Horizontal-Branch Morphology as an Age Indicator
نویسندگان
چکیده
We present our recent revision of model constructions for the horizontal-branch (HB) morphology of globular clusters, which suggests the HB morphology is more sensitive to age compared to our earlier models. We also present our high precision CCD photometry for the classic second parameter pair M3 and M13. The relative age dating based on this photometry indicates that M13 is indeed older than M3 by 1.7 Gyr. This is consistent with the age difference predicted from our new models, which provides a further support that the HB morphology is a reliable age indicator in most population II stellar systems.
منابع مشابه
ar X iv : a st ro - p h / 96 06 10 8 v 1 1 8 Ju n 19 96 Horizontal Branch Morphology and the 2 nd Parameter Problem
We review the most outstanding issues related to the study of the morphology of the Horizontal Branch (HB) in the Color–Magnitude Diagrams of Galactic Globular Clusters and its use as age indicator. It is definitely demonstrated (see also Bolte, this meeting) that age cannot be the only 2nd-P driving the HB morphology. Other candidate 2nd-Ps are briefly examined, with special attention to the p...
متن کاملThe Hβ Index as an Age Indicator of Old Stellar Systems : the Effects of Horizontal-branch Stars
The strength of the Hβ index has been computed for the integrated spectra of model globular clusters from the evolutionary population synthesis. These models take into account, for the first time, the detailed systematic variation of horizontal-branch (HB) morphology with age and metallicity. Our models show that the Hβ index is significantly affected by the presence of blue HB stars. Because o...
متن کاملLyrae variables in Galactic globular clusters IV . Synthetic HB and RR
We present theoretical predictions concerning horizontal branch stars in globular clusters, including RR Lyrae variables, as derived from synthetic procedures collating evolutionary and pulsational constraints. On this basis, we explore the predicted behavior of the pulsators as a function of the horizontal branch morphology and over the metallicity range Z=0.0001 to 0.006, revealing an encoura...
متن کاملar X iv : a st ro - p h / 96 11 06 6 v 1 8 N ov 1 99 6 Horizontal Branch Morphology in Galactic Globular Clusters : Dense Environment is “ a ” Second Parameter
The Horizontal Branch (HB) morphology in the color – magnitude diagram of the Galactic globular clusters depends on many factors, and it is now firmly established that the so-called " Second Parameter " is not just the cluster age as claimed for several years. As a part of a wider program devoted to the search for the physical processes driving the Horizontal Branch Morphology, we re-address he...
متن کاملThe Ages of Stars: The Horizontal Branch
Horizontal branch (HB) stars have long played a central role in the age debate. These low-mass stars, which burn helium in the core and hydrogen in a shell, are the immediate progeny of the luminous, vigorously mass-losing red giant branch (RGB) stars. Most importantly in the present context, their temperatures depend strongly on their total masses. More specifically, the lower the mass of an H...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2001