HR 7578

A light curve for V4200 Sagittarii, plotted from Hipparcos data[1]
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]
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]
Distance46.01 ± 0.03 ly
(14.107 ± 0.008 pc)
Orbit[7]
PrimaryHR 7578A
CompanionHR 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
SIMBADdata
ARICNSdata

HR 7578 (also known as V4200 Sagittarii) is a binary star in the constellation of Sagittarius. 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]

References

  1. ^ "Light Curve". Hipparcos ESA. ESA. Retrieved 17 February 2022.
  2. ^ a b c d e f 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.
  3. ^ 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.
  4. ^ 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.
  5. ^ 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.
  6. ^ 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.
  7. ^ 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.
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