scholarly journals Local Group Galaxies in the Infrared

2010 ◽  
Vol 6 (S277) ◽  
pp. 34-36
Author(s):  
John Menzies
Keyword(s):  
South African ◽  
Local Group ◽  
Magellanic Clouds ◽  
Mira Variables ◽  
Dwarf Spheroidals ◽  
Distance Indicators ◽  
Infrared Survey

AbstractA survey has been conducted of Local Group galaxies with the Japanese/South African Infrared Survey Facility at SAAO, Sutherland. A number of Mira variables have been discovered in four dwarf spheroidals, which provides an opportunity to test the usefulness of these stars as distance indicators in galaxies beyond the Magellanic Clouds. These Miras are found to follow the same period-luminosity relation as in the LMC, provided bolometric magnitudes are used.

scholarly journals Surveys for Carbon Stars in External Galaxies

2000 ◽  
Vol 177 ◽  
pp. 51-58
Author(s):  
Marc Azzopardi
Keyword(s):  
Local Group ◽  
Galactic Halo ◽  
Magellanic Clouds ◽  
Carbon Stars ◽  
Molecular Absorption ◽  
Absorption Bands ◽  
Distant Galaxies ◽  
External Galaxies ◽  
Dwarf Spheroidals

Prominent molecular absorption bands in the spectra of carbon stars make their detection possible, even in relatively distant external galaxies. Although extensive surveys for carbon stars have been carried out mainly in the Magellanic Clouds and the dwarf spheroidals in the Galactic halo, more distant galaxies in the Local Group and beyond have been successfully searched for this kind of object.

scholarly journals Eclipsing Binaries: Tools for Calibrating the Extragalactic Distance Scale

2006 ◽  
Vol 2 (S240) ◽  
pp. 79-87 ◽  
Author(s):  
Alceste Z. Bonanos
Keyword(s):  
Local Group ◽  
Hubble Constant ◽  
Magellanic Clouds ◽  
Distance Scale ◽  
Eclipsing Binaries ◽  
Fundamental Parameters ◽  
Andromeda Galaxy ◽  
Formation And Evolution ◽  
Extragalactic Distance Scale ◽  
Distance Indicators

AbstractIn the last decade, over 7000 eclipsing binaries have been discovered in the Local Group through various variability surveys. Measuring fundamental parameters of these eclipsing binaries has become feasible with 8 meter class telescopes, making it possible to use eclipsing binaries as distance indicators. Distances with eclipsing binaries provide an independent method for calibrating the extragalactic distance scale and thus determining the Hubble constant. This method has been used for determining distances to eclipsing binaries in the Magellanic Clouds and the Andromeda Galaxy and most recently to a detached eclipsing binary in the Triangulum Galaxy by the DIRECT Project. The increasing number of eclipsing binaries found by microlensing and variability surveys also provide a rich database for advancing our understanding of star formation and evolution.

scholarly journals Discovery of Infrared Stars in Globular Clusters in the Magellanic Clouds and Their Light Variations

1998 ◽  
Vol 11 (1) ◽  
pp. 395-395
Author(s):  
S. Nishida ◽  
T. Tanabé ◽  
S. Matsumoto ◽  
T. Onaka ◽  
Y. Nakada ◽  
...  
Keyword(s):  
Mass Loss ◽  
Globular Clusters ◽  
Main Sequence ◽  
Near Infrared ◽  
Magellanic Clouds ◽  
Infrared Light ◽  
Agb Stars ◽  
Dust Shells ◽  
Infrared Stars ◽  
Infrared Survey

A systematic near-infrared survey was made for globular clusters in the Magellanic Clouds. Two infrared stars were discovered in NGC419 (SMC) and NGC1783 (LMC). NGC419 and NGC1783 are well-studied rich globular clusters whose turn-off masses and ages are estimated MTO ~ 2.0 Mʘ and т ~1.2 Gyr for NGC419, and MT0 ~ 2.0 Mʘ and т ʘ 0.9 Gyr for NGC1783, respectively. The periods of the infrared light variations were determined to be 540 dfor NGC419IR1 and to be 480 d for NGC1783IR1, respectively. Comparison of the measurements with the period—if magnitude relation for carbon Miras in the LMC by Groenewegen and Whitelock(1996) revealed that the Kmagnitudes of the infrared stars were fainter by about 0.3 — 0.8 magnitude than those predicted by the P — K relation. This deviation can be explained if the infrared stars are surrounded by thick dust shells and are obscured even in the K band. The positions of NGC419IR1and NGC1783IR1 on the P — K diagram suggest that AGB stars with the main sequence masses of about 2 Mʘ start their heavy mass-loss when P ʘ 500 d.

scholarly journals The importance of tides for the Local Group dwarf spheroidals

2006 ◽  
Vol 367 (1) ◽  
pp. 387-399 ◽  
Author(s):  
J. I. Read ◽  
M. I. Wilkinson ◽  
N. W. Evans ◽  
G. Gilmore ◽  
J. T. Kleyna
Keyword(s):  
Local Group ◽  
Dwarf Spheroidals

scholarly journals THE SIGNATURE OF GALACTIC TIDES IN LOCAL GROUP DWARF SPHEROIDALS

2009 ◽  
Vol 698 (1) ◽  
pp. 222-232 ◽  
Author(s):  
Jorge Peñarrubia ◽  
Julio F. Navarro ◽  
Alan W. McConnachie ◽  
Nicolas F. Martin
Keyword(s):  
Local Group ◽  
Dwarf Spheroidals

scholarly journals Distance Indicators in the Magellanic Clouds

1983 ◽  
Vol 6 ◽  
pp. 209-216 ◽  
Author(s):  
J.A. Graham
Keyword(s):  
Chemical Evolution ◽  
Comparative Studies ◽  
Hubble Constant ◽  
Magellanic Clouds ◽  
Distance Scale ◽  
Stellar Systems ◽  
Age Range ◽  
Distance Indicators ◽  
The Universe

In talking about the overall distance scale of the Universe and the Hubble Constant, the Magellanic Clouds are good places to start. They are stellar systems large enough to contain stars, clusters and nebulae of all types, covering a wide age range. With modern telescopes and detectors, we are able to observe stars from the very bright down to those fainter intrinsically than our own Sun. From comparative studies, we may thus establish our basic calibrations of bright objects before moving out to measure the Universe at large. At the same time, the fact that both Magellanic Clouds are independently evolving galaxies, enables us to separate the effects of stellar age and chemical evolution on the calibrations that we make.

scholarly journals RR Lyrae stars: prime calibrators of the first rung of the distance ladder

2012 ◽  
Vol 8 (S289) ◽  
pp. 101-108 ◽  
Author(s):  
Carla Cacciari
Keyword(s):  
Local Group ◽  
Primary Standard ◽  
Empirical Methods ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
The Galaxy ◽  
Definition Of ◽  
Near Future ◽  
Lyrae Stars ◽  
Distance Indicators

AbstractRR Lyrae variables are the primary standard candles for old stellar populations, and the traditional first step in the definition of the distance scale. Their properties are known on the basis of well-established physical concepts and their calibration is based on several empirical methods. Both aspects are critically reviewed, and their application as distance indicators within the Galaxy and the Local Group are discussed, also in view of the observing facilities that will be available in the near future.

Visual and Near-Infrared Photometry of Nearby Dwarf Spheroidals

1999 ◽  
Vol 192 ◽  
pp. 455-458 ◽  
Author(s):  
F. Kerschbaum ◽  
W. Nowotny ◽  
J. Hron ◽  
M. Schultheis
Keyword(s):  
Near Infrared ◽  
Broad Band ◽  
Feasibility Studies ◽  
Asymptotic Giant Branch ◽  
Agb Stars ◽  
Faint Object ◽  
Nearby Galaxies ◽  
Dwarf Spheroidals ◽  
Faint Object Spectrograph ◽  
Infrared Survey

This paper is based on photometry from two different observational approaches. Both are of an explorative character and act as feasibility studies. For the future we plan to use these methods to study Asymptotic Giant Branch (AGB) stars in nearby galaxies.First, we present results on broad-band photometry in Bessell V and I, as well as narrow-band measurements in the Wing 778 nm and 812 nm filters of a galactic globular cluster using the new Austrian Oe-FOSC (Oesterreich Faint Object Spectrograph and Camera), a copy of the ESO Instrument EFOSC mounted on our 1.5 m-telescope.The second part of the contribution deals with the possibilities of using Gunn I, J and KS measurements originating from the DENIS (DEep Near Infrared Survey of the Southern Sky) project on similar objects. A few southern dwarf spheroidals already observed within DENIS (covering now some 40% of the southern hemisphere) are selected.

scholarly journals Period Changes in Magellanic Cloud Cepheids

1984 ◽  
Vol 108 ◽  
pp. 227-228
Author(s):  
H. Deasy ◽  
P. A. Wayman
Keyword(s):  
South African ◽  
Variable Stars ◽  
Period Change ◽  
Magellanic Clouds ◽  
Rate Of Change ◽  
Data Sets ◽  
Fractional Change ◽  
Rates Of Change ◽  
Observatory Data ◽  
Irregular Period

It has been found possible to obtain information on period change in data on 115 cepheid variable stars in the Magellanic Clouds (84 LMC cepheids and 31 SMC cepheids). Harvard Observatory data of the period 1910 to 1950 (collated by Payne-Gaposchkin and Gaposchkin) are combined with Dunsink Observatory observations carried out by C.J. Butler in 1966/67 and with South African Astronomical Observatory observations covering the years 1975–1977 by Martin, Thomas, Carter and Davies to derive mean periods for the intervals between the various data sets. Using these new periods in conjunction with the very accurate Harvard periods, seperate estimates of the time averaged fractional change of period per day, d/dt (ln P), with corresponding estimated errors, could be evaluated for two epochs, one around 1950 and the other around 1971. It was found that 70 stars give rates of change of period that are not significantly different from zero, that 20 stars have two values of rate of change of period that are in agreement at the two epochs (indicative of secular period change), while 22 stars give two disparate values of rate of change of period (indicative of irregular period changes).

scholarly journals The Tidal Evolution of Local Group Dwarf Spheroidals

2008 ◽  
Vol 673 (1) ◽  
pp. 226-240 ◽  
Author(s):  
Jorge Penarrubia ◽  
Julio F. Navarro ◽  
Alan W. McConnachie
Keyword(s):  
Local Group ◽  
Tidal Evolution ◽  
Dwarf Spheroidals
Sign in / Sign up

Export Citation Format

Share Document