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.
Mary Doris Applegate Beach discovered that AB Aurigae is a variable star by examining 150 photographic plates taken between 1914 and 1921. Her discovery was announced in 1921.[12]
The protoplanetary disk of AB Aurigae as seen by the ERIS instrument of the VLT in polarised light. The right side is zoomed-in version of the area showing the inner region of the disc, including the very-bright-yellow ‘twist’ where a planet is believed to be forming.
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] Evidence for unstable disk regions transforming into companions, possibly supporting such a formation of AB Aurigae b was reported in a Nature paper published in September 2024.[18] The planet was independently detected in July 2022.[19]
↑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.
12Nicolet, 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.
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