scholarly journals UGC 1378 – a Milky Way sized galaxy embedded in a giant low surface brightness disc

2019 ◽  
Vol 489 (4) ◽  
pp. 4669-4678 ◽  
Author(s):  
Anna S Saburova ◽  
Igor V Chilingarian ◽  
Anastasia V Kasparova ◽  
Ivan Yu Katkov ◽  
Daniel G Fabricant ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Milky Way ◽  
High Surface ◽  
Wide Field ◽  
High Surface Brightness ◽  
Dispersion Data ◽  
Low Surface Brightness ◽  
Stellar Velocity ◽  
Major Merger ◽  
Gas Accretion

ABSTRACT The dominant physical processes responsible for the formation and longevity of giant gaseous and stellar discs in galaxies remain controversial. Although they are rare (less than 10 confirmed as of now), giant low-surface brightness (gLSB) discy galaxies provide interesting insights given their extreme nature. We describe observations of UGC 1378 including deep spectroscopy with the Russian 6-m telescope and multiband imaging with Binospec at the MMT. Galaxy UGC 1378 has both high surface brightness and an extended low surface brightness discs. Our stellar velocity dispersion data for the high surface brightness, Milky Way sized, disc appears inconsistent with a recent major merger, a widely discussed formation scenario for the very extended low surface brightness disc. We estimate the star formation rates (SFRs) from archival Wide-Field Infrared Survey Explorer data. The SFR surface density in the LSB disc is low relative to its gas density, consistent with recent gas accretion. We argue that the unusually large size of UGC 1378’s disc may be the product of a rich gas reservoir (e.g. a cosmic filament) and an isolated environment that has preserved the giant disc.

High dispersion spectra of Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 242-242
Author(s):  
S. Hyung ◽  
L. H. Aller
Keyword(s):  
Plasma Diagnostics ◽  
Surface Brightness ◽  
High Surface ◽  
Planetary Nebulae ◽  
High Dispersion ◽  
Chemical Compositions ◽  
Echelle Spectrograph ◽  
High Surface Brightness ◽  
Low Surface Brightness ◽  
Ngc 7662

Determinations of the plasma diagnostics and chemical compositions of planetary nebulae require ultimately high dispersion spectra. For objects of high surface brightness the Hamilton Echelle Spectrograph at Lick Observatory is satisfactory for the region 3650–10100Å which involves the 168th to 56th echelle orders. For a slit width of 640 μm amounting to 1.15 arcsec at the Coude focus, the actual spectral resolution (FWHM) is about 0.2Å at 8850Å. The length of the slit is chosen as 4.0 arcsec. Hyung (1994) & Aller (1994) describe the observing procedure. Since the Hamilton echelle was designed primarily for star-like sources, it is not useful for extended low surface brightness PN. The earlier observations were obtained with an 800 × 800 chip that did not cover the echelle field, so several settings were needed. Later, we used a slower 2048 × 2048 chip which covered the whole field and was somewhat more efficient at longer wavelengths. The program has been completed and definitive measurements have obtained for NGC 2440, NGC 6543, NGC 6741, NGC 6818, NGC 7026, NGC 7662, and Hu 1-2. All of these PN display particularly rich, interesting spectra. Previously observed and published objects include IC 351, IC 418, IC 2149, IC 4997, NGC 6567, NGC 6572, NGC 6790, NGC 6886, NGC 7009, BD +30 3639, & Hubble 12. NGC 6884 is in press. Additional nebulae which are yet to be discussed are IC 4634, IC 4846, IC 5117, NGC 6210, & NGC 6803.

scholarly journals The σc — Vcirc correlation in high and low surface brightness galaxies

2004 ◽  
Vol 220 ◽  
pp. 339-340 ◽  
Author(s):  
A. Pizzella ◽  
E. Dalla Bontà ◽  
E. M. Corsini ◽  
L. Coccato ◽  
F. Bertola
Keyword(s):  
Surface Brightness ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
High Surface ◽  
Linear Scale ◽  
High Surface Brightness ◽  
Circular Velocity ◽  
Straight Line ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies

We investigate the relation between the central velocity dispersion, σc, and the circular velocity, Vcirc, in galaxies. in addition to previously obtained data, we consider an observationally homogeneus sample of 52 high surface brightness and 11 low surface brightness spiral galaxies. We performed a straight line regression analysis in a linear scale, finding a good fit, also for low σc galaxies, always rejected in the previous studies. Low surface brightness galaxies seem to behave differently, showing either higher values of Vcirc or lower values of σc with respect to their high surface brightness counterparts.

scholarly journals Stellar Populations of Dwarf Galaxies

1995 ◽  
Vol 164 ◽  
pp. 430-431
Author(s):  
Elchanan Almoznino ◽  
Noah Brosch
Keyword(s):  
Surface Brightness ◽  
Dwarf Galaxies ◽  
High Surface ◽  
Stellar Populations ◽  
Virgo Cluster ◽  
Original Sample ◽  
High Surface Brightness ◽  
Brightness Level ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies

We selected a sample of dwarf galaxies in the Virgo cluster from the original catalog of Bingelli, Sandage and Tamman (1985), which have been measured at 21 cm by Hoffman et al. (1987). The original sample was selected to have both high surface brightness objects (classified as BCD or anything/BCD), and low surface brightness galaxies (classified as ImIII, ImIV or ImV). An additional selection was done on the total amount of HI, as given in Hoffman et al. We selected from each surface brightness group objects with high HI content (flux integral larger than a set threshold), and others with low HI content. We thus defined four samples differing in surface brightness level and total HI content.

scholarly journals Morphology and Stellar Populations in the Gas-Rich, Giant LSBGs

1999 ◽  
Vol 171 ◽  
pp. 191-195 ◽  
Author(s):  
P. Knezek
Keyword(s):  
Entire Range ◽  
Surface Brightness ◽  
Spiral Galaxies ◽  
High Surface ◽  
Nuclear Spectroscopy ◽  
Nuclear Activity ◽  
High Surface Brightness ◽  
Low Surface Brightness ◽  
Show Evidence ◽  
Low Surface Brightness Galaxies

AbstractAn unexpected characteristic of low surface brightness galaxies (LSBGs) is that a significant number are massive and possess substantial amounts of atomic gas. We present preliminary results of an ongoing program to obtain BVRIJHK imaging, along with some nuclear spectroscopy, of a well-defined sample of LSBGs which are gas-rich and of similar size to giant, high surface brightness spiral galaxies (HSBGs). These LSBGs span the entire range of Hubble disk morphologies. While their disks are bluer, on average, than comparable HSBGs, the optical morphology of massive LSBGs indicates that many of these systems have undergone previous star formation episodes. They typically have long disk scale lengths, and range from MB = −16 to −22 (H0 = 75 km s−1 Mpc−1). About half of the LSBGs with bulges show evidence of nuclear activity, and ~30% appear to be barred. These massive, gas-rich LSBGs apparently have varied, and often complex, evolutionary histories.

scholarly journals The origin of low-surface-brightness galaxies in the dwarf regime

2021 ◽  
Vol 502 (3) ◽  
pp. 4262-4276
Author(s):  
R A Jackson ◽  
G Martin ◽  
S Kaviraj ◽  
M Ramsøy ◽  
J E G Devriendt ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
High Surface ◽  
Stellar Mass ◽  
Current Data ◽  
Sloan Digital Sky Survey ◽  
Data Sets ◽  
Low Surface Brightness ◽  
Gas Accretion ◽  
Low Surface Brightness Galaxies

ABSTRACT Low-surface-brightness galaxies (LSBGs) – defined as systems that are fainter than the surface-brightness limits of past wide-area surveys – form the overwhelming majority of galaxies in the dwarf regime (M⋆ < 109 M⊙). Using NewHorizon, a high-resolution cosmological simulation, we study the origin of LSBGs and explain why LSBGs at similar stellar mass show the large observed spread in surface brightness. NewHorizon galaxies populate a well-defined locus in the surface brightness–stellar mass plane, with a spread of ∼3 mag arcsec−2, in agreement with deep Sloan Digital Sky Survey (SDSS) Stripe 82 data. Galaxies with fainter surface brightnesses today are born in regions of higher dark matter density. This results in faster gas accretion and more intense star formation at early epochs. The stronger resultant supernova feedback flattens gas profiles at a faster rate, which, in turn, creates shallower stellar profiles (i.e. more diffuse systems) more rapidly. As star formation declines towards late epochs ( z < 1), the larger tidal perturbations and ram pressure experienced by these systems (due to their denser local environments) accelerate the divergence in surface brightness, by increasing their effective radii and reducing star formation, respectively. A small minority of dwarfs depart from the main locus towards high surface brightnesses, making them detectable in past wide surveys (e.g. standard-depth SDSS images). These systems have anomalously high star formation rates, triggered by recent fly-by or merger-driven starbursts. We note that objects considered extreme or anomalous at the depth of current data sets, e.g. ‘ultra-diffuse galaxies’, actually dominate the predicted dwarf population and will be routinely visible in future surveys like the Legacy Survey of Space and Time (LSST).

scholarly journals Gasdynamics and Starbursts in Interacting Galaxies

1999 ◽  
Vol 186 ◽  
pp. 205-212 ◽  
Author(s):  
J. Christopher Mihos
Keyword(s):  
Surface Brightness ◽  
High Surface ◽  
Disk Surface ◽  
Interacting Galaxies ◽  
Host Galaxies ◽  
Direct Function ◽  
High Surface Brightness ◽  
Low Surface Brightness ◽  
The Stability ◽  
Low Surface Brightness Galaxies

The onset of gaseous inflows and central activity in interacting galaxies is driven largely by induced bars in the host galaxies. The stability of galaxies against growing bar modes is a direct function of their structural properties — galaxies with central bulges or low disk surface densities are more stable against central starbursts than are bulgeless or disk-dominated systems. Low surface brightness galaxies prove less prone to bar formation and central starbursts than do normal high surface brightness galaxies. This stability of LSB disks also resolves many of the dynamical pitfalls encountered when attempting to link poststarburst “E+A” galaxies to interactions involving normal high surface brightness galaxy progenitors.

scholarly journals Edge-on Low Surface Brightness Galaxies in the SDSS and the Red Halo Phenomenon

2006 ◽  
Vol 2 (S235) ◽  
pp. 82-82
Author(s):  
Brady Caldwell ◽  
Nils Bergvall
Keyword(s):  
Surface Brightness ◽  
Stellar Population ◽  
High Surface ◽  
Disk Galaxies ◽  
High Surface Brightness ◽  
Polar Direction ◽  
Low Surface Brightness ◽  
Compact Galaxies ◽  
Low Surface Brightness Galaxies ◽  
Lsb Galaxies

AbstractExtremely red halos have been detected around high surface brightness (HSB) disk galaxies and blue compact galaxies. We analyse the halo emission of a sample of 970 stacked edge-on low surface brightness (LSB) galaxies in the SDSS (DR4) down to μg ~ 30 mag arcsec−2. These are divided by g − r colour limits into a “blue” Sample A (336 galaxies), “yellow” Sample B (318 galaxies) and “red” Sample C (316 galaxies). The gri colours indicate a prominent red excess in the polar direction, strongly deviating from any normal stellar population.

scholarly journals Stellar populations of bulges in galaxies with a low surface-brightness disc

2012 ◽  
Vol 10 (H16) ◽  
pp. 340-340
Author(s):  
L. Morelli ◽  
E. M. Corsini ◽  
A. Pizzella ◽  
E. Dalla Bontà ◽  
L. Coccato ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Stellar Population ◽  
High Surface ◽  
Line Strength ◽  
Stellar Populations ◽  
Element Abundance ◽  
High Surface Brightness ◽  
Central Value ◽  
Radial Profiles ◽  
Low Surface Brightness

AbstractThe radial profiles of the Hβ, Mg, and Fe line-strength indices are presented for a sample of eight spiral galaxies with a low surface-brightness stellar disc and a bulge. The correlations between the central values of the line-strength indices and velocity dispersion are consistent to those known for early-type galaxies and bulges of high surface-brightness galaxies. The age, metallicity, and α/Fe enhancement of the stellar populations in the bulge-dominated region are obtained using stellar population models with variable element abundance ratios. Almost all the sample bulges are characterized by a young stellar population, on-going star formation, and a solar α/Fe enhancement. Their metallicity spans from high to sub-solar values. No significant gradient in age and α/Fe enhancement is measured, whereas only in a few cases a negative metallicity gradient is found. These properties suggest that a pure dissipative collapse is not able to explain formation of all the sample bulges and that other phenomena, like mergers or acquisition events, need to be invoked. Such a picture is also supported by the lack of a correlation between the central value and gradient of the metallicity in bulges with very low metallicity. The stellar populations of the bulges hosted by low surface-brightness discs share many properties with those of high surface-brightness galaxies. Therefore, they are likely to have common formation scenarios and evolution histories. A strong interplay between bulges and discs is ruled out by the fact that in spite of being hosted by discs with extremely different properties, the bulges of low and high surface-brightness discs are remarkably similar.

scholarly journals X-ray Interferometry

2001 ◽  
Vol 205 ◽  
pp. 457-462
Author(s):  
Webster Cash
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Surface Brightness ◽  
High Surface ◽  
X Rays ◽  
High Surface Brightness ◽  
X Ray

X-rays have tremendous potential for imaging at the highest angular resulution. The high surface brightness of many x-ray sources will reveal angular scales heretofore thought unreachable. The short wavelengths make instrumentation compact and baselines short. We discuss how practical x-ray interferometers can be built for astronomy using existing technology. We describe the Maxim Pathfinder and Maxim missions which will achieve 100 and 0.1 micro-arcsecond imaging respectively. The science to be tackled with resolution of up to one million times that of HST will be outlined, with emphasis on eventually imaging the event horizon of a black hole.

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