scholarly journals B and R Surface Photometry of Faint Galaxies in the Area of Three Cosmic Voids

1996 ◽  
Vol 171 ◽  
pp. 461-461
Author(s):  
J. Vennik ◽  
B. Kovachev ◽  
U. Hopp ◽  
B. Kuhn
Keyword(s):  
Power Law ◽  
Ellipse Fitting ◽  
Surface Photometry ◽  
Late Type ◽  
Nearby Galaxies ◽  
Cosmic Voids ◽  
Light Profiles ◽  
Calar Alto

We performed B and R surface photometry of 92 faint mostly late type galaxies, selected towards three nearby voids (Hopp et al., 1995 A&AS 109, 537). CCD frames were taken with the Calar Alto 3.5m telescope and with the MPIA/ESO 2.2m telescope. We calculated the azimuthally averaged equivalent profiles, asymtotic total magnitudes and colours, and performed ellipse-fitting of isophotes. Observed light profiles were fitted with a power law μ = μ0 + 1.086αr1/n. About 40% of profiles are pure exponentials (n = 1); 38% of the profiles reveal a bulge/disk or disk/disk composition; 20% of them show central light depression. We classified the nearby galaxies (z ≤ 0.04) as being related either to clusters (11 galaxies), to sheets (23) or to voids (9). The obtained parameters are compared to those of HSB and of LSB field galaxies.

scholarly journals Global Properties of Nearby Galaxies

1994 ◽  
Vol 161 ◽  
pp. 559-566
Author(s):  
M. Capaccioli ◽  
N. Caon ◽  
M. D'onofrio
Keyword(s):  
Growth Curves ◽  
Large Field ◽  
Medium Size ◽  
Wide Field ◽  
Surface Photometry ◽  
Indirect Methods ◽  
Research Areas ◽  
The Galaxy ◽  
Nearby Galaxies ◽  
Light Profiles

Surface photometry of nearby galaxies is among the research areas that gained most from the recent advances in ‘wide-field imaging’. In fact, the demand for an accurate measure of the night-sky level all around the target galaxy — a key step in galaxy surface photometry; see Fig. 1 in Capaccioli & de Vaucouleurs (1983) — calls for at least some images covering a field wider than the size of the object under study. So far, the small field of most CCD cameras attached to the Cassegrain foci of medium-size telescopes has prevented both the mapping of the galaxian outskirts and, a fortiori, a direct measurement of the sky background μs on the galaxy image itself. Indirect methods to estimate μs — blank-sky exposures, matching of growth curves to photoelectric integrated magnitudes, assumptions on the shape of the galaxian light profiles — have proven ineffective and/or methodologically questionable (Capaccioli 1989). Until large-format CCD chips or mosaics are routinely used, the only way out of these problems is either the use of focal reducers, whose optical complexity may however be incompatible with photometric accuracy, or of large-field photographic plates.

B and R Surface Photometry of Faint Galaxies in the Area of Three Cosmic Voids

1996 ◽  
pp. 461-461
Author(s):  
J. Vennik ◽  
B. Kovachev ◽  
U. Hopp ◽  
B. Kuhn
Keyword(s):  
Surface Photometry ◽  
Cosmic Voids

Spatially resolved dust-to-gas mass ratios in nearby galaxies

2019 ◽  
Vol 15 (S341) ◽  
pp. 78-82
Author(s):  
Basilio Solís-Castillo ◽  
Marcus Albrecht
Keyword(s):  
Power Law ◽  
Interstellar Dust ◽  
Conversion Factor ◽  
Strong Impact ◽  
Mass Ratio ◽  
Spatially Resolved ◽  
Nearby Galaxies ◽  
Hierarchical Bayesian Method ◽  
Factor Α ◽  
Infrared Data

AbstractWe analyse the dust-to-gas mass ratio (DGR) in nearby galaxies on kiloparsec scales. We focus on their dependence on metallicity and the CO-to-H2 conversion factor, αco. We use a sample of 25 nearby galaxies from SINGS and combine our data with CO (2-1) and H I observations from the HERACLES and THINGS surveys. We implement a Hierarchical Bayesian method to derive the dust mass via fitting the infrared data from 100 to 500 μm with a single modified blackbody. We find that the DGR-metallicity relation follows a power law and we study its strong dependency on the conversion factor αco. Our results indicate a strong connection between interstellar dust and gas. The resolved DGR-metallicity relation cannot be represented with a single power law. The scatter in this relation shows the strong impact of several processes that take place in every galaxy.

scholarly journals The growth of mass and metallicity in bulges and disks: CALIFA perspective

2012 ◽  
Vol 10 (H16) ◽  
pp. 338-338
Author(s):  
R. M. González Delgado ◽  
E. Pérez ◽  
R. Cid Fernandes ◽  
R. García-Benito ◽  
A. de Amorim ◽  
...  
Keyword(s):  
Spectral Synthesis ◽  
Morphological Type ◽  
Star Formation History ◽  
Stellar Ages ◽  
Formation History ◽  
History Of ◽  
Nearby Galaxies ◽  
First Time ◽  
Inside Out ◽  
Calar Alto

AbstractCALIFA (Calar Alto Legacy Integral Field Area) is a 3D spectroscopic survey of 600 nearby galaxies that we are obtaining with [email protected] at Calar Alto (Sánchez et al. 2012; Husemann et al. 2012). This pioneer survey is providing valuable clues on how the mass and metallicity grow in the different galactic spatial sub-components (“bulge” and “disk”). Processed through spectral synthesis techniques, CALIFA datacubes allow us to, for the first time, spatially resolve the star formation history of galaxies (Cid Fernandes et al. 2012). The richness of this approach is already evident from the results obtained for the first ~ 100 galaxies of the sample (Pérez et al. 2012). We have found that galaxies grow inside-out, and that the growth rate depends on a galaxy's mass. Here, we present the radial variations of physical properties sorting galaxies by their morphological type (Figure 1). We have found a good correlation between the stellar mass surface density, stellar ages and metallicities and the Hubble type, but being the the early type spirals (Sa-Sbc) the galaxies with strong negative age and metallicity gradient from the bulge to the disk.

scholarly journals Direct imaging of haloes and truncations in face-on nearby galaxies

2015 ◽  
Vol 11 (S317) ◽  
pp. 39-44
Author(s):  
J. H. Knapen ◽  
S. P. C. Peters ◽  
P. C. van der Kruit ◽  
I. Trujillo ◽  
J. Fliri ◽  
...  
Keyword(s):  
Point Spread Function ◽  
Spiral Galaxies ◽  
Surface Photometry ◽  
Direct Imaging ◽  
Point Spread ◽  
Deep Imaging ◽  
Spread Function ◽  
Stellar Halo ◽  
Nearby Galaxies ◽  
Proper Analysis

AbstractWe use ultra-deep imaging from the IAC Stripe 82 Legacy Project to study the surface photometry of 22 nearby, face-on to moderately inclined spiral galaxies. The reprocessed and co-added SDSS/Stripe 82 imaging allows us to probe down to 29–30 r′-mag/arcsec2 and thus reach into the very faint outskirts of the galaxies. We find extended stellar haloes in over half of our sample galaxies, and truncations in three of them. The presence of stellar haloes and truncations is mutually exclusive, and we argue that the presence of a stellar halo can hide a truncation. We find that the onset of the halo and the truncation scales tightly with galaxy size. We highlight the importance of a proper analysis of the extended wings of the point spread function (PSF), finding that around half the light at the faintest levels is from the inner regions of a galaxy, though not the nucleus, re-distributed to the outskirts by the PSF. We discuss implications of this effect for future deep imaging surveys, such as with the LSST.

scholarly journals A BVRIJKHα Survey of 355 Nearby Galaxies

1996 ◽  
Vol 171 ◽  
pp. 449-449
Author(s):  
Peter Surma
Keyword(s):  
Selection Criterion ◽  
Optical Observations ◽  
La Palma ◽  
The Galaxy ◽  
Theoretical Evolution ◽  
Bona Fide ◽  
Nearby Galaxies ◽  
Galaxy Population ◽  
The Moment ◽  
Calar Alto

A multiband CCD-survey of 355 UGC galaxies in our local cosmological neighbourhood is undertaken in collaboration with S.D.M. White (MPI-fAstrophysik Garching), S. McGaugh (IoA, Cambridge), M. Dennefeld (IAP Paris), H. Ferguson (STScI), M. Rieke, A. Grauer (Steward Obs. Arizona). Optical observations are obtained on Calar Alto (MPIA Heidelberg) and at La Palma (RGO) – with data 40% complete at the moment. The selection criterion is diameter 1.5′ < D25 < 2.5′. A database of local galaxy properties is being established (including total luminosities, mean SB, diameters, colours, colour gradients, D/B-ratios, present SFRs). Using theoretical evolution models we can predict the bona fide appearance of the galaxy population at any given redshift and thus provide a secure reference point to interpreting galaxies observed at intermediate and high z (e.g. faint galaxy counts).

scholarly journals Nuclear Activity in the Hickson Compact Groups of Galaxies

1999 ◽  
Vol 186 ◽  
pp. 418-418
Author(s):  
M. Shimada ◽  
S. Nishiura ◽  
Y. Ohyama ◽  
T. Murayama ◽  
Y. Taniguchi
Keyword(s):  
Emission Line ◽  
The Other ◽  
Compact Groups ◽  
Early Type ◽  
Late Type ◽  
No Emission ◽  
Nuclear Activity ◽  
Groups Of Galaxies ◽  
Nearby Galaxies ◽  
Hickson Compact Groups

In order to study environmental effects on the nuclear activity in galaxies, we have been conducting a spectroscopic study of Hickson Compact Groups of galaxies (HCGs, Hickson 1982) which are the densest agglomeration of galaxies. We obtained nuclear spectra of 62 galaxies in 29 HCGs in the spectral range 6200–7000Å with the 188cm telescope at Okayama Astrophysical Observatory. These spectra were classified into the three types by using the emission line ratio [NII]λ6583/Hα; (1) AGN: [NII]λ6583/Hα >0.6, (2) HII nuclei: [NII]λ6583/Hα <0.6, and (3) Absorption: no emission line. We compared the nuclear activity of galaxies in HCGs with that of nearby galaxies (Ho 1996; Ho, Filippenko & Sargent 1997) which provides a representative sample of field galaxies. In early-type spirals (Sa-Sbc), the fraction of HII nuclei in HCGs is smaller than that in the field galaxies, while the fraction of absorption in HCGs is larger than that in field galaxies. On the other hand, in early-type galaxies (E-S0a) and late-type spirals (Sc-P), we found little difference in the nuclear activity between HCGs and field galaxies.

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