HR 7578 (also known as V4200 Sagittarii) is a triple star system in the constellation of Sagittarius. Their combined apparent magnitude is 6.18.[3] Parallax measurements by the Gaia spacecraft put the system at 46 light-years (14.1 parsecs) away, making this a nearby system.[2]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19h 54m 17.17.7453s[2] |
| Declination | −23° 56′ 27.8630″[2] |
| Apparent magnitude (V) | 6.18[3] |
| Characteristics | |
| Spectral type | K3 V + K3 V[4] + M5[5] |
| U−B color index | +0.915[6] |
| B−V color index | +1.045[6] |
| Variable type | BY Dra[3] |
| Astrometry | |
| Radial velocity (Rv) | −5.1 ± 0.2[7] km/s |
| Proper motion (μ) | RA: −124.476±0.067[2] mas/yr Dec.: −410.440±0.043[2] mas/yr |
| Parallax (π) | 70.857 ± 0.019 mas[5] |
| Distance | 46.03 ± 0.01 ly (14.113 ± 0.004 pc) |
| Orbit[5] | |
| Primary | HR 7578A |
| Companion | HR 7578B |
| Period (P) | 46.81614±0.00003 d |
| Semi-major axis (a) | 0.3054±0.0001 au″ |
| Eccentricity (e) | 0.68664±0.00006 |
| Inclination (i) | 99.048±0.007° |
| Longitude of the node (Ω) | 111.83±0.01° |
| Periastron epoch (T) | 2455441.0406±0.0003 HJD |
| Argument of periastron (ω) (secondary) | 241.056±0.011° |
| Semi-amplitude (K1) (primary) | 47.79±0.01 km/s |
| Semi-amplitude (K2) (secondary) | 48.63±0.01 km/s |
| Details | |
| HR 7578A | |
| Mass | 0.87492±0.00032[5] M☉ |
| Radius | 1.59±0.62[5] R☉ |
| Luminosity | 1.22[5] L☉ |
| Temperature | 4820±200[5] K |
| Metallicity [Fe/H] | 0.28[5] dex |
| Rotational velocity (v sin i) | 2.0[4] km/s |
| HR 7578B | |
| Mass | 0.85978±0.00029[5] M☉ |
| Radius | 1.57±0.62[5] R☉ |
| Luminosity | 1.20[5] L☉ |
| Temperature | 4820±200[5] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
The two main stars of HR 7578 are fairly old, older than the Pleiades but possibly younger than the Hyades.[7] The stars are between 5×108 and 2×109 years old.[7] 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.[7]
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] There is another star that is separated about 40″ away and is 4.4 magnitudes fainter, but is not physically associated with HR 7578.[8]
References
edit- ^ "Light Curve". Hipparcos ESA. ESA. Retrieved 17 February 2022.
- ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b c d Chini, R.; Fuhrmann, K.; Barr, A.; Pozo, F.; Westhues, C.; Hodapp, K. (2014). "New visual companions of solar-type stars within 25 pc". Monthly Notices of the Royal Astronomical Society. 437 (1): 879–886. arXiv:1310.2684. Bibcode:2014MNRAS.437..879C. doi:10.1093/mnras/stt1953. S2CID 118717758.
- ^ a b c Pasquini, L.; Cortés, C.; Lombardi, M.; Monaco, L.; Leão, I. C.; Delabre, B. (2015). "Tachoastrometry: Astrometry with radial velocities". Astronomy & Astrophysics. 574: A76. arXiv:1412.7075. Bibcode:2015A&A...574A..76P. doi:10.1051/0004-6361/201424882. S2CID 55059342.
- ^ a b c d e f g h i j k l Gallenne, A.; Mérand, A.; Kervella, P.; Graczyk, D.; Pietrzyński, G.; Gieren, W.; Pilecki, B. (2023-04-01). "The Araucaria project: High-precision orbital parallaxes and masses of binary stars. I. VLTI/GRAVITY observations of ten double-lined spectroscopic binaries". Astronomy and Astrophysics. 672: A119. arXiv:2302.12960. Bibcode:2023A&A...672A.119G. doi:10.1051/0004-6361/202245712. ISSN 0004-6361.
- ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
- ^ a b c d Fekel, F. C. Jr.; Beavers, W. I. (1983). "HR 7578 - A K dwarf double-lined spectroscopic binary with peculiar abundances". The Astrophysical Journal. 267: 682. Bibcode:1983ApJ...267..682F. doi:10.1086/160905.
- ^ Fekel, Francis C.; Henry, Gregory W.; Tomkin, Jocelyn (2017). "New Precision Orbits of Bright Double-lined Spectroscopic Binaries. X. HD 96511, HR 7578, and KZ Andromedae". The Astronomical Journal. 154 (3). 120. Bibcode:2017AJ....154..120F. doi:10.3847/1538-3881/aa816e.