Is the young star association ε Cha double?

The kinematics of the ε Cha young stellar association close to the Sun has been studied based on a list of candidate stars from the Dickson-Vandervelde work. The working sample consists of 26 stars with parallaxes, proper motions from the Gaia DR3 catalog and radial velocities taken from literary sources. The orbits of the stars back to the past were constructed, and the moment when the association had a minimum spatial size was determined, as well as an analysis of the dependencies of the velocities U, V, W on the coordinates x, y, z was carried out. It is shown that the initial sample is divided into two parts with different kinematic properties. The first sample included 9 stars. Based on the construction of the orbits of these 9 stars, an age estimate of t = 4.9 ± 0.8 million years was obtained. An expansion coefficient in the xz plane with the value Kxz = 135±19 km/s/kpc was also found for them, on the basis of which another age estimate t = 7.2 ± 1.0 million years was obtained. The second sample included 17 stars. The construction of their orbits gave an estimate of age t = 0.2 ± 0.3 million years, and based on the gradient dW/dz = 707 ± 248 km/s/kpc, a second estimate of their age t = 1.4 ± 0.5 million years was obtained. This suggests that the ε Cha association either consists of two groupings of different ages, or a younger one arose as a result of a recent outbreak of star formation within a common star system. The question of the gravitational connection of the groupings has not been considered in the framework of this work.

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Journal
Астрономический журнал
Published
2024-09-27
DOI
https://doi.org/10.31857/s0004629924030039
Primary Topic
Stellar, planetary, and galactic studies
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article
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article

Is the young star association ε Cha double?

В. В. Бобылев, A. T. Bajkova
Астрономический журнал
Stellar, planetary, and galactic studies
article

Is the young star association ε Cha double?

В. В. Бобылев, A. T. Bajkova
article en

Abstract

The kinematics of the ε Cha young stellar association close to the Sun has been studied based on a list of candidate stars from the Dickson-Vandervelde work. The working sample consists of 26 stars with parallaxes, proper motions from the Gaia DR3 catalog and radial velocities taken from literary sources. The orbits of the stars back to the past were constructed, and the moment when the association had a minimum spatial size was determined, as well as an analysis of the dependencies of the velocities U, V, W on the coordinates x, y, z was carried out. It is shown that the initial sample is divided into two parts with different kinematic properties. The first sample included 9 stars. Based on the construction of the orbits of these 9 stars, an age estimate of t = 4.9 ± 0.8 million years was obtained. An expansion coefficient in the xz plane with the value Kxz = 135±19 km/s/kpc was also found for them, on the basis of which another age estimate t = 7.2 ± 1.0 million years was obtained. The second sample included 17 stars. The construction of their orbits gave an estimate of age t = 0.2 ± 0.3 million years, and based on the gradient dW/dz = 707 ± 248 km/s/kpc, a second estimate of their age t = 1.4 ± 0.5 million years was obtained. This suggests that the ε Cha association either consists of two groupings of different ages, or a younger one arose as a result of a recent outbreak of star formation within a common star system. The question of the gravitational connection of the groupings has not been considered in the framework of this work.

Астрономический журналVol. 101(3)
Russian Academy of Sciences (RU)
Openalex Percentile: Top 88%
Stellar, planetary, and galactic studies
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Is the young star association ε Cha double? — В. В. Бобылев, A. T. Bajkova · Астрономический журнал (2024) | TGRS Research Map | TGRS