J/A+A/279/61 J/A+A/279/61 extinction and star clusters in NGC 1275 H U Norgaard-Nielsen P Goudfrooij H E Jorgensen L Hansen Astron. Astrophys. 279 61 1993 1993A&A...279...61N galaxies: cooling flows galaxies: individual (NGC 1275) galaxies: interactions galaxies: ISM galaxies: star clusters Our CCD images reveal that some of the well-known absorption features in NGC 1275 do not show up in the distribution of the low velocity (LV) ionized gas. The absorption features have the same asymmetrical distribution around the nucleus as the high velocity (HV) emission line system. The extinction of the features is significantly different from the Galactic law. Our analysis shows that the dust responsible for the extinction is most probably well within NGC 1275. Altogether, we argue that most of the absorption features are associated with the HV system, implying that the HV system has moved halfway through NGC 1275. We have found many more objects than recently discovered by Hubble Space Telescope (HST)(Holtzman et al. 1992). We have been able to define three groups of objects with distinct differences in distribution around the nucleus: (1) a group of mainly giant H II regions, nearly all associated with the HV system, (2) old globular clusters in a total number of about 2/3 of the number of globular clusters in M87 (assuming a universal luminosity function of globular clusters), and (3) an intermediate group (IG), of both extended and point sources, with 0.0 less than or equal to (V-I)(sub 0) less than or equal to 0.75. The IG is peaking strongly at the nucleus of NGC 1275, with a smooth and symmetrical distribution. For the extended IG objects, we estimate an age less than or equal to 10(exp 7) yr, while the point sources could have ages 10(exp 7) to 10(exp 9) yr. We suggest that the IG objects have been formed in a cooling catastrophe, set up in the central part of the extended X-ray emitting gas of the Perseus Cluster. Very little (except for the giant H II regions) excess light in our V frame can be associated with the HV system. We find -16.1 greater than or equal to M(sub V)(HV) greater than or equal to -17.3, implying that the HV system is extremely luminous in hydrogen alpha compared to the visual luminosity.

Object When starting with H, object observed by Holtzman et al. (1992) When starting with N, new object --- D_RA offset in right ascension from the nucleus arcsec D_DE offset in declination from the nucleus. The coordinate system of Holtzman et al. is rotated 2 deg NE arcsec V0 magnitude, corrected for Galactic extinction Av = 0.54 mag e_V0 photon noise in the V magnitude mag (V-I)0 color corrected for Galactic extinction E(V-I) = 0.28 mag e_(V-I)0 photon noise in (V-I)0 mag V0,H magnitude by Holztamn et al. corrected for Galactic extinction Av mag e_V0,H photon noise in the V0 magnitude mag (V-R)0 color by Holtzman et al. corrected for Galactic extinction E(V-R) = 0.14 mag e_(V-R)0 photon noise in (V-R)0 mag LV When +, the object is associated with a LV Halpha emission knot --- HV When +, the object is associated with a LV Halpha emission knot when ?, the object could be associated with HV Halpha emission knot --- group 1: old globular clusters 2: intermediate group objects 3: giant H II regions 4: foreground stars --- Comments Holtzman et al. objects included in our diaphragm. extended: object classified as diffuse by Holtzman et al. --- Patricia Bauer CDS 1993Oct27 J_A+A_279_61.xml