The structure and stellar content of globular clusters. II - Star counts and main-sequence luminosity functions for 47 Tuc, NGC 6397, and NGC 6752

1982 ◽  
Vol 87 ◽  
pp. 990 ◽  
Author(s):  
G. S. Da Costa
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Stellar Content ◽  
Luminosity Functions

HII regions and young star clusters in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 207-208
Author(s):  
Myung Gyoon Lee
Keyword(s):  
Main Sequence ◽  
Star Clusters ◽  
Hii Regions ◽  
Young Star ◽  
Magellanic Clouds ◽  
Stellar Content ◽  
Ccd Photometry ◽  
Luminosity Functions ◽  
Young Star Clusters ◽  
Mass Functions

Using U BV CCD photometry, the stellar content of HII regions and young star clusters in the Magellanic Clouds has been studied: (1) the reddenings have been determined, and ages of OB associations and young star clusters have been measured; (2) the stellar initial mass functions have been determined by using the main-sequence luminosity functions; and (3) U BV CCD surface photometry of nine young star clusters has been obtained and their structural properties investigated.

scholarly journals An Automated HR Diagram for NGC 6809 (M 55)

1988 ◽  
Vol 126 ◽  
pp. 627-628
Author(s):  
Michael J. Irwin ◽  
Virginia Trimble
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Luminosity Functions ◽  
Order Of Magnitude ◽  
Large Telescopes ◽  
Hr Diagram

For decades, star counts and HR diagrams extending below the main sequence turnoff in globular clusters meant the work of Sandage (1957). The advent of large CCD's at the foci of large telescopes has changed this (McClure et al. 1985, Harris & Hesser 1985, Christian & Heasley 1986, Heasley et al. 1986, Penny & Dickens 1986, Richer & Fahlman 1986, Smith et al. 1986) and made clear that clusters differ in the shapes of their luminosity functions and in the morphology of their HR diagrams. We return here to photographic methods, which can capture an order of magnitude more images and so possibly reveal new details.

scholarly journals Deep CCD Photometry in ω Cen and NGC 3201+

1988 ◽  
Vol 126 ◽  
pp. 629-630
Author(s):  
S. Ortolani
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Ccd Photometry ◽  
Luminosity Functions

About 30 deep B and V CCD images, obtained at the 3.6 m ESO telescope, with the EFOSC in the focal reducer option, have been used to obtain color-magnitude diagrams and luminosity functions for the main sequence of the globular clusters ω Cen and NGC 3201. Two fields per cluster, at different distances from the center (25′ − 30′ for ω Cen and 7′.5 − 9′ for NGC 3201) were observed and separately reduced.

scholarly journals Stellar Luminosity and Mass Functions of Globular Clusters

1996 ◽  
Vol 174 ◽  
pp. 71-80 ◽  
Author(s):  
Giampaolo Piotto ◽  
Adrienne M. Cool ◽  
Ivan R. King
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Mass Range ◽  
Theoretical Limit ◽  
Low Mass Stars ◽  
Luminosity Functions ◽  
Hydrogen Ignition ◽  
Low Mass ◽  
First Time ◽  
Mass Functions

HST makes it possible for the first time to study nearly the entire mass range of globular-cluster main sequences, from the turnoff down almost to the theoretical limit for hydrogen ignition. We present main-sequence luminosity functions (LFs) for four clusters that include stars with M < 0.15M⊙ in all cases. We compare these and other LFs that have been obtained with HST for a total of five globulars to date. Two of the three clusters in the sample that have similar metallicities have nearly identical LFs, while the third is relatively deficient in low mass stars. Possible implications of this finding are briefly discussed. Inferred mass functions vary significantly depending on the mass-luminosity relations that are adopted.

New Main-Sequence Luminosity Functions for Globular Clusters

1988 ◽  
pp. 485-486
Author(s):  
Robert D. McClure ◽  
Peter B. Stetson ◽  
James E. Hesser ◽  
Graham H. Smith ◽  
William E. Harris ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Luminosity Functions

scholarly journals Luminosity Function of Old Globular Clusters in the SMC

1984 ◽  
Vol 78 ◽  
pp. 359-361
Author(s):  
M. Kontizas ◽  
E. Kontizas
Keyword(s):  
Globular Clusters ◽  
Luminosity Function ◽  
Star Cluster ◽  
Stellar Content ◽  
Luminosity Functions

Luminosity Functions (LFs) provide useful information on the stellar content of a star cluster. One of the problems of studying the colour-magnitude (c-m) diagrams in remote clusters is the contamination of cluster members with field stars. If all the stars of a cluster are measured in concentric rings one can reach the field and compare the c-m diagram of the field with that of the central areas. For the SMC where the field and cluster areas seem to have similar c-m diagrams, this method is not always useful and then the LF becomes an important tool of overcoming this obstacle.

scholarly journals New Main-Sequence Luminosity Functions for Globular Clusters

1988 ◽  
Vol 126 ◽  
pp. 485-486
Author(s):  
Robert D. McClure ◽  
Peter B. Stetson ◽  
James E. Hesser ◽  
Graham H. Smith ◽  
William E. Harris ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Ccd Cameras ◽  
Ccd Photometry ◽  
The Past ◽  
Function Fitting ◽  
Point Spread ◽  
Luminosity Functions ◽  
Wide Range ◽  
Spread Function

We report new results from a program which is aimed at obtaining deep CCD photometry for a sample of relatively nearby globular clusters having a wide range of metallicities. The CCD cameras on the CFHT 3.6 m, CTIO 4 m and KPNO 4 m telescopes have been used over the past 4 years to obtain deep exposures in regions of a number of clusters. In order to avoid the severest crowding, all of our observations have been obtained at distances of greater than ~ 5 core radii from the cluster centers. The images have been analysed by using the DAOPHOT point-spread-function fitting routines.

scholarly journals Dynamical Masses and Mass-to-Light Ratios for Globular Clusters

1975 ◽  
Vol 69 ◽  
pp. 151-157
Author(s):  
G. Illingworth
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Large Fraction ◽  
Low Mass Stars ◽  
Luminosity Functions ◽  
Low Mass ◽  
Dynamical Masses

Dynamical masses have been determined for 10 globular clusters. Comparison of the dynamically determined M/L values with those calculated from extrapolations of the observed upper main sequence/giant branch luminosity functions for M3 and M5 indicate that low mass stars (∼0.2 M⊙) comprise a large fraction of the total number.

Luminosity Functions for Globular Clusters

1998 ◽  
Vol 509 (1) ◽  
pp. 192-202 ◽  
Author(s):  
Fabio Silvestri ◽  
Paolo Ventura ◽  
Francesca D'Antona ◽  
Italo Mazzitelli
Keyword(s):  
Globular Clusters ◽  
Luminosity Functions

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.

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