RW Aurigae

RW Aurigae

Light curves for RW Aurigae derived from photographic plate data, adapted from Beck and Simon (2007)[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Auriga
RW Aurigae A
Right ascension	05^h 07^m 49.4561^s[2]
Declination	+30° 24′ 04.7772″[2]
Apparent magnitude (V)	9.6
RW Aurigae B
Right ascension	05^h 07^m 49.5652^s[3]
Declination	30° 24′ 05.1361″[3]
Characteristics
RW Aurigae A
Spectral type	K1-K3[4]
Apparent magnitude (G)	12.2048±0.0093[5]
Variable type	T Tau
RW Aurigae B
Spectral type	K5[4]
Apparent magnitude (G)	13.3177±0.0653[6]
Astrometry
A
Proper motion (μ)	RA: 2.747[2] mas/yr Dec.: -27.558[2] mas/yr
Parallax (π)	6.1157 ± 0.0665 mas[5]
Distance	533 ± 6 ly (164 ± 2 pc)
B
Proper motion (μ)	RA: 4.238[3] mas/yr Dec.: -24.996[3] mas/yr
Parallax (π)	6.5835 ± 0.9023 mas[6]
Distance	approx. 500 ly (approx. 150 pc)
Position (relative to RW Aurigae A)[7]
Component	RW Aurigae B
Epoch of observation	4/6/2007
Angular distance	1.448±0.005″
Position angle	255.9±0.3°
Projected separation	237 AU
Details
A
Mass	1.34±0.18[4] M☉
Luminosity	0.59[4] L☉
Temperature	5082[4] K
Rotation	5.6 d.[8]
Age	3±1[9] Myr
B
Mass	0.9[10] M☉
Radius	1.5[9] R☉
Luminosity	0.6[9] L☉
Temperature	4150±50[9] K
Age	3±1[9] Myr
Other designations
BD+30 792, HD 240764, HIP 23873, TYC 2389-955-1, GSC 02389-00955, 2MASS J05074953+3024050
RW Aurigae A: Gaia DR2 156430822114424576
RW Aurigae B: Gaia DR2 156430817820015232
Database references
SIMBAD	data

RW Aurigae is a young binary system in the constellation of Auriga about 530 light years away, belonging to the Taurus-Auriga association of the Taurus Molecular Cloud. RW Aurigae B was discovered in 1944.^[7]

System

The two stars of the RW Aurigae system are separated by 1.448″, equivalent to 237 AU at the distance of RW Aurigae. The primary is a pre-main sequence star with a mass of 1.4 M_☉, while the secondary has a mass of 0.9 M_☉. These are loosely bound,^[9] and their orbital trajectory is nearly parabolic,^[10] with an orbital period of 1000−1500 years as evidenced by the structure of the ejected dust jets. The star system's orbit is retrograde compared to the rotation direction of the disk orbiting the primary star.^[7] RW Aurigae A is also suspected to be a close binary since 1999.^[11]

Properties

Both members of the binary are medium-mass objects still contracting towards the main sequence and accreting mass, RW Aurigae A at the rate of 0.1M_☉/Myr,^[10] and RW Aurigae B at the rate of 0.005M_☉/Myr.^[9] Their ages are equal to 3±1 million years.^[9]

The binary is surrounded by a complex accretion structure, containing a circumbinary shell, spiral arms, bow shocks and protoplanetary disks. RW Aur A is producing complex bipolar jets extending as far as 46 thousand AU from the star.^[7] Its protoplanetary disk is inclined to the line of sight by 45-60 degrees.^[12] It is not known if planetary formation in the disk has been arrested by stellar encounter or accelerated, as a wide range of debris sizes, consistent with both a collision cascade and ongoing planetesimal formation were detected.^[13] However, new work published in the 2018 - 2022 time period has shown strong evidence for the stochastic destruction of a large asteroid (approx. Vesta sized) differentiated planetesimal's Fe (iron) core at the inner edge of RW Aur A's accretion disk and the funneling of this material into the protostar's atmosphere and outflow jets. This implies both the creation of large asteroid-like bodies in far-out, cooler regions of the accretion disk and their migration into its innermost regions where they undergo catastrophic high energy collisions.^[14][15][16]

Variability

In 1906, Vitold Tserasky discovered that BD+30 792 is a variable star.^[17] It was subsequently given the variable star designation RW Aurigae. RW Aurigae A varies in brightness. It is a T Tauri variable, and a prototype for the eponymous class of RW Aurigae variables,^[18] exhibiting irregular dips in its light curve due to the rapidly changing geometry of the protoplanetary disk, disturbed by the periastron passage of RW Aurigae B.^[10] A previous periastron passage happened about 400 years ago.^[9] The long-lasting brightness dips in 2010-2011 and 2014-2016 reduced the star's brightness to magnitude 12.5,^[12] before recovering to visual magnitude 10.5-11.0 by August 2016.^[19]

The companion star is itself a variable of UX Orionis type, exhibiting both chaotic variations of brightness and short (less than one day) brightness dips due to continuing accretion and the inhomogeneity of the protoplanetary disk.^[9]

See also

• FU Tauri

References

1. Beck, Tracy L.; Simon, Mona (December 2007). "The variability of T Tauri, RY Tauri, and RW Aurigae from 1899 to 1952". The Astronomical Journal. 122: 413–417. Bibcode:1990VeSon..10..442C. doi:10.1086/321133. S2CID 14520286.
2. "V* RW Aur A", SIMBAD, Centre de données astronomiques de Strasbourg
3. "V* RW Aur B", SIMBAD, Centre de données astronomiques de Strasbourg
4. Skinner, Stephen L.; Guedel, Manuel (2014). "Chandra Resolves the T Tauri Binary System RW Aur". arXiv:1404.2631 [astro-ph.SR].
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.
6. 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.
7. Bisikalo, D. V.; Dodin, A. V.; Kaigorodov, P. V.; Lamzin, S. A.; Malogolovets, E. V.; Fateeva, A. M. (2012). "Reverse rotation of the accretion disk in RW Aur A: Observations and a physical model". Astronomy Reports. 56 (9): 686–692. arXiv:1207.4022. Bibcode:2012ARep...56..686B. doi:10.1134/S1063772912090028. S2CID 18483219.
8. Dodin, A. V.; Lamzin, S. A.; Chountonov, G. A. (2011). "Magnetic field of young star RW Aur". Astronomy Letters. 38 (3): 167–179. arXiv:1111.2309. doi:10.1134/S1063773712020028. S2CID 117871951.
9. Dodin, A.; Lamzin, S.; Petrov, P.; Safonov, B.; Takami, M.; Tatarnikov, A. (2020). "RW Aur B: A modest UX Ori-type companion of the famous primary". Monthly Notices of the Royal Astronomical Society. 497 (4): 4322–4332. arXiv:2007.12559. doi:10.1093/mnras/staa2206.
10. Cuello, Nicolás; Louvet, Fabien; Mentiplay, Daniel; Pinte, Christophe; Price, Daniel J.; Winter, Andrew J.; Nealon, Rebecca; Ménard, François; Lodato, Giuseppe; Dipierro, Giovanni; Christiaens, Valentin; Montesinos, Matías; Cuadra, Jorge; Laibe, Guillaume; Cieza, Lucas; Dong, Ruobing; Alexander, Richard (2020). "Flybys in protoplanetary discs – II. Observational signatures". Monthly Notices of the Royal Astronomical Society. 491: 504–514. arXiv:1910.06822. doi:10.1093/mnras/stz2938.
11. Gahm, G. F.; Petrov, P. P.; Duemmler, R.; Gameiro, J. F.; Lago, M. T. V. T. (1999). "RW Aur A, a close binary?". Astronomy and Astrophysics. 352: L95. Bibcode:1999A&A...352L..95G.
12. Bozhinova, I.; Scholz, A.; Costigan, G.; Lux, O.; Davis, C. J.; Ray, T.; Boardman, N. F.; Hay, K. L.; Hewlett, T.; Hodosán, G.; Morton, B. (2016). "The disappearing act: A dusty wind eclipsing RW Aur". Monthly Notices of the Royal Astronomical Society. 463 (4): 4459–4468. arXiv:1609.05667. doi:10.1093/mnras/stw2327.
13. Rodriguez, Joseph E.; Reed, Phillip A.; Siverd, Robert J.; et al. (2016). "Recurring Occultations of Rw Aurigae by Coagulated Dust in the Tidally Disrupted Circumstellar Disk". The Astronomical Journal. 151 (2): 29. arXiv:1512.03745. Bibcode:2016AJ....151...29R. doi:10.3847/0004-6256/151/2/29. S2CID 118540299.
14. Günther, H.M.; Birnstiel, T.; Huenemoerder, D.P.; et al. (2018). "Optical dimming of RW Aur associated with an iron rich corona and exceptionally high absorbing column density". The Astronomical Journal. 156 (2): 56. arXiv:1807.06995. Bibcode:2018AJ....156...56G. doi:10.3847/1538-3881/aac9bd. S2CID 119488564.
15. Takami, M.; Beck, T.L.; Schneider, P.C.; et al. (2020). "Possible Time Correlation Between Jet Ejection and Mass Accretion for RW Aur A". The Astrophysical Journal. 901 (1): 24. arXiv:2007.15848v1. Bibcode:2020ApJ...901...24T. doi:10.3847/1538-4357/abab98. S2CID 220920124.
16. Lisse, C.M.; Sitko, M.L.; Wolk, S.J.; et al. (2022). "RW Aur A: SpeX Spectral Evidence for Differentiated Planetesimal Formation, Migration, and Destruction in an 3 Myr Old Excited CTTS System". The Astrophysical Journal. 928 (2): 189. arXiv:2201.10465. Bibcode:2022ApJ...928..189L. doi:10.3847/1538-4357/ac51e0. S2CID 246275790.
17. Ceraski, W. (March 1906). "Deux nouvelles variables". Astronomische Nachrichten. 170 (21): 339. Bibcode:1906AN....170..339C. doi:10.1002/asna.19051702103. Retrieved 30 November 2024.
18. Herbig, G. H. (1954). "The spectra of variable stars of the RW Aurigae type". IAU Transactions. 8: 805. Bibcode:1954IAUT....8..805H.
19. Scholz, Aleks; Bozhinova, Inna; Lux, Oliver; Pannicke, Anna; Mugrauer, Markus (2016). "Re-brightening of the young star RW Aur: The end of the second deep eclipse". The Astronomer's Telegram. 9428: 1. Bibcode:2016ATel.9428....1S.