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Integrated K-band spectra of old and intermediate-age globular clusters in the Large Magellanic Cloud
Current stellar population models have arguably the largestuncertainties in the near-IR wavelength range, partly due to a lack oflarge and well calibrated empirical spectral libraries. In this paper wepresent a project whose aim it is to provide the first library ofluminosity weighted integrated near-IR spectra of globular clusters tobe used to test the current stellar population models and serve ascalibrators for future ones. Our pilot study presents spatiallyintegrated K-band spectra of three old (?10 Gyr) and metal poor([Fe/H] ~ -1.4), and three intermediate age (1-2 Gyr) and more metalrich ([Fe/H] ~ - 0.4) globular clusters in the LMC. We measured the linestrengths of the Na I, Ca I and 12CO (2-0) absorptionfeatures. The Na I index decreases with increasing age and decreasingmetallicity of the clusters. The DCO index, used to measurethe 12CO (2-0) line strength, is significantly reduced by thepresence of carbon-rich TP-AGB stars in the globular clusters with age~1 Gyr. This is in contradiction to the predictions of the stellarpopulation models of Maraston (2005, MNRAS, 362, 799). We find that thisdisagreement is due to the different CO absorption strength ofcarbon-rich Milky Way TP-AGB stars used in the models and the LMC carbonstars in our sample. For globular clusters with age ? 2 Gyr we findDCO index measurements consistent with the model predictions.Based on observation collected at the ESO Paranal La Silla Observatory,Chile, Prog. ID 078.B-0205.Spectra in FITS format are only available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/510/A19
| UBV photometry of galactic foreground and LMC member stars. I - Galactic foreground stars
UBV photometry of 955 galactic foreground stars in the direction to theLarge Magellanic Cloud is presented. The stars have been chosen fromforeground star catalogs and have been measured to complete a new database containing entries of more than 5000 stars in the direction of theLMC. First and second order extinction coefficients at La Silla/Chileare given, which differ from the standard values because of the 1991eruption of the volcano Mt. Pinatubo.
| Positional reference stars in the Magellanic Clouds
The equatorial coordinates are determined of 926 stars (mainly ofgalactic origin) in the direction of the Magellanic Clouds at the meanepoch T = 1978.4 with an overall accuracy characterized by the meanvalues of the O-C coordinates, Sa = 0.35 arcsec and Sd = 0.38 arcsec,calculated from the coordinates of the Perth reference stars. Thesevalues are larger than the accuracy expected for primary standard stars.They allow the new positions to be considered as those of reliablesecondary standard stars. The published positions correspond to anunquestionable improvement of the quality of the coordinates provided inthe current catalogs. This study represents an 'astrometric step' in thestarting of a 'Durchmusterung' of the Magellanic Clouds organized by deBoer (1988, 1989).
| Radial velocities from objective-prism plates in the direction of the Large Magellanic Cloud. List of 398 stars, LMC members. List of 1434 galactic stars, in the LMC direction
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...13..173F&db_key=AST
| Polarization measurements of stars in the Magellanic Clouds.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..778M&db_key=AST
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | דג זהב |
| התרוממות ימנית: | 05h54m56.97s |
| סירוב: | -65°53'00.7" |
| גודל גלוי: | 7.916 |
| מרחק: | 292.398 פארסק |
| תנועה נכונה: | -3.7 |
| תנועה נכונה: | 25.4 |
| B-T magnitude: | 7.897 |
| V-T magnitude: | 7.915 |
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