QX Andromedae

QX Andromedae (often abbreviated to QX And) is an eclipsing binary in the constellation Andromeda. It varies from a maximum apparent visual magnitude of 11.28 to a minimum of 11.50. Since it is impossible to specify the onset time of the eclipses, it is classified as a W Ursae Majoris variable star.[2] It is also observed as an X-ray source[8] and is a member of the open cluster NGC 752.[7]

QX Andromedae
Location of QX Andromedae (circled) in NGC 752
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension  01h 57m 57.7818s[1]
Declination +37° 48′ 22.4500″[1]
Apparent magnitude (V) 11.28 – 11.5 variable[2]
Characteristics
Spectral type F6[2]
Apparent magnitude (B) 11.77[3]
Apparent magnitude (R) 11.23[3]
Apparent magnitude (G) 11.2929[1]
Apparent magnitude (J) 10.393[4]
Apparent magnitude (H) 10.225[4]
Apparent magnitude (K) 10.163[4]
Variable type W UMa[2]
Astrometry
Radial velocity (Rv)11.70±0.27[5] km/s
Proper motion (μ) RA: 10.016±1.295 [1] mas/yr
Dec.: −11.926±0.281[1] mas/yr
Parallax (π)2.2376 ± 0.0676[1] mas
Distance1,460 ± 40 ly
(450 ± 10 pc)
Orbit[6]
Period (P)0.4121716 days
Semi-major axis (a)2.89±0.04 M☉
Inclination (i)54.6±0.2°
Details[6]
Primary
Mass1.47±0.05 M☉
Radius1.46±0.02 R☉
Surface gravity (log g)4.27±0.03 cgs
Temperature6,440 K
Age1.34±0.06[7] Gyr
Secondary
Mass0.45±0.02 M☉
Radius0.88±0.02 R☉
Surface gravity (log g)4.20±0.03 cgs
Temperature6420±20 K
Age1.34±0.06[7] Gyr
Other designations
2MASS J01575777+3748224, RX J015758.0+374820, TYC 2816-1950-1
Database references
SIMBADdata

System

As a whole, the QX Andromedae system emits light like a stellar blackbody, with a F6 spectral type.[2] The two stars in the system complete an orbit every 9.892 hours; they are so close that their envelopes are touching each other. Their temperature is similar, but they have different radius and mass.[6] Since they belong to an open cluster, the age of this system is equal to the cluster estimated age (1.34±0.06 billion years).[7]

Variability

The light curve of QX Andromedae shows almost equal eclipses; the primary eclipse occurs when the less massive star pass in front of the other one. The brightness variations are rather small for this system given the low orbital inclination of 55°.[6]

References
  1. 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.
  2. N. N. Samus; O. V. Durlevich; et al. "QX And database entry". Combined General Catalog of Variable Stars (2017 ed.). CDS. Retrieved 2018-11-12.
  3. Norton, A. J.; Wheatley, P. J.; West, R. G.; Haswell, C. A.; Street, R. A.; Collier Cameron, A.; Christian, D. J.; Clarkson, W. I.; Enoch, B.; Gallaway, M.; Hellier, C.; Horne, K.; Irwin, J.; Kane, S. R.; Lister, T. A.; Nicholas, J. P.; Parley, N.; Pollacco, D.; Ryans, R.; Skillen, I.; Wilson, D. M. (2007). "New periodic variable stars coincident with ROSAT sources discovered using SuperWASP". Astronomy and Astrophysics. 467 (2): 785. arXiv:astro-ph/0702631. Bibcode:2007A&A...467..785N. doi:10.1051/0004-6361:20077084.
  4. Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; et al. (June 2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues (2246): II/246. Bibcode:2003yCat.2246....0C.
  5. Bilir, S.; Karataș, Y.; Demircan, O.; Eker, Z. (2005). "Kinematics of W Ursae Majoris type binaries and evidence of the two types of formation". Monthly Notices of the Royal Astronomical Society. 357 (2): 497–517. Bibcode:2005MNRAS.357..497B. doi:10.1111/j.1365-2966.2005.08609.x.
  6. Djurašević, G.; Yılmaz, M.; Baștürk, Ö.; Kılıçoğlu, T.; Latković, O.; Çalıșkan, Ş.; Christian, D. J.; Enoch, B.; Gallaway, M.; Hellier, C.; Horne, K.; Irwin, J.; Kane, S. R.; Lister, T. A.; Nicholas, J. P.; Parley, N.; Pollacco, D.; Ryans, R.; Skillen, I.; Wilson, D. M. (2011). "Physical parameters of close binaries QX Andromedae, RW Comae Berenices, MR Delphini, and BD +079° 3142". Astronomy and Astrophysics. 525: A66. arXiv:1011.3677. Bibcode:2011A&A...525A..66D. doi:10.1051/0004-6361/201014895.
  7. Agüeros, M. A.; Bowsher, E. C.; Bochanski, J. J.; Cargile, P. A.; Covey, K. R.; Douglas, S. T.; Kraus, A.; Kundert, A.; Law, N. M.; Ahmadi, A.; Arce, H. G. (July 2018). "A New Look at an Old Cluster: The Membership, Rotation, and Magnetic Activity of Low-mass Stars in the 1.3 Gyr Old Open Cluster NGC 752". The Astrophysical Journal. 862 (1): 33. arXiv:1804.02016. Bibcode:2018ApJ...862...33A. doi:10.3847/1538-4357/aac6ed.
  8. Belloni, T.; Verbunt, F. (January 1996). "Soft X-rays from the intermediate-age open cluster NGC 752". Astronomy and Astrophysics. 305: 806. Bibcode:1996A&A...305..806B.
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