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The pressures of giant HII regions in 6 dwarf Irregular galaxies are a factor of ~10 larger than the average pressures of the corresponding galaxy disks, obtained from the stellar and gaseous column densities. Either the visible HII regions…

Astrophysics · Physics 2009-10-31 B. G. Elmegreen , D. A. Hunter

The parameters of the ionized gas in NGC 6946 (in the [NII]6548,6583, H-alpha and [SII]6717,6731 lines) are investigated with the SAO RAS BTA telescope along three positions of the long slit of the SCORPIO focal reducer, passing through a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Yu. N. Efremov , V. L. Afanasiev , O. V. Egorov

Ionized interstellar gas is an important component of the interstellar medium and its lifecycle. The recent evidence for a widely distributed highly ionized warm interstellar gas with a density intermediate between the warm ionized medium…

Astrophysics of Galaxies · Physics 2021-07-14 W. D. Langer , J. L. Pineda , P. F. Goldsmith , E. T. Chambers , D. Riquelme , L. D. Anderson , M. Luisi , M. Justen , C. Buchbender

We present results from GMRT HI 21 cm line observations of the interacting galaxy pair Arp 181 (NGC 3212 and NGC 3215) at z =0.032. We find almost all of the detected HI (90%) displaced well beyond the optical disks of the pair with the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Chandreyee Sengupta , K. S. Dwarakanath , D. J. Saikia , T. C. Scott

The Green Bank Telescope (GBT) Diffuse Ionized Gas Survey (GDIGS) is a fully-sampled radio recombination line (RRL) survey of the inner Galaxy at C-band (4-8 GHz). We average together ~15 Hn$\alpha$ RRLs within the receiver bandpass to…

Astrophysics of Galaxies · Physics 2020-02-12 Matteo Luisi , L. D. Anderson , Bin Liu , Dana S. Balser , T. M. Bania , Trey V. Wenger , L. M. Haffner

(Abridged) We present Herschel/HIFI spectra of the H2O 1113 GHz and H2O+ 1115 GHz lines toward five nearby prototypical starburst/AGN systems, and OH+ 971 GHz spectra toward three of these. The beam size of 20" corresponds to resolutions…

Astrophysics of Galaxies · Physics 2016-09-14 Floris van der Tak , Axel Weiss , Lijie Liu , Rolf Guesten

We present deep narrowband observations with high spatial resolution of extraplanar diffuse ionized gas in the halo of NGC891, obtained with the WFPC2 on-board the HST. Our H-alpha observations, centered on the northern part of NGC891,…

Astrophysics · Physics 2009-11-10 Joern Rossa , Ralf-Juergen Dettmar , Rene A. M. Walterbos , Colin A. Norman

Optical red spectra of a set of 18 bright barred spiral galaxies are presented. The study is aimed at determining the local kinematics, and the physical conditions of ionized gas in the compact nucleus (inside a diameter of 5") and in the…

Astrophysics · Physics 2007-05-23 J. A. Garcia-Barreto , H. Aceves , O. Kuhn , G. Canalizo , R. Carrillo , J. Franco

Far-infrared spectroscopy obtained with the ISO LWS has shown that there is strong variation (more than 2 orders of magnitude) in the [C II]/FIR ratios in galaxies extending from blue compact dwarfs, to normal and starburst galaxies, down…

Astrophysics · Physics 2007-05-23 Jacqueline Fischer

We present the first results of an ongoing project to investigate the present-day chemical abundances of the extreme outer parts of galactic disks, as probed by the emission line spectra of a new sample of HII regions. The galaxies studied…

Astrophysics · Physics 2009-10-30 Annette M. N. Ferguson , Jay Gallagher , Rosemary F. G. Wyse

The accepted explanation of the observed dichotomy of two orders of magnitude between in situ measurements of electron density in HII regions, derived from emission line ratios, and average measurements based on integrated emission measure,…

Astrophysics · Physics 2016-08-16 C. Giammanco , J. E. Beckman , A. Zurita , M. Relaño

We report the detection of the Diffuse Interstellar Bands (``$DIBs$'') in the optical spectra of seven far-infrared-selected starburst galaxies. The $\lambda$6283.9 \AA and $\lambda$ 5780.5 \AA features are detected with equivalent widths…

Astrophysics · Physics 2009-10-31 Timothy M. Heckman , Matthew D. Lehnert

NGC 6822 is an isolated dwarf irregular galaxy in the local group at a distance of 490 kpc. In this paper, we present the star formation history (SFH) within a field with a radius of 3 kpc, beyond the optical body of the galaxy (1.2 kpc).…

Astrophysics of Galaxies · Physics 2025-01-28 Fatemeh Khatamsaz , Mahdi Abdollahi , Hedieh Abdollahi , Atefeh Javadi , Jacco Th. van Loon

We present spectra obtained with the 10.4 m Gran Telescopio Canarias telescope of 13 Galactic HII regions, most of them of very low ionisation degree. The objects are located along the Galactic disc, with R_G from 5.7 to 16.1 kpc. We…

Astrophysics of Galaxies · Physics 2018-05-16 C. Esteban , J. Garcia-Rojas

We investigate the ionization mechanisms for hidden broad-line region (HBLR) and non-HBLR Seyfert 2 galaxies by comparing some optical emission line ratios. We note that the [N II]6583/H_alpha ratio of the non-HBLR Seyfert 2 galaxies is…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Po-Chieh Yu , Chorng-Yuan Hwang

We present Integral Field Spectroscopy (IFS) of NGC 595, one of the most luminous HII regions in M33. This type of observations allows studying the variation of the principal emission-line ratios across the surface of the nebula. At each…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 M. Relano , A. Monreal-Ibero , J. M. Vilchez , R. C. Kennicutt

We constructed diagnostic diagrams using emission line ratios and equivalent widths observed in several samples of HII galaxies. The diagrams are compared to predictions from new photoionization models for evolving starbursts. We find that…

Astrophysics · Physics 2009-11-06 Grazyna Stasinska , Daniel Schaerer , Claus Leitherer

We present VLA measurements of H92alpha radio recombination line emission from an unusual HII region G0.18--0.04, the ``Sickle'', with spatial and spectral resolutions of 27" times 24".9 and 14 km/s, respectively. These observations…

Astrophysics · Physics 2015-06-24 F. Yusef-Zadeh , D. A. Roberts , M. Wardle

The [NII] 122 and 205 \mu m transitions are powerful tracers of the ionized gas in the interstellar medium. By combining data from 21 galaxies selected from the Herschel KINGFISH and Beyond the Peak surveys, we have compiled 141 spatially…

The understating of the origin of the H2 line emission from the central regions of galaxies represent an important key to improve our knowledge about the excitation and ionization conditions of the gas in these locations. Usually these…

Astrophysics of Galaxies · Physics 2016-05-25 Gabriele S. Ilha , Marina Bianchin , R. A. Riffel