HR 7578

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] + 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]
Distance46.03 ± 0.01 ly
(14.113 ± 0.004 pc)
Orbit[5]
PrimaryHR 7578A
CompanionHR 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
Mass0.87492±0.00032[5] M☉
Radius1.59±0.62[5] R☉
Luminosity1.22[5] L☉
Temperature4820±200[5] K
Metallicity [Fe/H]0.28[5] dex
Rotational velocity (v sin i)2.0[4] km/s
HR 7578B
Mass0.85978±0.00029[5] M☉
Radius1.57±0.62[5] R☉
Luminosity1.20[5] L☉
Temperature4820±200[5] K
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 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]

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]

  1. ^ Cite error: The named reference HIPCurve was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference Gaia DR2 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference Chini was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference Pasquini was invoked but never defined (see the help page).
  5. ^ 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.
  6. ^ a b Cite error: The named reference EgUBV was invoked but never defined (see the help page).
  7. ^ a b c d Cite error: The named reference Fekel was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Fekel2017 was invoked but never defined (see the help page).