HR 7578

HR 7578

A light curve for V4200 Sagittarii, plotted from Hipparcos data
Observation data
Epoch J2000      Equinox ICRS
Constellation Sagittarius
A
Right ascension 19h 54m 17.7453s
Declination −23° 56′ 27.863″
Apparent magnitude (V) 6.18
Characteristics
A
Spectral type K3 V + K3 V + M5
U−B color index +0.915
B−V color index +1.045
Variable type BY Dra
Astrometry
A
Radial velocity (Rv)−5.1±0.2 km/s
Proper motion (μ) RA: −124.476±0.067 mas/yr
Dec.: −410.440±0.043 mas/yr
Parallax (π)70.857±0.019 mas
Distance46.03 ± 0.01 ly
(14.113 ± 0.004 pc)
Absolute magnitude (MV)+5.48
Orbit
PrimaryHR 7578 Aa
SecondaryHR 7578 Ab
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 7578 Aa
Mass0.87492±0.00032 M☉
Radius0.86±0.04 R☉
Luminosity0.35±0.02 L☉
Temperature4,820±200 K
Metallicity [Fe/H]0.28 dex
Rotational velocity (v sin i)2.0 km/s
HR 7578 Ab
Mass0.85978±0.00029 M☉
Radius0.81±0.04 R☉
Luminosity0.31±0.02 L☉
Temperature4,820±200 K
2MASS J19542064−2356398 (HR 7578 C)
Mass0.173±0.020 M☉
Radius0.204±0.004 R☉
Luminosity0.00304±0.00083 L☉
Surface gravity (log g)5.0570±0.0244 cgs
Temperature3,002±157 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, making it very faintly visible to the naked eye of an observer under a dark sky, far from any city. Parallax measurements by the Gaia spacecraft put the system at 46 light-years (14.1 parsecs) away, making this a nearby system.

The two main stars of HR 7578 are fairly old, older than the Pleiades but possibly younger than the Hyades. The stars are between 5×108 and 2×109 years old. Both are K-type main-sequence stars. 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.

In 1982, Francis C. Fekel and Willet I. Beavers suggested that HR 7578 might be a variable star, based on their spectroscopic observations. James T. Hooten and Douglas S. Hall confirmed that the star's brightness varies, in 1990. It was given its variable star designation, V4200 Sagittarii, in 1993. 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. There is another star that is separated about 40″ away and is 4.4 magnitudes fainter, but is not physically associated with HR 7578.

References

  1. ↑ "Light Curve". Hipparcos ESA. ESA. Retrieved 17 February 2022.
  2. 1 2 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
  3. 1 2 3 4 5 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.
  4. 1 2 3 4 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.
  5. 1 2 3 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.
  6. 1 2 3 4 5 6 7 8 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.
  7. 1 2 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  8. 1 2 3 4 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.
  9. ↑ Tokovinin, Andrei (2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series. 235 (1): 6. arXiv:1712.04750. Bibcode:2018ApJS..235....6T. doi:10.3847/1538-4365/aaa1a5.
  10. 1 2 3 4 5 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.
  11. 1 2 3 4 5 Stassun, Keivan G.; Oelkers, Ryan J.; Paegert, Martin; Torres, Guillermo; Pepper, Joshua; De Lee, Nathan; Collins, Kevin; Latham, David W.; Muirhead, Philip S.; Chittidi, Jay; Rojas-Ayala, Bárbara; Fleming, Scott W.; Rose, Mark E.; Tenenbaum, Peter; Ting, Eric B. (2019-10-01). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. ISSN 0004-6256. S2CID 166227927.
  12. ↑ Fekel, F. C.; Beavers, W. I. (December 1982). "HR 7578: a Possible Late-Type Eclipsing Binary and/or a BY Draconis Variable". Information Bulletin on Variable Stars. 2243: 1–2. Bibcode:1982IBVS.2243....1F.
  13. ↑ Hooten, James T.; Hall, Douglas S. (September 1990). "Photometry of 50 Suspected Variable Stars". Astrophysical Journal Supplement. 74: 225–247. Bibcode:1990ApJS...74..225H. doi:10.1086/191497.
  14. ↑ Kazarovets, E. V.; Samus, N. N.; Goranskij, V. P. (February 1993). "The 71st Name-List of Variable Stars". Information Bulletin on Variable Stars. 3840: 1–27. Bibcode:1993IBVS.3840....1K.