4 Draconis, also known as HR 4765 and CQ Draconis, is a star about 570 light years from the Earth, in the constellation Draco.[3] It is a 5th magnitude star, so it will be faintly visible to the naked eye of an observer far from city lights.[3] It is a variable star, whose brightness varies slightly from 4.90 to 5.12 over a period of 4.66 years.[4]
 Light curves for CQ Draconis, adapted from Skopal et al. (1992)[1] The brightening seen (most clearly in the ultraviolet) after June 1990 occurred shortly after the periastron passage.[2] | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Draco |
| Right ascension | 12h 30m 06.66200s[3] |
| Declination | +69° 12′ 03.9742″[3] |
| Apparent magnitude (V) | 4.90 - 5.12[4] |
| Characteristics | |
| Spectral type | M3+ IIIa[5] |
| Variable type | Z Andromedae[4] |
| Astrometry | |
| Radial velocity (Rv) | −15[6] km/s |
| Proper motion (μ) | RA: −57.311±0.214[3] mas/yr Dec.: −50.365±0.219[3] mas/yr |
| Parallax (π) | 5.7233 ± 0.1880 mas[3] |
| Distance | 570 ± 20 ly (175 ± 6 pc) |
| Absolute magnitude (MV) | −1.37[7] |
| Orbit[8] | |
| Primary | 4 Draconis A (red giant) |
| Companion | 4 Draconis B |
| Period (P) | 1,703±3 d |
| Semi-major axis (a) | 82±4 Gm ( a⋅sin(i) ) |
| Eccentricity (e) | 0.30±0.05 |
| Periastron epoch (T) | 2442868.5 |
| Argument of periastron (ω) (primary) | 244±9° |
| Semi-amplitude (K1) (primary) | 3.67±0.19 km/s |
| Details | |
| red giant | |
| Mass | 1.64±0.2[9] M☉ |
| Radius | 111.0+9.30 −11.2[9] R☉ |
| Luminosity | 2,122±419[9] L☉ |
| Surface gravity (log g) | 1.24[9] cgs |
| Temperature | 3,718±69[9] K |
| Age | 1.97±0.57[9] Gyr |
| white dwarf | |
| Mass | ~0.8[10] M☉ |
| Temperature | 20,000±3,000[10] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
In 1967, Olin Eggen discovered that 4 Draconis is a variable star, during a multicolor photometric survey of red stars.[12] In 1973 it was given the variable star designation CQ Draconis.[13]
Until the year 1985, 4 Draconis was thought to be a normal red giant star. In 1985, Dieter Reimers announced that the International Ultraviolet Explorer had detected a hot companion to the red giant, which itself appeared to be a binary cataclysmic variable star, making the complete system a triple star.[14] However a 2003 study by Peter Wheatley et al., who examined ROSAT X-ray data for the star, concluded that the hot companion was more apt to be a single white dwarf, rather than a binary, and that the white dwarf is accreting material from the red giant.[15] There does not yet appear to be a consensus about the multiplicity; some later studies consider 4 Draconis to be a binary,[16][17] and some a triple.[18][10]
In 1987, Alexander Brown announced that 6 cm wavelength radio emission had been detected by the Very Large Array. The strength of the radio emission was variable on a timescale of weeks to months.[19]
It is possible that an outburst of 4 Draconis was the "guest star" reported by Chinese astronomers in the year 369 CE, in the constellation Zigong.[20]
References
edit- ^ Skopal, A.; Hric, L.; Urban, Z.; Pigulski, A.; Blanco, C.; Papousek, J.; Hanzl, D.; Agerer, F.; Niarchos, P.; Rovithis-Livaniou, H.; Rovithis, P.; Tsvetkova, K.; Semkov, E.; Velic, Z.; Michalek, F.; Komacka, L.; Schweitzer, E.; Korth, S. (July 1992). "Photometry of symbiotic stars - an international campaign. III. Z And, EG And, R Aqr, UV Aur, TX CVn, T CrB, BF Cyg, CH Cyg, CI Cyg, V 1016 Cyg, V 1329 Cyg, AG Dra, CQ DRA (4 Dra), YY Her, V 443 Her, SS Lep, RS Oph, AG Peg, AX Per, HM Sge, FG Ser (AS 296), PU Vul". Contributions of the Astronomical Observatory Skalnate Pleso. 22: 131–172. Bibcode:1992CoSka..22..131S. Retrieved 26 February 2023.
- ^ Hric, L.; Urban, Z. (November 1991). "The Symbiotic-Like/Cataclysmic Triple System 4 Dra (= CQ Dra): Detection of a Post-Periastron Passage Brightening" (PDF). Information Bulletin on Variable Stars. 3683: 1. Bibcode:1991IBVS.3683....1H. Retrieved 28 February 2023.
- ^ a b c d e f g Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c "CQ Dra". The International Variable Star Index. AAVSO. Retrieved 26 February 2023.
- ^ Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". The Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
- ^ Famaey, B.; Pourbaix, D.; Frankowski, A.; van Eck, S.; Mayor, M.; Udry, S.; Jorissen, A. (May 2009). "Spectroscopic binaries among Hipparcos M giants,. I. Data, orbits, and intrinsic variations". Astronomy and Astrophysics. 498 (2): 627–640. arXiv:0901.0934. Bibcode:2009A&A...498..627F. doi:10.1051/0004-6361/200810698.
- ^ 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. S2CID 119257644.
- ^ Reimers, D.; Griffin, R. F.; Brown, A. (March 1988). "4 Draconis : a unique triple system containing an M3 giant and a cataclysmic binary". Astronomy and Astrophysics. 193: 180–184. Bibcode:1988A&A...193..180R. Retrieved 28 February 2023.
- ^ a b c d e f Baines, Ellyn K.; Armstrong, J. Thomas; Schmitt, Henrique R.; Zavala, R. T.; Benson, James A.; Hutter, Donald J.; Tycner, Christopher; van Belle, Gerard T. (2017). "Fundamental parameters of 87 stars from the Navy Precision Optical Interferometer". The Astronomical Journal. 155 (1): 16. arXiv:1712.08109. Bibcode:2018AJ....155...30B. doi:10.3847/1538-3881/aa9d8b. S2CID 119427037.
- ^ a b c Sion, Edward M.; Godon, Patrick; Mikolajewska, Joanna; Sabra, Bassem; Kolobow, Craig (April 2017). "FUSE Spectroscopy of the Accreting Hot Components in Symbiotic Variables". The Astronomical Journal. 153 (4): 160. arXiv:1702.07341. Bibcode:2017AJ....153..160S. doi:10.3847/1538-3881/aa62a9. PMC 5810147. PMID 29456255.
- ^ "4 Dra -- Spectroscopic Binary". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-02-26.
- ^ Eggen, O. J. (September 1967). "Narrow and broad band photometry of red stars : I. Northern giants". Astrophysical Journal Supplement Series. 14: 307–358. Bibcode:1967ApJS...14..307E. doi:10.1086/190158. Retrieved 27 February 2023.
- ^ Kukarkin, B. V.; Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (October 1973). "59th Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 834: 1. Bibcode:1973IBVS..834....1K. Retrieved 27 February 2023.
- ^ Reimers, D. (January 1985). "Discovery of a cataclysmic variable type companion of the M3 III giant 4 DRA with IUE". Astronomy and Astrophysics. 142: L16–L18. Bibcode:1985A&A...142L..16R. Retrieved 27 February 2023.
- ^ Wheatley, Peter J.; Mukai, Koji; de Martino, Domitilla (December 2003). "X-ray observations of 4 Draconis: symbiotic binary or cataclysmic triple?". Monthly Notices of the Royal Astronomical Society. 346 (3): 855–860. arXiv:astro-ph/0309410. Bibcode:2003MNRAS.346..855W. doi:10.1111/j.1365-2966.2003.07149.x.
- ^ Skopal, A. (August 2005). "Accretion-powered symbiotic binaries: EG And and CQ Dra" (PDF). The Astrophysics of Cataclysmic Variables and Related Objects, Proceedings of ASP Conference. 330: 463–464. Bibcode:2005ASPC..330..463S. Retrieved 28 February 2023.
- ^ Nuñez, N. E.; Nelson, T.; Mukai, K.; Sokoloski, J. L.; Luna, G. J. M. (June 2016). "Symbiotic Stars in X-Rays. III. Suzaku Observations". The Astrophysical Journal. 824 (1): 23. arXiv:1604.05980. Bibcode:2016ApJ...824...23N. doi:10.3847/0004-637X/824/1/23.
- ^ Di Stefano, R. (April 2020). "Mass from a third star: transformations of close compact-object binaries within hierarchical triples". Monthly Notices of the Royal Astronomical Society. 493 (2): 1855–1873. arXiv:1805.09338. Bibcode:2020MNRAS.493.1855D. doi:10.1093/mnras/staa220. Retrieved 28 February 2023.
- ^ Brown, Alexander (January 1987). "Variable Radio Emission from the 4 Draconis System". Astrophysical Journal Letters. 312: L51–L53. Bibcode:1987ApJ...312L..51B. doi:10.1086/184818. Retrieved 27 February 2023.
- ^ Hoffmann, Susanne M.; Vogt, Nikolaus (September 2020). "A search for the modern counterparts of the Far Eastern guest stars 369 CE, 386 CE and 393 CE". Monthly Notices of the Royal Astronomical Society. 497 (2): 1419–1433. arXiv:2007.01013. Bibcode:2020MNRAS.497.1419H. doi:10.1093/mnras/staa1970.