Open AccessEvidence of asymmetric structure in the atmosphere of Mira variable U Orionis from lunar occultation observations in the near‐infrared
Author(s) -
Mondal Soumen,
Chandrasekhar T.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.07454.x
Subject(s) - physics , occultation , asymmetry , astrophysics , infrared , brightness , angular diameter , position angle , astronomy , atmosphere (unit) , stars , meteorology , galaxy , quantum mechanics
We present the infrared angular diameter of Mira variable U Ori, obtained from lunar occultation observations at 2.2 μm. The uniform disc (UD) angular diameter is determined to be 11.9 ± 0.3 mas at variability phase 0.28. The source brightness profile derived from a model‐independent analysis shows an asymmetric spatial structure. The dispersion in UD angular diameter measurements in comparison with other similar measurements at the same phase in the near‐infrared can be explained by a spatial asymmetry of the source, being elongated in the direction northeast – southwest, at position angle of 50°–70°. Several corollary evidences for the spatial asymmetry of the source are presented.