AB Aurigae

ALMA image of the dust ring (red) and gaseous spirals (blue) of the circumstellar disk AB Aurigae reveal gaseous spiral arms inside a wide dust gap, providing a hint of planet formation.
Credit: ALMA (ESO/NAOJ/NRAO)/Tang et al.
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension 04h 55m 45.84600s[1]
Declination +30° 33′ 04.2933″[1]
Apparent magnitude (V) 7.05[2]
Characteristics
Evolutionary stage Pre-main-sequence[3]
Spectral type A0Ve[4]
U−B color index +0.04[5]
B−V color index +0.11[5]
Variable type INA (Herbig Ae)[3][6]
Astrometry
Radial velocity (Rv)+8.9±0.9[7] km/s
Proper motion (μ) RA: +3.926[1] mas/yr
Dec.: –24.112[1] mas/yr
Parallax (π)6.1400 ± 0.0571 mas[1]
Distance531 ± 5 ly
(163 ± 2 pc)
Details
Mass2.4±0.2[8] M☉
Radius2.5[9] R☉
Luminosity~38[8] L☉
Temperature9,772[10] K
Age4±1[8] Myr
Other designations
AB Aur, BD+30° 741, HD 31293, HIP 22910, SAO 57506[11]
Database references
SIMBADdata

AB Aurigae is a young Herbig Ae star[3] in the Auriga constellation. It is located at a distance of approximately 531 light years from the Sun based on stellar parallax.[1] This pre-main-sequence star has a stellar classification of A0Ve,[4] matching an A-type main-sequence star with emission lines in the spectrum. It has 2.4 times the mass of the Sun and is radiating 38[8] times the Sun's luminosity from its photosphere at an effective temperature of 9,772 K.[10] The radio emission from the system suggests the presence of a thermal jet originating from the star with a velocity of 300 km s−1. This is causing an estimated mass loss of 1.7×10−8 M☉ yr−1.[8]

This star is known for hosting a dust disk that may harbour a condensing planet or brown dwarf. The star could host a possible substellar companion in wide orbit. The star is part of the young Taurus-Auriga association,[4] which is located in the Taurus Molecular Cloud.[12] The star itself may recently have encountered a dense cloudlet, which disrupted its debris disk and produced an additional reflection nebula.[13]

Planetary system

In 2017 scientists used the Atacama Large Millimeter/submillimeter Array (ALMA) to take an image of the protoplanetary disk around AB Aurigae. The image showed a dusty disk which has a radius of about 120 astronomical units and a distinct "gap". Inside this gap gaseous spiral arms are detected in CO.[14][3]

Oppenheimer et al. (2008)[15] observed an annulus feature in AB Aurigae's dust disk between 43 and 302 AU from the star, a region never seen before. An azimuthal gap in an annulus of dust at a radius of 102 AU would suggest the formation of at least one small body at an orbital distance of nearly 100 AU. Such an object could turn out to be either a massive planetary companion or more likely a brown dwarf companion, in both cases located at nearly 100 AU from the bright star. So far the object is unconfirmed.

Observations with ALMA found two gaseous spiral arms inside the disk. These are best explained by an unseen planet with a semimajor axis of about 60–80 au. An additional planet with a semimajor axis of 30 au and with a large pitch angle compared to the disk (likely higher inclination) could explain the emptiness of the inner dusty disk.[3] The outer planet was still not detected as in 2022, putting an upper limit on is mass at 3–4 MJ, inconsistent with the spiral structures observed in the disk.[16] The planet-like clump observed in April 2022 at projected separation 93 AU from star, may be either an accretion disk around newly formed planet or the unstable disk region currently transforming into the planet.[17] The planet observation was confirmed in July 2022.[18]

The AB Aurigae planetary system[15]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(years)		 Eccentricity Inclination Radius
protoplanetary disk 43–430[13] AU — —
b[17] 9–12[17] MJ 93[17]  ? 0.19–0.60 27.1–58.2° 2.75 RJ

References

  1. 1 2 3 4 5 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.
  2. ↑ Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. 1 2 3 4 5 Tang, Ya-Wen; et al. (May 2017). "Planet Formation in AB Aurigae: Imaging of the Inner Gaseous Spirals Observed inside the Dust Cavity". The Astrophysical Journal. 840 (1): 32. arXiv:1704.02699. Bibcode:2017ApJ...840...32T. doi:10.3847/1538-4357/aa6af7. ISSN 0004-637X. S2CID 119351517.
  4. 1 2 3 Mooley, Kunal; et al. (July 2013). "B- and A-type Stars in the Taurus-Auriga Star-forming Region". The Astrophysical Journal. 771 (2): 24. arXiv:1306.0598. Bibcode:2013ApJ...771..110M. doi:10.1088/0004-637X/771/2/110. S2CID 2176170. 110.
  5. 1 2 Nicolet, B. (1964). "Catalogue of homogeneous data in the UBV photoelectric photometric system". Astronomy and Astrophysics Supplement Series. 34: 1–49. Bibcode:1978A&AS...34....1N.
  6. ↑ Samus', N. N.; et al. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. ISSN 1063-7729. S2CID 125853869.
  7. ↑ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  8. 1 2 3 4 5 Rodríguez, Luis F.; et al. (September 2014). "An Ionized Outflow from AB Aur, a Herbig Ae Star with a Transitional Disk". The Astrophysical Journal Letters. 793 (1): 4. arXiv:1408.7068. Bibcode:2014ApJ...793L..21R. doi:10.1088/2041-8205/793/1/L21. S2CID 118640915. L21.
  9. ↑ Li, Dan; et al. (2016). "An Ordered Magnetic Field in the Protoplanetary Disk of AB Aur Revealed by Mid-infrared Polarimetry". The Astrophysical Journal. 832 (1): 18. arXiv:1609.02493. Bibcode:2016ApJ...832...18L. doi:10.3847/0004-637X/832/1/18. S2CID 118475064.
  10. 1 2 Tannirkulam, A.; et al. (2008). "A Tale of Two Herbig Ae Stars, MWC 275 and AB Aurigae: Comprehensive Models for Spectral Energy Distribution and Interferometry". The Astrophysical Journal. 689 (1): 513–531. arXiv:0808.1728. Bibcode:2008ApJ...689..513T. doi:10.1086/592346. S2CID 45548.
  11. ↑ "AB Aur". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-03-05.
  12. ↑ Gagné, Jonathan; et al. (March 2018). "BANYAN. XI. The BANYAN Σ Multivariate Bayesian Algorithm to Identify Members of Young Associations with 150 pc". Astrophysical Journal. 856 (1): 23. arXiv:1801.09051. Bibcode:2018ApJ...856...23G. doi:10.3847/1538-4357/aaae09. ISSN 0004-637X. S2CID 119185386.
  13. 1 2 Kuffmeier, M.; Goicovic, F. G.; Dullemond, C. P. (2020), "Late encounter events as source of disks and spiral structures", Astronomy & Astrophysics, 633: A3, arXiv:1911.04833, doi:10.1051/0004-6361/201936820, S2CID 207863630
  14. ↑ "Astronomers Found Spirals Inside a Dust Gap of a Young Star Forming Disk". ALMA. Archived from the original on 2020-05-28. Retrieved 2020-02-22.
  15. 1 2 Oppenheimer, Ben R.; et al. (2008). "The Solar-System-Scale Disk around AB Aurigae". The Astrophysical Journal. 679 (2): 1574–1581. arXiv:0803.3629. Bibcode:2008ApJ...679.1574O. doi:10.1086/587778. S2CID 17424945.
  16. ↑ Jorquera, Sebastián; et al. (2022), "Large Binocular Telescope Search for Companions and Substructures in the (Pre)transitional Disk of AB Aurigae", The Astrophysical Journal, 926 (1): 71, arXiv:2201.08867, Bibcode:2022ApJ...926...71J, doi:10.3847/1538-4357/ac4be4, S2CID 246240894
  17. 1 2 3 4 Currie, Thayne; et al. (4 April 2022). "Images of embedded Jovian planet formation at a wide separation around AB Aurigae". Nature Astronomy. Springer Science and Business Media LLC. 6 (6): 751–759. arXiv:2204.00633. Bibcode:2022NatAs...6..751C. doi:10.1038/s41550-022-01634-x. ISSN 2397-3366. S2CID 247940163.
  18. ↑ Zhou, Yifan; Sanghi, Aniket; Bowler, Brendan P.; Wu, Ya-Lin; Close, Laird M.; Long, Feng; Ward-Duong, Kimberly; Zhu, Zhaohuan; Kraus, Adam L.; Follette, Katherine B.; Bae, Jaehan (2022), "HST/WFC3 Hα Direct-imaging Detection of a Pointlike Source in the Disk Cavity of AB Aur", The Astrophysical Journal Letters, 934 (1): L13, arXiv:2207.06525, Bibcode:2022ApJ...934L..13Z, doi:10.3847/2041-8213/ac7fef, S2CID 251064702
  19. ↑ Cody, Ann Marie; Tayar, Jamie; Hillenbrand, Lynne A.; Matthews, Jaymie M.; Kallinger, Thomas (March 2013). "Precise High-cadence Time Series Observations of Five Variable Young Stars in Auriga with MOST". The Astronomical Journal. 145 (3): 79. arXiv:1302.0018. Bibcode:2013AJ....145...79C. doi:10.1088/0004-6256/145/3/79. S2CID 1261183. Retrieved 29 October 2021.

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