| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19h54m 17.17.7453s[2] |
| Declination | −23° 56′ 27.8630″[2] |
| Apparent magnitude (V) | 6.18[3] |
| Characteristics | |
| Spectral type | K3 V + K3 V[4] |
| U−B color index | +0.915[5] |
| B−V color index | +1.045[5] |
| Variable type | BY Dra[3] |
| Astrometry | |
| Radial velocity (Rv) | −5.1 ± 0.2[6] km/s |
| Proper motion (μ) | RA: −124.476±0.067[2] mas/yr Dec.: −410.440±0.043[2] mas/yr |
| Parallax (π) | 70.8873 ± 0.0399 mas[2] |
| Distance | 46.01 ± 0.03 ly (14.107 ± 0.008 pc) |
| Orbit[7] | |
| Primary | HR 7578A |
| Companion | HR 7578B |
| Period (P) | 46.816103±0.000057 d |
| Eccentricity (e) | 0.68640±0.00028 |
| Periastron epoch (T) | 2455441.0477±0.0030 HJD |
| Argument of periastron (ω) (secondary) | 241.168±0.046° |
| Semi-amplitude (K1) (primary) | 47.84±0.033 km/s |
| Semi-amplitude (K2) (secondary) | 48.686±0.031 km/s |
| Details | |
| Rotational velocity (v sin i) | 2.0[4] km/s |
| Other designations | |
CD−24° 15668, GJ 770, HD 188088, HIP 97944, HR 7578, SAO 188692 | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
HR 7578 (also known as V4200 Sagittarii) is a binary star in the constellationofSagittarius. Their combined apparent magnitude is 6.18.[3] Parallax measurements by the Gaia spacecraft put the system at 46.01 light-years (14.107 parsecs) away, making this a nearby system.[2]
The two stars of HR 7578 are fairly old, older than the Pleiades but possibly younger than the Hyades.[6] The stars are between 5×108 and 2×109 years old.[6] Both are K-type main-sequence stars.[4] Both stars have a minimum mass of 0.85 ± 0.03 M☉, and are unusually metal-rich, showing high amounts of cyanide and sodium in their spectra.[6]
HR 7578 is a BY Draconis variable. This is a class of variable star whose variability comes from starspots on the stars' surfaces. HR 7578 also has a common proper motion companion, 2MASS J19542064−2356398. It is a red dwarf that is at least 580 astronomical units from the central star system.[3]
