On the galaxy surrounding the BL Lacertae object MS 0205.7+3509



: Falomo R, Kotilainen J, Pursimo T, Sillanpaa A, Takalo L, Heidt J

Publisher: EDP SCIENCES S A

: 1997

: ASTRONOMY & ASTROPHYSICS

: ASTRON ASTROPHYS

: 321

: 2

: 374

: 378

: 5

: 0004-6361


We present high spatial resolution optical images of the BL Lac object MS 0205.7+3509 in the R filter, that allow us to discuss and clarify its anomalous properties. The source was previously claimed to be surrounded by a nebulosity decentered with respect to the bright nucleus. In addition the host was claimed to be a disc dominated galaxy, contrary to the large majority of the hosts of BL Lacs. We find that there is a companion galaxy at about 2 '' from MS 0205.7+3509, which is responsible for many of the anomalous properties reported for this source. The observations are discussed in the context of the microlensing hypothesis for BL Lacs.



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