The neutral hydrogen content of early type disk galaxies

1991 ◽  
Vol 102 ◽  
pp. 572 ◽  
Author(s):  
J. Eder ◽  
R. Giovanelli ◽  
M. P. Haynes
Keyword(s):  
Hydrogen Content ◽  
Neutral Hydrogen ◽  
Disk Galaxies ◽  
Early Type

scholarly journals Outer rings of early-type disk galaxies

2015 ◽  
Vol 70 (3) ◽  
pp. 280-291 ◽  
Author(s):  
I. P. Kostiuk ◽  
O. K. Sil’chenko
Keyword(s):  
Disk Galaxies ◽  
Early Type

scholarly journals Lyman α Emission from Disk Absorption Systems in QSOs: Star Formation in Young Galaxy Disks

1989 ◽  
Vol 134 ◽  
pp. 557-559
Author(s):  
Harding E. Smith ◽  
Ross D. Cohen ◽  
Joseph E. Burns ◽  
David J. Moore ◽  
Barbara Uchida
Keyword(s):  
Rest Frame ◽  
High Redshift ◽  
Neutral Hydrogen ◽  
Disk Galaxies ◽  
List Type ◽  
Ionization State ◽  
Low Velocity ◽  
High Ionization ◽  
Dispersion Component ◽  
Disk Component

The strong self-damped Lyman α absorption systems present in the spectra of high redshift QSOs represent a unique population of absorber which has recently been associated with the precursors of current disk galaxies. In a low resolution survey for what we have come to call “Lyman α disk systems” performed at Lick Observatory (Wolfe, et al. 1986, Ap. J. Suppl. 61, 249) approximately 18 systems with confirmed damped Lyman α profiles and rest frame equivalent widths greater than 5 Å were detected in a sample of 68 high redshift QSOs (Smith, Cohen and Bradley 1986, Ap. J. 310, 583). Subsequent higher resolution study has shown these systems to have the following properties (Turnshek, et al. 1988, Ap. J., in press): 1.Neutral hydrogen column densities, 2 × 1020 ≤ NHI ≤ 8 × 1021 cm−2.2.Low-mixed ionization state. Typically the low ionization states dominate the high ionization states (e.g. CII ≫ CIV). Some enrichment has occurred, −2≲[X/H]⊙ ≲0.3.Gas density, n ≲ 1 cm−3.4.The gas shows two components, a quiescent (disk) component, σν ≲ 10 km s−1, and a turbulent (halo) component, σν ≲ 20 km s−1. Some systems show only the low velocity dispersion component.5.At least one system intervening toward a radio QSO (Pks 0458-020) shows 21-cm absorption. The system shows multiple cloud structure with σν ≈ 6 km s−1, Ts ≈ 100 K, and structure extended over several kpc on the sky.6.There is evidence that these systems may be self gravitating with scale height of the order of 300 pc.7.These systems represent a unique population of absorber (distinct from the ‘Lyman a forest’ and heavy element systems) covering approximately 20% of the sky to z ≈ 3 and accounting for all of the baryonic matter at that redshift.

scholarly journals Box/Peanut Galaxies in the Near-IR

1996 ◽  
Vol 157 ◽  
pp. 224-226
Author(s):  
S. M. Baggett ◽  
J. W. MacKenty
Keyword(s):  
Major Axis ◽  
Minor Axis ◽  
Disk Galaxies ◽  
Early Type ◽  
Contour Maps ◽  
Near Ir

Galaxies with box/peanut-shaped (b/p) bulges have been known for some time (e.g., NGC 128 and NGC 7332 (Sandage 1961)). Observationally, b/p features are detected in edge-on systems, and are visible in images, contour maps, and brightness profiles as isophote sections that near minor axis are relatively flat and parallel to major axis (see Figure 1). Peanut-type bulges have isophotes indented at the intersection with the minor axis.There have been several morphological surveys to date. The two most recent studies have found that about 20% of early-type galaxies and nearly 45% of all disk galaxies are b/p galaxies (see Shaw 1987, Dettmar 1989, and references therein) and that the b/p galaxy properties appear similar to normal spirals in the optical, radio, and infrared. A few kinematical studies have been done: b/p bulges are found to rotate more like disks than bulges (e.g., 150 km s−1 up to 6 kpc above the plane in NGC 128 (Jarvis 1990) and the velocities remain constant up to large z, implying cylindrical rotation (e.g., NGC 3079 has v constant out to 1.6 kpc (Shaw et al. 1993)).

scholarly journals Minor mergers: fundamental but unexplored drivers of galaxy evolution

2015 ◽  
Vol 11 (S319) ◽  
pp. 130-136
Author(s):  
Sugata Kaviraj
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Morphological Type ◽  
Disk Galaxies ◽  
Early Type ◽  
Gas Reservoirs ◽  
Star Formation Activity ◽  
Merger Process ◽  
Minor Mergers ◽  
Local Disk

AbstractWe use the SDSS Stripe 82 to study the stellar-mass growth that is triggered by minor mergers in local disk galaxies. Since major mergers destroy disks and create spheroids, morphologically disturbed spirals are likely remnants of minor mergers (since the disk remains intact). Disturbed spirals exhibit enhanced specific star formation rates (SSFRs), with the enhancement increasing in galaxies with ‘later’ morphological type (that have larger gas reservoirs and smaller bulges). By combining the SSFR enhancements with the fraction of time spirals in various morphological classes spend in this ‘enhanced’ mode, we estimate that ~40% of the star formation activity in local spirals is directly triggered by minor mergers. Combining our results with the star formation in local early-type galaxies – which is almost completely driven by minor mergers – suggests that around half the star formation activity at the present day is likely to be triggered by the minor-merger process.

scholarly journals Bar strengths in early-type disk galaxies

2007 ◽  
Vol 3 (S245) ◽  
pp. 131-132
Author(s):  
R. Buta ◽  
E. Laurikainen ◽  
H. Salo ◽  
J. H. Knapen ◽  
D. L. Block
Keyword(s):  
Near Infrared ◽  
Disk Galaxies ◽  
Early Type ◽  
Gravitational Torque ◽  
Current Sample ◽  
S0 Galaxies

AbstractUsing the gravitational torque indicator Qb, we derive the distribution of bar strengths for a sample of early-type disk galaxies. The sample is part of the Near-Infrared S0 Survey (NIRS0S), designed to examine the properties of bars, bulges, and disks in galaxies classified as types S0− to Sa. Although the survey is only partly finished, we find that the distribution of bar strengths in S0 galaxies differs from that in spirals by lacking an extended tail to high values of Qb. No S0 in our current sample has Qb > 0.25, while spirals extend to Qb ≈ 0.7. Bars having Qb > 0.25 first appear among S0/a to Sa galaxies.

scholarly journals Nature of bulges in the Hubble sequence

2007 ◽  
Vol 3 (S245) ◽  
pp. 309-310
Author(s):  
Eija Laurikainen ◽  
H. Salo ◽  
R. Buta ◽  
J. H. Knapen
Keyword(s):  
Star Formation ◽  
Strong Evidence ◽  
Disk Galaxies ◽  
Early Type ◽  
Late Type ◽  
Hubble Sequence

AbstractWe evaluate the nature of bulges in the Hubble sequence, based on an analysis of 216 disk galaxies of all morphological types (S0-Sd). For this purpose we collect our various analysis made separately for early and late-type galaxies, published in a series of papers. Using the criteria by Kormendy & Kennicutt we find strong evidence of pseudobulges in all Hubble types, including S0s. However, due to the relatively massive bulges in S0-S0/a galaxies it is not probable that the (pseudo)bulges in these galaxies were formed in a similar manner as in spirals. More likely, pseudobulges particularly in strongly barred early-type disk galaxies are suggested to be a combination of star formation and the nearly exponential central components of bars.

scholarly journals Molecular Gas and Star Formation in Local Early–type Galaxies

2010 ◽  
Vol 6 (S277) ◽  
pp. 55-58
Author(s):  
M. Bureau ◽  
T. A. Davis ◽  
K. Alatalo ◽  
A. F. Crocker ◽  
L. Blitz ◽  
...  
Keyword(s):  
Star Formation ◽  
Far Infrared ◽  
Gas Content ◽  
Molecular Gas ◽  
Disk Galaxies ◽  
Formation Processes ◽  
Early Type ◽  
High Detection Rate ◽  
Physical Conditions ◽  
Multi Wavelength

AbstractThe molecular gas content of local early-type galaxies is constrained and discussed in relation to their evolution. First, as part of the ATLAS3D survey, we present the first complete, large (260 objects), volume-limited single-dish survey of CO in normal local early-type galaxies. We find a surprisingly high detection rate of 22%, independent of luminosity and at best weakly dependent on environment. Second, the extent of the molecular gas is constrained with CO synthesis imaging, and a variety of morphologies is revealed. The kinematics of the molecular gas and stars are often misaligned, implying an external gas origin in over a third of the systems, although this behaviour is drastically diffferent between field and cluster environments. Third, many objects appear to be in the process of forming regular kpc-size decoupled disks, and a star formation sequence can be sketched by piecing together multi-wavelength information on the molecular gas, current star formation, and young stars. Last, early-type galaxies do not seem to systematically obey all our usual prejudices regarding star formation, following the standard Schmidt-Kennicutt law but not the far infrared-radio correlation. This may suggest a greater diversity in star formation processes than observed in disk galaxies. Using multiple molecular tracers, we are thus starting to probe the physical conditions of the cold gas in early-types.

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