Long-term investigation of an open cluster Berkeley 65

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Main Authors: Chand, Tarak, Sharma, Saurabh, Singh, Koshvendra, Pandey, Jeewan, Verma, Aayushi, Kaur, Harmeen, Mamta, Chakraborty, Manojit, Ojha, Devendra K., Singh, Ajay Kumar
Format: Preprint
Published: 2025
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author Chand, Tarak
Sharma, Saurabh
Singh, Koshvendra
Pandey, Jeewan
Verma, Aayushi
Kaur, Harmeen
Mamta
Chakraborty, Manojit
Ojha, Devendra K.
Singh, Ajay Kumar
author_facet Chand, Tarak
Sharma, Saurabh
Singh, Koshvendra
Pandey, Jeewan
Verma, Aayushi
Kaur, Harmeen
Mamta
Chakraborty, Manojit
Ojha, Devendra K.
Singh, Ajay Kumar
contents We present a decade-long investigation of a poorly studied cluster, Berkeley 65 (Be 65), using deep optical data from the telescopes of ARIES, Nainital Observatory. We estimate its radius ($R_{cluster}$ = 1.6$^{'}$, aspect ratio of $\sim$1.1), distance (2.0 $\pm$ 0.1 kpc) and age ($\sim$160 Myrs). A clear turn-off point at $\sim$1.7 M$_\odot$ in the mass function suggests the escape of low-mass stars, and the lower photometric mass compared to the dynamical mass indicates ongoing disruption due to external forces. Our long-baseline optical photometric data also identifies 64 periodic and 16 non-periodic stars in this region. We have presented the light curves and the classification of those variables. The periodic stars have periods ranging from $\sim$0.05 days to $\sim$3.00 days and amplitude ranges from $\sim$8 mmag to $\sim$700 mmag. The nonperiodic stars show variation from $\sim$30 mmag to $\sim$500 mmag. The periodic stars include main-sequence pulsating variables such as Slow Pulsating B-type, $δ$ Scuti, RR Lyrae, and $γ$ Doradus. We report a detached binary system and rotating variables similar to BY Draconis-type stars exhibiting variable brightness caused by starspots, chromospheric activity, and magnetic field-related phenomena.
format Preprint
id arxiv_https___arxiv_org_abs_2505_24240
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Long-term investigation of an open cluster Berkeley 65
Chand, Tarak
Sharma, Saurabh
Singh, Koshvendra
Pandey, Jeewan
Verma, Aayushi
Kaur, Harmeen
Mamta
Chakraborty, Manojit
Ojha, Devendra K.
Singh, Ajay Kumar
Solar and Stellar Astrophysics
Astrophysics of Galaxies
We present a decade-long investigation of a poorly studied cluster, Berkeley 65 (Be 65), using deep optical data from the telescopes of ARIES, Nainital Observatory. We estimate its radius ($R_{cluster}$ = 1.6$^{'}$, aspect ratio of $\sim$1.1), distance (2.0 $\pm$ 0.1 kpc) and age ($\sim$160 Myrs). A clear turn-off point at $\sim$1.7 M$_\odot$ in the mass function suggests the escape of low-mass stars, and the lower photometric mass compared to the dynamical mass indicates ongoing disruption due to external forces. Our long-baseline optical photometric data also identifies 64 periodic and 16 non-periodic stars in this region. We have presented the light curves and the classification of those variables. The periodic stars have periods ranging from $\sim$0.05 days to $\sim$3.00 days and amplitude ranges from $\sim$8 mmag to $\sim$700 mmag. The nonperiodic stars show variation from $\sim$30 mmag to $\sim$500 mmag. The periodic stars include main-sequence pulsating variables such as Slow Pulsating B-type, $δ$ Scuti, RR Lyrae, and $γ$ Doradus. We report a detached binary system and rotating variables similar to BY Draconis-type stars exhibiting variable brightness caused by starspots, chromospheric activity, and magnetic field-related phenomena.
title Long-term investigation of an open cluster Berkeley 65
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2505.24240