Cellone, S.A. and Buzzoni, A.: "The low-luminosity galaxy population in the NGC5044 group"

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Cellone, S.A., and Buzzoni, A.:
"The low-luminosity galaxy population in the NGC 5044 group",
2005, MNRAS, 356, 41

Summary:

We present multicolour imaging for a sample of 33 dwarf and intermediate-luminosity galaxies in the field of the NGC 5044 Group, complemented with mid-resolution spectroscopy for a subsample of 13 objects. A revised membership and morphological classification is made for the galaxies in the sample. Our deep surface photometry provided clear evidences for disc structure in at least three galaxies previously catalogued as dE or dS0. Their transition-type properties are also evident from the c-m diagram, where they lie near the late-type galaxies locus, suggesting an evolutionary connection between a parent disc-galaxy population and at least part of present-day dEs. Half a dozen new dSph candidates were also found, most of them at small projected distances from NGC 5044, the central galaxy of the Group. The NGC 5044 Group appears clearly defined in redshift space, with a mean heliocentric radial velocity, V(rad) = 2461±84 km/s (z = 0.0082), and a moderate dispersion, σ(Vrad) = 431 km/s. Our kinematical data show no luminosity segregation for early-type galaxies: both dwarf and bright E/S0 systems show very similar velocity distributions [σ(Vrad) = 290 km/s], in contrast to late-type galaxies that seem to display a broader distribution [σ(Vrad) = 680 km/s].

To track back this project see also link 1 and link 2 locally, as well as

Sergio Cellone's Web pages @UNLP, Argentina

NGC 5044 (E) - The central galaxy of the group NGC 5054 (Sb) - The 2-nd ranked high-luminosity member

[click on the images to enlarge]

Pick up the paper at Astro-ph/04010463 Local link to the gzipped Postscript version (1.67Mb)

HTML version at the MNRAS site (*) PDF file at the MNRAS site (*)

(*) Requires password

Browse the figures in full gif/jpeg format (click on the thumbnails)

Observed photometric parameters for all the galaxies accounted for in this work can be found in this ASCII file.

Figure 1 - DSS image of the NGC 5044 Group, showing our observed fields. The frame is 90 arcmin on a side, North up, East to the left.

Figure 2 - True-colour atlas of all galaxies in the sample (composite images from the Gunn griz photometry). The faintest surface brightness threshold achieved in the pictures is about μ(g) ~ 26.5 mag/sq". Scale is the same for all frames, i.e. either 1 arcmin (small frames), 2 arcmin (mid-size frames), or 3 arcmin on a side (big frmaes). North is up, East to the left.

Figure 3 - Radial velocity distribution for galaxies within ~45 arcmin from NGC 5044. Filled bars correspond to new data presented in this paper, while empty ones show data from the literature. (a) All galaxies; (b) galaxies with v(rad) < 8000 km/s.

Figure 4 - Contour plots from g-band images fir the six new dSph candidates, plus the imaged field for galaxies N49A and N83A, already reported in Cellone (1999). The faintest contour corresponds to μ(g) = 26.5 mag/sq", with Δμ = 0.5 mag/sq" between adjacent contours. Each image is 1 arcmin on a side, with North up and East to the left. A coordinate list of the six new galaxies can be found in this ASCII file.

Figure 5 - Fraction of galaxy light beyond the isophotal radius vs. isophotal to effective radius ratio. Circles: E--dE; pentagons: S0--dS0; squares: Sa--Sc; triangles: Sd--Im. Filled symbols: definite members; open symbols: background objects; half-filled symbols: dubious cases. Symbol sizes are proportional to integrated magnitudes. Curves obtained from eq. (1) are shown for n=0.25, n=0.4, n=1, and n=2. Note the outlier object (N42 in our catalog) at F(ρ27)=-0.18, as discussed in the text.

Figure 6 - Mean effective surface brightness vs. integrated magnitude, both obtained from the model fits in the g Gunn band. Symbol coding is the same as for Fig. 5. Dashed line: constant effective radius, ρ_S(e) = 3 arcsec. Solid lines: survey limits in FS90 (equivalent to ρ=8 arcsec at μ(B) = 27 mag/sq"), for n=0.25, n=0.4, n=1, and n=2. Galaxies N42 and N54 (see text) are labelled. Photometry has been corrected for Galactic reddening according to Burstein and Heiles (1982).

Figure 7 - Isophotal colour -- magnitude diagram for our sample. Symbol coding is the same as for Fig.5, except that dotted open symbols correspond to background objects with known redshifts corrected to the distance of the NGC 5044 Group. The dashed line is the R vs. B-R, relation for Coma dEs from Secker et al. (1997), transformed to the Gunn system and corrected for distance. Data have been corrected for Galactic reddening according to Burstein and Heiles (1982), as explained in Sec. 5.2.

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AB/May 2005


NGC 5044 (E) - The central galaxy of the group	NGC 5054 (Sb) - The 2-nd ranked high-luminosity member
	[click on the images to enlarge]

	Pick up the paper at Astro-ph/04010463		Local link to the gzipped Postscript version (1.67Mb)

	HTML version at the MNRAS site (*)		PDF file at the MNRAS site (*)

	*() Requires password**

	Observed photometric parameters for all the galaxies accounted for in this work can be found in this ASCII file.
	Figure 1 - DSS image of the NGC 5044 Group, showing our observed fields. The frame is 90 arcmin on a side, North up, East to the left.
	Figure 2 - True-colour atlas of all galaxies in the sample (composite images from the Gunn griz photometry). The faintest surface brightness threshold achieved in the pictures is about μ(g) ~ 26.5 mag/sq". Scale is the same for all frames, i.e. either 1 arcmin (small frames), 2 arcmin (mid-size frames), or 3 arcmin on a side (big frmaes). North is up, East to the left.
	Figure 3 - Radial velocity distribution for galaxies within ~45 arcmin from NGC 5044. Filled bars correspond to new data presented in this paper, while empty ones show data from the literature. (a) All galaxies; (b) galaxies with v(rad) < 8000 km/s.
	Figure 4 - Contour plots from g-band images fir the six new dSph candidates, plus the imaged field for galaxies N49A and N83A, already reported in Cellone (1999). The faintest contour corresponds to μ(g) = 26.5 mag/sq", with Δμ = 0.5 mag/sq" between adjacent contours. Each image is 1 arcmin on a side, with North up and East to the left. A coordinate list of the six new galaxies can be found in this ASCII file.
	Figure 5 - Fraction of galaxy light beyond the isophotal radius vs. isophotal to effective radius ratio. Circles: E--dE; pentagons: S0--dS0; squares: Sa--Sc; triangles: Sd--Im. Filled symbols: definite members; open symbols: background objects; half-filled symbols: dubious cases. Symbol sizes are proportional to integrated magnitudes. Curves obtained from eq. (1) are shown for n=0.25, n=0.4, n=1, and n=2. Note the outlier object (N42 in our catalog) at F(ρ27)=-0.18, as discussed in the text.
	Figure 6 - Mean effective surface brightness vs. integrated magnitude, both obtained from the model fits in the g Gunn band. Symbol coding is the same as for Fig. 5. Dashed line: constant effective radius, ρ_S(e) = 3 arcsec. Solid lines: survey limits in FS90 (equivalent to ρ=8 arcsec at μ(B) = 27 mag/sq"), for n=0.25, n=0.4, n=1, and n=2. Galaxies N42 and N54 (see text) are labelled. Photometry has been corrected for Galactic reddening according to Burstein and Heiles (1982).
	Figure 7 - Isophotal colour -- magnitude diagram for our sample. Symbol coding is the same as for Fig.5, except that dotted open symbols correspond to background objects with known redshifts corrected to the distance of the NGC 5044 Group. The dashed line is the R vs. B-R, relation for Coma dEs from Secker et al. (1997), transformed to the Gunn system and corrected for distance. Data have been corrected for Galactic reddening according to Burstein and Heiles (1982), as explained in Sec. 5.2.