Contents

AB Aurigae

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]

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 M_J, 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]

• 
  AB Aurigae and its dust disk seen by Hubble
• 
  A light curve for AB Aurigae from MOST satellite data, adapted from Cody et al. (2013)^[19]
• 
  Hubble Space Telescope images of protoplanet AB Aurigae b.

• Telleschi, A.; et al. (2007). "The first high-resolution X-ray spectrum of a Herbig star: AB Aurigae". Astronomy and Astrophysics. 468 (2): 541–556. arXiv:astro-ph/0610456. Bibcode:2007A&A...468..541T. doi:10.1051/0004-6361:20065422. S2CID 14242067.
• Bitner, Martin A.; et al. (2007). "TEXES Observations of Pure Rotational H₂ Emission from AB Aurigae". The Astrophysical Journal. 661 (1): L69–L72. arXiv:0704.1481. Bibcode:2007ApJ...661L..69B. doi:10.1086/518717. S2CID 14473137.
• Fukagawa, Misato; et al. (2004). "Spiral Structure in the Circumstellar Disk around AB Aurigae". The Astrophysical Journal. 605 (1): L53–L56. Bibcode:2004ApJ...605L..53F. doi:10.1086/420699. S2CID 123196140.
• Keller, L. P.; et al. (2002). "Identification of iron sulphide grains in protoplanetary disks". Nature. 417 (6885): 148–150. Bibcode:2002Natur.417..148K. doi:10.1038/417148a. PMID 12000914. S2CID 4420339.

• Overbye, Dennis (26 March 2008). "Star's Dust May Hold Clue to New Planet". New York Times. Retrieved 2021-03-06.
• Image AB Aurigae
• "Image AB Aurigae". SIMBAD. Retrieved 2008-08-20.
• "AB Aurigae". jumk.de. Retrieved 2008-10-15.
• "Spiral Dance in a Planetary Nursery". Subaru Telescope. Retrieved 2008-10-15.
• "The Source of Stellar Magnetism". news.softpedia.com. 26 February 2007. Retrieved 2008-10-16.
• "XMM-Newton unlocks magnetic mystery". iTWire. Retrieved 2008-10-16.
• "Silicate Stardust in Meteorites". Planetary science research. Retrieved 2008-10-16.
• "Image Multimedia Gallery ESA". ESA. Retrieved 2008-10-16.
• "ESO Telescope Sees Signs of Planet Birth". European Southern Observatory. Retrieved 2021-03-06.

Archived:

• Overbye, Dennis (2008-03-26). "Star's Dust May Hold Clue to New Planet". www.nytimes.com. Archived from the original on December 10, 2008. Retrieved 2008-08-20.
• "AB Aurigae: How To Make Planets". NASA. Archived from the original on 29 September 2008. Retrieved 2008-08-20.
• "Planet in Progress? Evidence Of A Huge Planet Forming In Star System". Science News. Archived from the original on 10 October 2008. Retrieved 2008-10-15.