59 Serpentis
Multiple star systemin the constellation Serpens
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59 Serpentis, also known as d Serpentis, is a multiple star in the constellation Serpens.[2] The system shows irregular variations in brightness between magnitudes 5.17 and 5.29.[3]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Serpens |
| Right ascension | 18h 27m 12.50775s[2] |
| Declination | +00° 11′ 45.9912″[2] |
| Apparent magnitude (V) | 5.17 – 5.29[3] |
| Characteristics | |
| Spectral type | A0Vs + G:III[2] |
| U−B color index | +0.21[4] |
| B−V color index | +0.48[4] |
| Variable type | Irregular?[3] |
| Astrometry | |
| Radial velocity (Rv) | −23.3[5] km/s |
| Proper motion (μ) | RA: −3.67[6] mas/yr Dec.: −8.61[6] mas/yr |
| Parallax (π) | 6.95±0.63 mas[6] |
| Distance | 470 ± 40 ly (140 ± 10 pc) |
| Absolute magnitude (MV) | −0.57[7] |
| Details | |
| Aa | |
| Mass | 6.32[8] M☉ |
| Radius | 13[9] R☉ |
| Temperature | 5,093[10] K |
| Age | 316[10] Myr |
| Ab1 | |
| Mass | 4.13[8] M☉ |
| Radius | 2.2[9] R☉ |
| Temperature | 9,700[9] K |
| Ab2 | |
| Mass | 3.39[8] M☉ |
| Radius | 1.8[9] R☉ |
| Temperature | 9,700[9] K |
| Ba | |
| Mass | 3.17[8] M☉ |
| Radius | 1.7[11] R☉ |
| Luminosity | 10.1[11] L☉ |
| Surface gravity (log g) | 4.28[11] cgs |
| Temperature | 7,981[11] K |
| Other designations | |
| 59 Ser, d Ser, HIP 90441, HR 6918, BD+00°3936, ADS 11353, CCDM J18272+0012 | |
| A: HD 169985 | |
| B: HD 169985 | |
| Database references | |
| SIMBAD | data |
| A | |
| B | |
Components
59 Serpentis appears as a close pair of stars, of 5th magnitude and 7th magnitude respectively, separated by four arc-seconds. The brighter of the two is itself an even closer binary with the two stars separated by only 0.2″, and only 0.1″ when they were first detected. The stars are designated Aa, Ab, and B.[12]
The primary star, component Aa, is a G0 giant. Component Ab is spectroscopic binary with a period of 1.85 days; the two stars are very similar A-class main sequence stars. Component B is an F5V possible astrometric binary, but with little known about the orbit or the possible companion.[8]
A much fainter star 20″ away is also thought to be a member of the system, having a common proper motion and similar parallax, and is designated as component C.[8]
The first detailed orbital solution for this triple system was published in 1943 by Elizabeth Cornwall Tilley.[9] Her work established that 59 Serpentis A consists of a G-type giant star (component Aa) and a close pair of two A-type main-sequence stars (forming component Ab).
Tilley's 1943 paper also provided the first estimates for the radii of the stars in the triple system: approximately 13 R☉ for the G-type giant, and 2.2 R☉ and 1.8 R☉ for the two A-type stars.[9]