of the Sun[7] and radiates 234 times the luminosity of the Sun from its photosphere at an effective temperature of 12,596 K,[9] giving it a bluish-white hue. Based on its extinction in the Gaia passband, it has an iron abundance 66% that of the Sun.[7] This makes HD 57197 metal deficient.