R Puppis
Variable star in the constellation Puppis
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R Puppis is a variable star in the constellation Puppis. It is a rare yellow hypergiant and a candidate member of the open cluster NGC 2439. It is also an MK spectral standard for the class G2 0-Ia.[9]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Puppis |
| Right ascension | 07h 40m 52.597s[1] |
| Declination | −31° 39′ 40.20″[1] |
| Apparent magnitude (V) | 6.50 - 6.71[2] |
| Characteristics | |
| Spectral type | G2 0-Ia[3] |
| U−B color index | +0.85[4] |
| B−V color index | +1.18[4] |
| Variable type | SRd[2] |
| Astrometry | |
| Radial velocity (Rv) | +68.22[1] km/s |
| Proper motion (μ) | RA: −2.251[1] mas/yr Dec.: +3.222[1] mas/yr |
| Parallax (π) | 0.2440±0.0180 mas[1] |
| Distance | 13,400 ± 1,000 ly (4,100 ± 300 pc) |
| Absolute magnitude (MV) | −7.8[5] |
| Details | |
| Mass | 14.3[6] M☉ |
| Radius | 245±22[7] R☉ |
| Luminosity | 95,500+22,000 −20,000[7] L☉ |
| Surface gravity (log g) | 0.30[8] cgs |
| Temperature | 4,100±68[8] K |
| Metallicity [Fe/H] | −0.25[8] dex |
| Other designations | |
| CD−31°4910, GSC 07106-03582, HIP 37415, HR 2974, HD 62058 | |
| Database references | |
| SIMBAD | data |
Variability
R Puppis was identified as a variable star in 1879, and described as having a range of over a magnitude.[11] Numerous observations over the following 100 years failed to confirm the variations, until the 1970s when clear brightness changes were observed.[12] These were confirmed by later observations, but with a total visual amplitude of only about 0.2 magnitudes.[11]
Variable stars such as R Puppis have been described as pseudo-Cepheids, because they lie above the high-luminosity portion of the instability strip and their variations are similar to those of Cepheids although less regular.[11] R Puppis is formally classified as a semiregular variable of type SRd, meaning F, G, or K giants or supergiants.[2]