SEARCH FOR BLUE STRAGGLER STARS IN OPEN CLUSTERS FROM GAIA DR2
Blue straggler stars (BSS) are main-sequence stars that appear above the turn-off point of a CMD of multiple star system such as star clusters. Their position in the CMD implied that they prolong their main-sequence life. This makes them a challenge for the standard theory of stellar evolution. Ahu...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/39438 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Blue straggler stars (BSS) are main-sequence stars that appear above the turn-off point of a CMD of multiple star system such as star clusters. Their position in the CMD implied that they prolong their main-sequence life. This makes them a challenge for the standard theory of stellar evolution.
Ahumada & Lapasset (1995, 2007) did a macroscopic study to find out about the existence of BSS in Galactic open clusters (OCs) and made a catalogue of them. However, there are only about 40% OCs that lie in the 1st and 4th Galactic quadrant and even less for the OCs located towards the Galactic center (-60° < l < +60° and -20° < b < +20°). This is expected due to the high level of extinction and crowding hence analyzing OCs located towards this region has always been challenging.
The Gaia survey is an ambitious survey to map the Galaxy in 3D to gain information about the composition, formation, and evolution of Galaxy. This Bachelor Thesis made use of Gaia Data Release 2 or GDR2 (Gaia Collaboration, Brown, et al, 2018) to search for the existence of BSS in some of the OCs located towards the Galactic center and compare them with the data from Ahumada’s & Lapasset’s catalogue (2007). The OCs are chosen from the BSS catalogue in open clusters by Ahumada & Lapasset (2007). The target OCs in this study are NGC 6134, NGC 6404, NGC 6583, and Pismis 18.
The analysis step will be done in three parts; the cluster membership determination using the proper motion data to construct decontaminated CMD, isochrone fitting, and determination of BSS candidates. The determination of BSS candidates consists of two selection; the CMD-based selection (choosing which stars fall on the candidate area) and later the spatial distribution selection. The result is there are 11 candidates in NGC 6134, 4 stars for NGC 6404, 7 stars for NGC 6583, and 3 stars for Pismis 18.
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