HD 175535 is a binary star system in the northern circumpolar constellation of Draco. It has an apparent visual magnitude of 4.92,[2] which is bright enough to be faintly visible to the naked eye. The system is located about 302 light years away, as determined from its annual parallax shift of 10.8 mas.[1] It is moving further from the Earth with a heliocentric radial velocity of +8.5 km/s.[2]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Draco |
| Right ascension | 18h 53m 13.55478s[1] |
| Declination | +50° 42′ 59.1821″[1] |
| Apparent magnitude (V) | 4.92[2] |
| Characteristics | |
| Spectral type | G7 IIIa Fe−1[3] |
| U−B color index | 0.57[4] |
| B−V color index | 0.90[2] |
| Astrometry | |
| Radial velocity (Rv) | +8.5[2] km/s |
| Proper motion (μ) | RA: 0.938 mas/yr Dec.: −24.171 mas/yr |
| Parallax (π) | 10.7890 ± 0.2187 mas[1] |
| Distance | 302 ± 6 ly (93 ± 2 pc) |
| Absolute magnitude (MV) | −0.78[5] |
| Orbit[4] | |
| Period (P) | 972.84±0.35 d |
| Eccentricity (e) | 0.342±0.006 |
| Periastron epoch (T) | 53,678.2±2.4 |
| Argument of periastron (ω) (secondary) | 190.0±1.1° |
| Semi-amplitude (K1) (primary) | 5.83±0.04 km/s |
| Details | |
| Mass | 3.27[2] M☉ |
| Radius | 13[6] R☉ |
| Luminosity | 219[2] L☉ |
| Surface gravity (log g) | 2.85±0.15[7] cgs |
| Temperature | 5,024±74[2] K |
| Metallicity [Fe/H] | −0.07±0.07[7] dex |
| Rotational velocity (v sin i) | 2.3[8] km/s |
| Age | 320[2] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The binary nature of this system was announced by W. W. Campbell of the Lick Observatory in 1911. It is a single-lined spectroscopic binary with an orbital period of 2.66 years (972.84 d) and an eccentricity of 0.342. The a sin i value for the visible component is 73.4±0.6 Gm, where a is the semimajor axis and i is the (unknown) orbital inclination.[4] This indicates that the actual semimajor axis is larger than 0.49 AU.[10]
The visible component appears to be an evolved giant star with a stellar classification of G7 IIIa Fe−1,[3] where the suffix notation indicates an underabundance of iron in the atmosphere. It is 320[2] million years old with 3.27[2] times the mass of the Sun and about 13[6] times the Sun's radius. The star is radiating 219[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 5,024 K.[2]