Astronomy:QR Andromedae
 The visual band light curve of QR Andromedae (adapted from Matsumoto (1996)), The phase is with respect to the 15.85 hour orbital period.[1] | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 00h 19m 49.9253s[2] |
| Declination | +21° 56′ 52.1666″[2] |
| Apparent magnitude (V) | 12.16 – 13.07 variable[3] |
| Characteristics | |
| Spectral type | pec(e)[3] |
| Apparent magnitude (B) | 12.38[4] |
| Apparent magnitude (R) | 11.86[4] |
| Apparent magnitude (G) | 12.2395[2] |
| Apparent magnitude (J) | 12.432[5] |
| Apparent magnitude (H) | 12.295[5] |
| Apparent magnitude (K) | 12.092[5] |
| Variable type | Algol[3] |
| Astrometry | |
| Proper motion (μ) | RA: 18.469±0.071 [2] mas/yr Dec.: −5.529±0.079[2] mas/yr |
| Parallax (π) | 0.4993 ± 0.0452[2] mas |
| Distance | 6,500 ± 600 ly (2,000 ± 200 pc) |
| Orbit | |
| Period (P) | 0.6604 days[4] |
| Semi-amplitude (K1) (primary) | 61.8±4.4[6] km/s |
| Other designations | |
2MASS J00194992+2156521, AAVSO 0014+21 | |
| Database references | |
| SIMBAD | data |
QR Andromedae (often abbreviated to QR And) is an eclipsing binary star in the constellation Andromeda. Its maximum apparent visual magnitude is 12.16, but its light curve shows clearly eclipsing events where its brightness can drop to a magnitude of 13.07.[6] This leads to its classification as an Algol variable star.[3]
Spectrum
The optical spectrum of QR Andromedae is not of a typical stellar blackbody, but is peculiar with many emission lines,[3] the strongest being the HeII line. Balmer series and OVI lines are also present. It was also one of the super soft X-ray sources discovered by ROSAT satellite, one of the few source of this kind observed so far in the Milky Way.[6]
System
It is now commonly accepted that super soft X-ray sources are white dwarfs that are burning matter with nuclear fusion on their surfaces, sustained by a high accretion rate of matter coming from a companion star. QR Andromedae is the nearest and brightest of those sources, and it has an orbital period of 15.85 hours. The companion star has a mass between 0.3 – 0.5 M☉ and should be a remnant of a more massive evolved star that is filling its Roche lobe.[6]
Variability
Photographic plates from the Harvard College and Sonneberg observatories have recorded QR Andromedae's brightness history since the late 19th century. Jochen Greiner and Wolfgang Wenzel constructed a 100 year light curve for the star. They found that the light curve exhibited brightness changes of up to one magnitude, on a variety of timescales. They proposed that this was the result of unstable mass transfers onto the white dwarf, triggering sporadic hydrogen burning.[7]
Eclipses in the light curve of QR Andromedae are not symmetrical: the ingress is more gradual than the egress. The secondary minimum is variable in occurring phase and depth, meaning that the occultation of the secondary star happens behind a variable part of the disk. Out of the eclipses, light flickering can be clearly seen, and in some observations a periodicity arises.[6]
References
- ↑ Matsumoto, Katsura (1 December 1996). "BVRI Photometric Light Curves of the Galactic Supersoft X-Ray Source RX J0019.8+2156". Publications of the Astronomical Society of Japan 48 (6): 827–831. doi:10.1093/pasj/48.6.827. https://academic.oup.com/pasj/article/48/6/827/2948837. Retrieved 5 October 2021.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 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.
- ↑ 3.0 3.1 3.2 3.3 3.4 "QR And database entry". Combined General Catalog of Variable Stars. CDS. http://webviz.u-strasbg.fr/viz-bin/VizieR-S?V*%20QR%20And.
- ↑ 4.0 4.1 4.2 Norton, A. J.; Wheatley, P. J.; West, R. G.; Haswell, C. A.; Street, R. A.; Collier Cameron, A.; Christian, D. J.; Clarkson, W. I. et al. (2007). "New periodic variable stars coincident with ROSAT sources discovered using SuperWASP". Astronomy and Astrophysics 467 (2): 785. doi:10.1051/0004-6361:20077084. Bibcode: 2007A&A...467..785N.
- ↑ 5.0 5.1 5.2 Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E. et al. (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. http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=II/246.
- ↑ 6.0 6.1 6.2 6.3 6.4 McGrath, T. K.; Schmidtke, P. C.; Cowley, A. P.; Ponder, A. L.; Wagner, R. M. (2001). "Simultaneous Photometry and Spectroscopy of the Supersoft X-Ray Source RX J0019.8+2156 (QR Andromedae)". The Astronomical Journal 122 (3): 1578–1585. doi:10.1086/322109. Bibcode: 2001AJ....122.1578M.
- ↑ Greiner, J.; Wenzel, W. (February 1995). "Optical variability of the supersoft source RXJ0019.8+2156". Astronomy and Astrophysics 294: L5–L8. Bibcode: 1995A&A...294L...5G. https://ui.adsabs.harvard.edu/abs/1995A&A...294L...5G. Retrieved 9 February 2023.
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