Results 21 to 30 of about 601,655 (181)
A New Culprit in the Second-Parameter Problem in the Sculptor Dwarf Spheroidal Galaxy? [PDF]
The Astrophysical Journal, 1999 Color-magnitude diagrams from deep, wide-field CCD photometry of the Sculptor dwarf spheroidal galaxy reveal that the red horizonal branch (RHB) stars are strongly concentrated towards the center of the galaxy relative to the dominant old population in Sculptor, confirming an earlier claim of such a gradient (Da Costa et al. 1996).
Eva K. Grebel +4 more
semanticscholar +6 more sources
Conversion Problems: How (Not) to Determine Molecular Masses in Dwarf Galaxies [PDF]
arXiv, 2001 The determination of molecular gas masses in star forming dwarf irregular galaxies is crucial to assess the star formation process in these objects. But the derivation of the molecular gas content of dwarf galaxies has been a long-standing problem.
S. Huettemeister
arxiv +5 more sources
CHEMICAL EVOLUTION OF THE GALAXY: THE G-DWARF PROBLEM AND RADIOACTIVE CHRONOLOGY REVISITED TAKING ACCOUNT OF THE THICK DISK [PDF]
, 2001 Thin and Thick disk metallicities overlap, but alpha(Fe) relations differ; there is also a hiatus in time before the first thin-disk stars, with a minimum metallicity [Fe/H] = -0.6. Thus there are two `G-dwarf' problems. We fit metallicity distribution functions (MDFs) for the two disks derived by Wyse & Gilmore (1995) with analytical models (for O
B. Pagel
semanticscholar +7 more sources
Distance to the nearby dwarf galaxy [TT2009] 25 in the NGC 891 group using the tip of the red giant branch [PDF]
A&A 629, L2 (2019), 2019 Dwarf galaxies are key objects for small-scale cosmological tests like the abundance problems or the planes-of-satellites problem. A crucial task is therefore to get accurate information for as many nearby dwarf galaxies as possible. Using extremely deep,
O. Müller +3 more
semanticscholar +3 more sources
The G-dwarf problem in the Galaxy [PDF]
New Astronomy, 2008 The empirical differential metallicity distribution (EDMD) is deduced for (i) local thick disk stars; (ii) likely metal-weak thick disk stars; (iii) chemically selected local G dwarfs, with the corrections performed in order to take into account the stellar scale height; in addition to previous results related to (iv) solar neighbourhood halo subdwarfs;
R. Caimmi
semanticscholar +4 more sources
Inner Halo Shapes of Dwarf Galaxies: Resolving the Cusp/Core Problem [PDF]
Symposium - International Astronomical Union, 2004 We derive inner dark matter halo density profile slopes for a sample of 200 dwarf galaxies by inverting rotation curves obtained from high-quality, long-slit optical spectra. Using simulations to assess the impact of long-slit observing and data processing errors on our measurements, we conclude that our observations are consistent with the cuspy halos
K. Spekkens, Riccardo Giovanelli
+7 more sources
The Rotation Curves of Dwarf Galaxies: A Problem for Cold Dark Matter? [PDF]
The Astrophysical Journal, 2004 We address the issue of accuracy in recovering density profiles from observations of rotation curves of galaxies. We ``observe'' and analyze our models in much the same way as observers do the real galaxies. We find that the tilted ring model analysis produces an underestimate of the central rotational velocity.
Octavio Valenzuela +4 more
+8 more sources
Formation of dwarf galaxies and small-scale problems of CDM [PDF]
Proceedings of the International Astronomical Union, 2006 AbstractThe concordance cosmological model based on cold dark matter makes definitive predictions for the growth of galaxies in the Universe, which are being actively studied using numerical simulations. These predictions appear to contradict the observations of dwarf galaxies.
Oleg Y. Gnedin
openaire +4 more sources
Is The Vast Polar Structure Of Dwarf Galaxies A Serious Problem For ΛCDM? [PDF]
Monthly Notices of the Royal Astronomical Society, 2017 14 pages, 6 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society.
Andrew Lipnicky, Sukanya Chakrabarti
openaire +3 more sources
An assessment of the “too big to fail” problem for field dwarf galaxies in view of baryonic feedback effects [PDF]
Astronomy & Astrophysics, 2016 Recent studies have established that extreme dwarf galaxies --whether satellites or field objects-- suffer from the so called "too big to fail" (TBTF) problem. Put simply, the TBTF problem consists of the fact that it is difficult to explain both the measured kinematics of dwarfs and their observed number density within the LCDM framework.
Papastergis, E., Shankar, F.
openaire +4 more sources