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Atomic Hydrogen (HI) is a useful tracer of gas in and around galaxies, and can be found in extended disk-like structures well beyond a system's optical extent. Here we investigate the properties of extended HI disks that emerge in six Milky…

The scatter in global atomic hydrogen (HI) scaling relations is partly attributed to differences in how HI and stellar properties are measured, with HI reservoirs typically extending beyond the inner regions of galaxies where star formation…

We use the Illustris Simulations to gain insight into the build-up of the outer, low-surface brightness regions which surround galaxies. We characterize the stellar haloes by means of the logarithmic slope of the spherically-averaged…

The neutral atomic hydrogen (HI) mass function (HIMF) describes the distribution of the HI content of galaxies at any epoch; its evolution provides an important probe of models of galaxy formation and evolution. Here, we report Giant…

Astrophysics of Galaxies · Physics 2022-11-30 Apurba Bera , Nissim Kanekar , Jayaram N. Chengalur , Jasjeet S. Bagla

The neutral hydrogen line profiles along the major axis of the nearby spiral galaxy NGC 2403 show a wing towards the sytemic velocity. This asymmetry can be explained with the presence of an abnormally thick HI disk (FWHM ~ 5 kpc) or with a…

Astrophysics · Physics 2007-05-23 W. E. Schaap , R. Sancisi , R. A. Swaters

We report a detailed analysis of all regions of current star formation in the walls of the supergiant HI shell (SGS) in the galaxy Holmberg II based on observations with a scanning Fabry-Perot interferometer at the 6-m SAO RAS telescope. We…

Astrophysics of Galaxies · Physics 2016-11-30 Oleg V. Egorov , Tatiana A. Lozinskaya , Alexei V. Moiseev , Yuri A. Shchekinov

Context. Outflows powered by the injection of kinetic energy from massive stars can strongly affect the chemical evolution of galaxies, in particular of dwarf galaxies, as their lower gravitational potentials enhance the chance of a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 J. van Eymeren , M. Marcelin , B. S. Koribalski , R. -J. Dettmar , D. J. Bomans , J. -L. Gach , P. Balard

We present a catalog of holes and shells in the neutral atomic hydrogen (\HI) of 41 gas-rich dwarf galaxies in LITTLE THINGS (Local Irregulars That Trace Luminosity Extremes, The \HI Nearby Galaxy Survey). We analyzed their properties as…

Astrophysics of Galaxies · Physics 2020-07-22 Nau Raj Pokhrel , Caroline E. Simpson , Ioannis Bagetakos

A catalog of ionized gas velocity fields for a sample of 30 spiral and irregular galaxies of the Virgo cluster has been obtained by using three-dimensional optical data. The aim of this survey is to study the influence of high density…

We perform numerical hydrodynamic modeling of various physical processes that can form an HI ring as is observed in Holmberg I. Three energetic mechanisms are considered: multiple supernova explosions (SNe), a hypernova explosion associated…

Astrophysics · Physics 2009-11-10 E. I. Vorobyov , Shantanu Basu

Early-type galaxies (ETGs) are observed to be more compact, on average, at $z \gtrsim 2$ than at $z\simeq 0$, at fixed stellar mass. Recent observational works suggest that such size evolution could reflect the similar evolution of the host…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Lorenzo Posti , Carlo Nipoti , Massimo Stiavelli , Luca Ciotti

We present a new scenario in which massive intragroup HI clouds are the high-density parts of large HI rings/arcs formed by dynamical interaction between galaxy groups and gas-rich, low surface brightness (LSB) galaxies with extended gas…

Astrophysics · Physics 2009-11-10 K. Bekki , B. S. Koribalski , S. D. Ryder , W. J. Couch

We present the properties of 8 star-forming regions, or 'clumps,' in 3 galaxies at z~1.3 from the WiggleZ Dark Energy Survey, which are resolved with the OSIRIS integral field spectrograph. Within turbulent discs, \sigma~90 km/s, clumps are…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Emily Wisnioski , Karl Glazebrook , Chris Blake , Gregory B. Poole , Andrew W. Green , Ted Wyder , Chris Martin

We use the IRAM HERACLES survey to study CO emission from 33 nearby spiral galaxies down to very low intensities. Using atomic hydrogen (HI) data, mostly from THINGS, we predict the local mean CO velocity from the mean HI velocity. By…

We present the results of Halpha imaging of 94 irregular galaxies, including types Im, BCD, and Sm. The sample spans a large range in galactic parameters including integrated absolute magnitude (MV=-9 to -19), average surface brightness (20…

Astrophysics · Physics 2008-11-26 Deidre A. Hunter , Bruce G. Elmegreen

We use the observed sizes and star formation rates of Lyman-break galaxies (LBGs) to understand their properties expected in the hierarchical scenario of galaxy formation. The observed size distribution constrains the masses of the host…

Astrophysics · Physics 2009-11-06 Chenggang Shu , Shude Mao , H. J. Mo

We present a statistical study of the properties of diffuse HI in ten nearby galaxies, comparing the HI detected by the single-dish telescope FAST (FEASTS program) and the interferometer VLA (THINGS program), respectively. The THINGS'…

Large HII regions, with angular dimensions exceeding 10 pc, usually enclose numerous massive O-stars. Stellar winds from such stars are expected to play a sizeable role in the dynamical, morphological and chemical evolution of the targeted…

Astrophysics of Galaxies · Physics 2015-06-03 Dominic Lagrois , Gilles Joncas , Laurent Drissen

When present, extended disks of neutral hydrogen around spiral galaxies show a remarkably uniform velocity dispersion of approx 6 km/s. Since stellar winds and supernovae are largely absent in such regions, neither the magnitude nor the…

Astrophysics · Physics 2009-10-30 J. A. Sellwood , S. A. Balbus

We combine several surveys at different wavelengths with intermediate-band $ uvby\beta$ photometry to examine the correlation between the location of the OB-stars in the Centaurus star-forming field and the neutral and ionized material in…

Astrophysics of Galaxies · Physics 2013-07-17 N. Kaltcheva , V. Golev