Results 61 to 70 of about 12,211 (252)

The Interstellar Medium in Dwarf Irregular Galaxies

Annual Review of Astronomy and Astrophysics
Dwarf irregular (dIrr) galaxies 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 interstellar medium (ISM), including atomic, molecular, and ionized gas, along with their dust properties and
Hunter, Deidre A., Elmegreen, Bruce G., Madden, Suzanne C.   +2 more
openaire   +3 more sources

The Early Chemical Evolution of Dwarf Irregular Galaxies [PDF]

Highlights of Astronomy, 2005
AbstractInvestigations have been performed to understand the age of dwarf irregular galaxies from the point of view of their presently low chemical abundances and the enhanced star-formation rate. While for a few objects, like e.g. I Zw 18, their assumed relative youth can be verified by models taking a double-starburst behavior into account, those ...
Andreas Rieschick, Joachim Köppen, Simone Recchi, Gerhard Hensler   +3 more
openaire   +3 more sources

Chemical and Photometric Evolution Models for Disk, Irregular, and Low Mass Galaxies

Advances in Astronomy, Volume 2014, Issue 1, 2014., 2014
We summarize the updated set of multiphase chemical evolution models performed with 44 theoretical radial mass initial distributions and 10 possible values of efficiencies to form molecular clouds and stars. We present the results about the infall rate histories, the formation of the disk, and the evolution of the radial distributions of diffuse and ...
Mercedes Mollá, Jorge Iglesias Páramo
wiley   +1 more source

The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. V. The Star Formation History of Sagittarius Dwarf Irregular Galaxy Derived from Long-period Variable Stars

The Astrophysical Journal, 2023
We conducted an optical monitoring survey of the Sagittarius dwarf irregular galaxy (SagDIG) during the period of 2016 June–2017 October, using the 2.5 m Isaac Newton Telescopeat La Palama.
Tahere Parto, Shahrzad Dehghani, Atefeh Javadi, Elham Saremi, Jacco Th. van Loon, Habib G. Khosroshahi, Iain McDonald, Mohammad T. Mirtorabi, Mahdieh Navabi, Maryam Saberi   +9 more
doaj   +1 more source

First Stellar Abundances in the Dwarf Irregular Galaxy Sextans A [PDF]

The Astronomical Journal, 2004
We present the abundance analyses of three isolated A-type supergiant stars in the dwarf irregular galaxy Sextans A from high-resolution spectra the UVES spectrograph at the VLT. Detailed model atmosphere analyses have been used to determine the stellar atmospheric parameters and the elemental abundances of the stars.
Christophe Pinte, Eline Tolstoy, Rolf-Peter Kudritzki, Andreas Kaufer, Kim A. Venn   +4 more
openaire   +4 more sources

100 Proof: H i Observations of 100 Nearby Dwarf Galaxies with the 100 m Green Bank Telescope

The Astronomical Journal
We describe the results of observations with the 100 m Robert C. Byrd Green Bank Telescope in the H i line of 105 nearby dwarf galaxies, 60 of which were discovered recently in the DESI Legacy Imaging Surveys.
Aleksandra E. Nazarova, John M. Cannon, Igor D. Karachentsev, Dmitry I. Makarov, Maksim I. Chazov, Lila Schisgal, William St. John   +6 more
doaj   +1 more source

Stellar Abundances in Dwarf Irregular Galaxies

, 2003
Dwarf irregular galaxies appear to have undergone very slow chemical evolution since they have low nebular abundances, but have had ongoing star formation over the past 15 Gyr. They are too distant for red giant abundance analyses to examine the details of their chemical evolution, however the isolated, bright blue supergiants do allow us to determine ...
Venn, K.A., Tolstoy, E., Kaufer, A., Kudritzki, R.P.   +3 more
openaire   +3 more sources

Oxygen and Nitrogen in Isolated Dwarf Irregular Galaxies

The Astrophysical Journal, 2006
We present long slit optical spectroscopy of 67 HII regions in 21 dwarf irregular galaxies to investigate the enrichment of oxygen, nitrogen, neon, sulfur, and argon in low mass galaxies. Oxygen abundances are obtained via direct detection of the temperature sensitive emission lines for 25 HII regions; for the remainder of the sample, oxygen abundances
Liese van Zee, Martha P. Haynes
openaire   +3 more sources

AT 2017fvz: a nova in the dwarf irregular galaxy NGC 6822 [PDF]

Monthly Notices of the Royal Astronomical Society, 2019
ABSTRACT A transient in the Local Group dwarf irregular galaxy NGC 6822 (Barnard’s Galaxy) was discovered on 2017 August 2 and is only the second classical nova discovered in that galaxy. We conducted optical, near-ultraviolet, and X-ray follow-up observations of the eruption, the results of which we present here.
W Zheng, S C Williams, K L Page, P A James, J C Hestenes, M Henze, A V Filippenko, C M Copperwheat, M J Darnley, M W Healy   +9 more
openaire   +5 more sources

Leaf Anatomy and Photochemical Behaviour of Solanum lycopersicum L. Plants from Seeds Irradiated with Low‐LET Ionising Radiation

The Scientific World Journal, Volume 2014, Issue 1, 2014., 2014
Plants can be exposed to ionising radiation not only in Space but also on Earth, due to specific technological applications or after nuclear disasters. The response of plants to ionising radiation depends on radiation quality/quantity and/or plant characteristics. In this paper, we analyse some growth traits, leaf anatomy, and ecophysiological features
V. De Micco, R. Paradiso, G. Aronne, S. De Pascale, M. Quarto, C. Arena, Charles Hocart   +6 more
wiley   +1 more source