About Mkn 177

ATel #4197; L. K. Erastova, Byurakan Observatory, Armenia
on 21 Jun 2012; 10:55 UT
Credential Certification: Lida Erastova (lke@bao.sci.am)

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About Mkn 177 L.K. Erastova (Byurakan Observatory, Armenia) Though Markarian galaxies are being very intensively studied all over the world, a number of these galaxies and even the majority of them still may present surprises. One of these galaxies is Mkn 177. This object was discovered by Markarian (1969, Astrofizika, 5, 443) and published in his second list of the UV-continuum galaxies. The slit spectrum was obtained by Arakelian et al. (1972, Astrofizika, 8, 33). In the Catalogue of SBS objects it is included as galaxy with peculiar morphology (Petrosian et al. 2007, ApJ Suppl, 170, 33) and the morphological type is 13, i.e. BCG. However, the investigation of its image and spectrum in the SDSS survey (The Sloan Digital Sky Survey, SDSS, http://www.sdss.org/dr7 ) shows that this object consists of compact diffuse and bright stellar-like objects, the latter being located within the diffuse region. Such cases, when a star or a quasar is projected on a galaxy are enough often. But the spectrum of the stellar-like component, which is given in these releases, shows very broad emission Balmer lines and it may be classified as a Sy1, and the spectrum of the diffuse part is SBN. Both components practically have the same redshifts. Therefore we can suggest that: it is only one galaxy, which consists of two circumnuclear regions, one of them is a Sy1 type AGN and the second is an SBN region. We will consider that it is only one object. According to the SDSS, the sizes of this galaxy are 0,49x0,39 arcmin. On the FBS and POSS1 images the galaxy is stellar-like and its size according to Markarian is ~12 arcsec. The examination of the SDSS image shows that on the background of the diffuse image a bright stellar-like, almost stellar objects is seen located at ~7 arcsec distance from the center of the image. It appeared that both diffuse and stellar-like components spectra have been obtained in the SDSS (z=0.0078 and z=0.0085). Published errors of these data show that the difference between the redshifts does not exceed the errors of the measurements. The stellar object has broad permitted asymmetric emission lines of Balmer series and is a Sy1 type galaxy with relatively narrow lines and the diffuse region has an SBN spectrum. The peculiarity of this object is the fact that it is fairly not so distant naked Sy1 type galaxy of small sizes located by its luminosity near the lower limit of absolute magnitudes typical of Seyfert type galaxies. The object has an oval form and blue colour on the DSS1and DSS2 images. Many galaxies of BCDG type just have such forms and sizes. It is well possible that detailed spectral investigations of its individual inclusions, similar cases may be found and the classification of these galaxies will need changes. Thus we come to a conclusion that Mkn 177 is an absolutely weak Sy1-type galaxy with M~-16, but completely not a BCDG or BCG located in our vicinities. Most probably we see only its nuclear region. Hence we can conclude that the lists of known BCDGs are not so reliable and possibly many such examples may be found among them. It should be noted that existence of broad lines or broad wings of Balmer lines in some BCDGs was reported in some papers (for example, Izotov et al. 2008 AJ, 687, 133). Though these examples are not so convincing, it should be verified where these lines arise, i.e. which parts of the galaxy produce them. To conclude, we think that Mkn 177 is not a BCDG, but a Sy1 type galaxy with relatively narrow lines for Sy1. In different publications either the galaxy UGCA 239 has been described (for example, Petrosian et al. 2001, Astrofizika, 44, 143) or an AGN (Zhou et al. 2006 ApJ., Suppl., 166, 128; Zamfir et al. 2008, MNRAS, 387, 856), although in earlier publications this object was described as most probably a double. Really this is the same galaxy Mkn 177.