Astronomy:HR 7578
| Characteristics | |
|---|---|
| A | |
| Spectral type | K3 V + K3 V[2] + M5[3] |
| U−B color index | +0.915[4] |
| B−V color index | +1.045[4] |
| Variable type | BY Dra[5] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | −5.1±0.2[6] km/s |
| Proper motion (μ) | RA: −124.476±0.067[7] mas/yr Dec.: −410.440±0.043[7] mas/yr |
| Parallax (π) | 70.857 ± 0.019[3] mas |
| Distance | 46.03 ± 0.01 ly (14.113 ± 0.004 pc) |
| Absolute magnitude (MV) | +5.48[8] |
| Orbit[9][3] | |
| Primary | HR 7578 Aa |
| Companion | HR 7578 Ab |
| Period (P) | 46.81614±0.00003 d |
| Semi-major axis (a) | 0.3054±0.0001 astronomical unit|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 | |
| Mass | 0.87492±0.00032[3] M☉ |
| Radius | 0.86±0.04[10] R☉ |
| Luminosity | 0.35±0.02[10] L☉ |
| Temperature | 4,820±200[3] K |
| Metallicity [Fe/H] | 0.28[3] dex |
| Rotational velocity (v sin i) | 2.0[2] km/s |
| HR 7578 Ab | |
| Mass | 0.85978±0.00029[3] M☉ |
| Radius | 0.81±0.04[10] R☉ |
| Luminosity | 0.31±0.02[10] L☉ |
| Temperature | 4,820±200[3] K |
| 2MASS J19542064−2356398 (HR 7578 C) | |
| Mass | 0.173±0.020[11] M☉ |
| Radius | 0.204±0.004[11] R☉ |
| Luminosity | 0.00304±0.00083[11] L☉ |
| Surface gravity (log g) | 5.0570±0.0244[11] cgs |
| Temperature | 3,002±157[11] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
HR 7578 (also known as V4200 Sagittarii) is a triple star system in the constellation of Sagittarius. Their combined apparent magnitude is 6.18,[5] 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.[7]
The two main 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.[2] 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]
In 1982, Francis C. Fekel and Willet I. Beavers suggested that HR 7578 might be a variable star, based on their spectroscopic observations.[12] James T. Hooten and Douglas S. Hall confirmed that the star's brightness varies, in 1990.[13] It was given its variable star designation, V4200 Sagittarii, in 1993.[14] 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.[5] There is another star that is separated about 40″ away and is 4.4 magnitudes fainter, but is not physically associated with HR 7578.[10]
References
- ↑ "Light Curve". ESA. https://www.cosmos.esa.int/web/hipparcos/java-tools/light-curve.
- ↑ 2.0 2.1 2.2 Pasquini, L.; Cortés, C.; Lombardi, M.; Monaco, L.; Leão, I. C.; Delabre, B. (2015). "Tachoastrometry: Astrometry with radial velocities". Astronomy & Astrophysics 574: A76. doi:10.1051/0004-6361/201424882. Bibcode: 2015A&A...574A..76P.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 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. doi:10.1051/0004-6361/202245712. ISSN 0004-6361. Bibcode: 2023A&A...672A.119G.
- ↑ 4.0 4.1 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode: 1986EgUBV........0M.
- ↑ 5.0 5.1 5.2 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. doi:10.1093/mnras/stt1953. Bibcode: 2014MNRAS.437..879C.
- ↑ 6.0 6.1 6.2 6.3 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. doi:10.1086/160905. Bibcode: 1983ApJ...267..682F.
- ↑ 7.0 7.1 7.2 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A XHIP record for this object at VizieR.
- ↑ Tokovinin, Andrei (2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series 235 (1): 6. doi:10.3847/1538-4365/aaa1a5. Bibcode: 2018ApJS..235....6T.
- ↑ 10.0 10.1 10.2 10.3 10.4 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. doi:10.3847/1538-3881/aa816e. Bibcode: 2017AJ....154..120F.
- ↑ 11.0 11.1 11.2 11.3 11.4 Stassun, Keivan G.; Oelkers, Ryan J.; Paegert, Martin; Torres, Guillermo; Pepper, Joshua; De Lee, Nathan; Collins, Kevin; Latham, David W. et al. (2019-10-01). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. ISSN 0004-6256. Bibcode: 2019AJ....158..138S.
- ↑ 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.
- ↑ Hooten, James T.; Hall, Douglas S. (September 1990). "Photometry of 50 Suspected Variable Stars". Astrophysical Journal Supplement 74: 225–247. doi:10.1086/191497. Bibcode: 1990ApJS...74..225H.
- ↑ 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.
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