17 Delphini
Suspected variable star in Delphinus
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17 Delphini is a solitary[11] star in the northern constellation of Delphinus. It has an absolute magnitude of −0.64[7] and apparent magnitude of 5.18,[2] allowing it to be faintly seen with the naked eye. Located 517 light years away,[1] it is approaching the Solar System with a heliocentric radial velocity of −10.2 km/s.[6]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Delphinus |
| Right ascension | 20h 55m 36.689s[1] |
| Declination | +13° 43′ 17.53″[1] |
| Apparent magnitude (V) | 5.18[2] (5.16-5.27)[3] |
| Characteristics | |
| Evolutionary stage | red giant branch[1] |
| Spectral type | K0 III[4] |
| U−B color index | +0.95[5] |
| B−V color index | +1.13[5] |
| Variable type | suspected[3] |
| Astrometry | |
| Radial velocity (Rv) | −10.2±0.9[6] km/s |
| Proper motion (μ) | RA: +16.457 mas/yr[1] Dec.: −11.468 mas/yr[1] |
| Parallax (π) | 6.3132±0.0699 mas[1] |
| Distance | 517 ± 6 ly (158 ± 2 pc) |
| Absolute magnitude (MV) | −0.64[7] |
| Details[8] | |
| Mass | 2.33 M☉ |
| Radius | 23.36 R☉ |
| Luminosity | 219 L☉ |
| Surface gravity (log g) | 2.07 cgs |
| Temperature | 4,616 K |
| Metallicity [Fe/H] | −0.19[9] dex |
| Rotational velocity (v sin i) | 3±1[10] km/s |
| Age | 832 Myr |
| Other designations | |
| 17 Del, AG+13°2209, BD+13°4572, FK5 3669, GC 29201, HD 199253, HIP 103294, HR 8011, SAO 106665 | |
| Database references | |
| SIMBAD | data |
17 Delphini is an orange giant that is most likely on the horizontal branch (84% probability).[8] At present it has 2.33 times the mass of the Sun, but at an age of 832 million years — has expanded to 23.36 times the radius of the Sun.[8] It shines at 219 solar luminosities from its enlarged photosphere at an effective temperature of 4,616 K,[8] giving it an orange glow. 17 Del has an iron abundance 64% that of the Sun[9] and spins modestly with a projected rotational velocity of 3 km/s.[10]
17 Del is suspected to be a variable star of unknown type ranging from 5.16 to 5.27.[3]