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Dwarf irregulars (dIrrs) are among the most common type of galaxy in the Universe. They typically have gas-rich, low surface-brightness, metal-poor, and relatively-thick disks. Here we summarize the current state of our knowledge of the…

Astrophysics of Galaxies · Physics 2024-02-28 Deidre A. Hunter , Bruce G. Elmegreen , Suzanne C. Madden

We study the relationship between the gas column density (Sigma_HI) and the star formation rate surface density (Sigma_SFR) for a sample of extremely small (M_B ~ -13, Delta V_50 ~ 30 km/s) dwarf irregular galaxies. We find a clear…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-04 Sambit Roychowdhury , Jayaram N. Chengalur , Serafim S. Kaisin , Ayesha Begum , Igor D. Karachentsev

Images and longslit, echelle spectra of the \Ha emission from 14 dwarf galaxies and M82 have been used to identify expanding shells of ionized gas. Supershells (radius $>~300$ pc) are found in 12 of the dwarfs. The measured shell sizes and…

Astrophysics · Physics 2009-10-30 Crystal L. Martin

We have examined the stellar structure of 10 nearby, low stellar mass (10^6 to 6 x 10^7 Msolar) dwarf irregular galaxies by fitting ellipses as a function of surface brightness on ultra-deep V images. These are compared to far ultraviolet…

Astrophysics of Galaxies · Physics 2026-05-04 Deidre A. Hunter , Bruce G. Elmegreen

The expected episodic or intermittent star formation histories (SFHs) of gas rich dwarf irregular galaxies (dIrrs) are the longstanding puzzles to understand their whole evolutional history. Solving this puzzle, we should grasp what…

Astrophysics · Physics 2009-11-10 Masakazu A. R. Kobayashi , Hideyuki Kamaya

We explore how the estimated star formation rate (SFR) of a sample of isolated, massive dusty star-forming galaxies at early cosmic epochs ($1.5 < z < 3.5$) changes when their ultraviolet (UV) to near-infrared (NIR) spectral energy…

Astrophysics of Galaxies · Physics 2019-12-24 Zacharias E. Escalante , Shardha Jogee , Sydney Sherman

Spitzer Space Telescope InfraRed Array Camera (IRAC) images of M100 show numerous long filaments with regularly-spaced clumps, suggesting the associated cloud complexes formed by large-scale gravitational instabilities in shocked and…

Astrophysics of Galaxies · Physics 2018-08-15 Bruce G. Elmegreen , Debra Meloy Elmegreen , Yuri N. Efremov

We have studied multi-band surface brightness profiles of a representative sample of 34 nearby dwarf irregular galaxies (dIrrs). Our data include GALEX FUV/NUV, UBV, H\alpha, and Spitzer 3.6 \mum images. These galaxies constitute the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Hong-Xin Zhang , Deidre A. Hunter , Bruce G. Elmegreen , Yu Gao , Andreas Schruba

We have used the Spitzer Space Telescope to study the dust properties of a sample of star-forming dwarf galaxies. The differences in the mid-infrared spectral energy distributions for these galaxies which, in general, are low metallicity…

We compare the gas distribution, kinematics and the current star formation in a sample of 10 very faint (-13.37 < M_B < -9.55) dwarf galaxies. For 5 of these galaxies we present fresh, high sensitivity, GMRT HI 21cm observations. For all…

We investigate the dynamics of starbursting dwarf galaxies, using both new and archival HI observations. We consider 18 nearby galaxies that have been resolved into single stars by HST observations, providing their star formation history…

Astrophysics of Galaxies · Physics 2014-06-23 Federico Lelli , Marc Verheijen , Filippo Fraternali

Several measures of galaxy size and mass obtained from the neutral hydrogen mapping of 70 dwarf irregular galaxies presented in Paper I (Hoffman et al. 1996) are compared statistically to those for the set of all available HI-mapped dwarfs…

Astrophysics · Physics 2009-10-28 E. E. Salpeter , G. L. Hoffman

We present $^{12}$CO(1-0) and $^{12}$CO(2-1) observations of a sample of 20 star-forming dwarfs selected from the Herschel Virgo Cluster Survey, with oxygen abundances ranging from 12 + log(O/H) ~ 8.1 to 8.8. CO emission is observed in ten…

We present the results of the spectroscopic and photometric follow-up of two field galaxies that were selected as possible stellar counterparts of local high velocity clouds. Our analysis shows that the two systems are distant (D>20 Mpc)…

Astrophysics of Galaxies · Physics 2017-02-08 M. Bellazzini , V. Belokurov , L. Magrini , F. Fraternali , V. Testa , G. Beccari , A. Marchetti , R. Carini

We used multiwavelength data (HI, FUV, NUV, R) to search for evidence of star formation in the intragroup medium of the Hickson Compact Group 100. We find that young star-forming regions are located in the intergalactic HI clouds of the…

The low metallicities of dwarf irregular galaxies (dIrr) greatly influence the formation and structure of molecular clouds. These clouds, which consist primarily of H$_2$, are typically traced by CO, but low metallicity galaxies are found…

We present a Far-Ultraviolet (FUV) study of sixteen star-forming dwarf galaxies (SFDGs) using the Ultraviolet Imaging Telescope (UVIT). Morphologically, SFDGs are classified as dwarf spirals, dwarf irregulars, and blue compact dwarfs…

Astrophysics of Galaxies · Physics 2024-04-02 S Amrutha , Mousumi Das , Jyoti Yadav

We present Halpha narrow-band imaging of 17 dwarf irregular galaxies (dIs) in the nearby Centaurus A Group. Although all large galaxies of the group have a current or recent enhanced star formation episode, the dIs have normal star…

Astrophysics of Galaxies · Physics 2010-11-02 Stephanie Cote , Adam Draginda , Evan D. Skillman , Bryan W. Miller

We present uniformly measured star formation histories (SFHs) of 60 nearby (D~4Mpc) dwarf galaxies based on CMDs of resolved stellar populations from images taken with HST as part of the ACS Nearby Galaxy Survey Treasury program (ANGST).…

We study the relationship between the gas column density (derived from GMRT 21 cm data) and the star formation rate surface density (derived from publicly available GALEX data) for a sample of 23 extremely faint dwarf irregular galaxies…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-04 Sambit Roychowdhury , Jayaram N. Chengalur , Ayesha Begum , Igor D. Karachentsev