The Not so Simple Stellar System ω Cen. II. Evidence in Support of a Merging Scenario
(2020) In Astrophysical Journal 891(2).- Abstract
We present multiband photometry covering ∼5° × 5° across ω Cen collected with the Dark Energy Camera on the 4 m Blanco telescope, combined with Hubble Space Telescope and Wide Field Imager data for the central regions. The unprecedented photometric accuracy and field coverage allows us to confirm the different spatial distribution of blue and red main-sequence stars, and of red giant branch (RGB) stars with different metallicities. The ratio of the number of blue to red main-sequence stars shows that the blue main-sequence stellar subpopulation has a more extended spatial distribution compared to the red main-sequence one, with the frequency of blue main-sequence stars increasing at a distance of ∼20′ from ω Cen's center. Similarly, the... (More)
We present multiband photometry covering ∼5° × 5° across ω Cen collected with the Dark Energy Camera on the 4 m Blanco telescope, combined with Hubble Space Telescope and Wide Field Imager data for the central regions. The unprecedented photometric accuracy and field coverage allows us to confirm the different spatial distribution of blue and red main-sequence stars, and of red giant branch (RGB) stars with different metallicities. The ratio of the number of blue to red main-sequence stars shows that the blue main-sequence stellar subpopulation has a more extended spatial distribution compared to the red main-sequence one, with the frequency of blue main-sequence stars increasing at a distance of ∼20′ from ω Cen's center. Similarly, the more metal-rich RGB stars show a more extended spatial distribution compared to the more metal-poor ones in the outskirts of the cluster. Moreover, the centers of the distributions of metal-rich and metal-poor RGB stars are shifted in different directions with respect to the geometrical center of ω Cen. We constructed stellar density profiles for the blue and red main-sequence stars; they show that the blue main-sequence stellar subpopulation has a more extended spatial distribution compared to the red main-sequence one in the outskirts of ω Cen, confirming the results based on the number ratio. We also computed the ellipticity profile of ω Cen, which has a maximum value of 0.16 at a distance of ∼8′ from the center, and a minimum of 0.05 at ∼30′; the average ellipticity is ∼0.10. The circumstantial evidence presented in this work suggests a merging scenario for the formation of the peculiar stellar system ω Cen.
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- author
- Calamida, Annalisa ; Zocchi, Alice ; Bono, Giuseppe ; Ferraro, Ivan ; Mastrobuono-Battisti, Alessandra LU ; Saha, Abhijit ; Iannicola, Giacinto ; Rest, Armin ; Strampelli, Giovanni and Zenteno, Alfredo
- organization
- publishing date
- 2020-03-17
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Astrophysical Journal
- volume
- 891
- issue
- 2
- article number
- 167
- publisher
- American Astronomical Society
- external identifiers
-
- scopus:85084067260
- ISSN
- 0004-637X
- DOI
- 10.3847/1538-4357/ab77c0
- language
- English
- LU publication?
- yes
- id
- cdd058d6-f88f-452b-b9d1-e4a84bc1f680
- date added to LUP
- 2020-05-13 16:57:44
- date last changed
- 2022-12-16 03:58:18
@article{cdd058d6-f88f-452b-b9d1-e4a84bc1f680,
abstract = {{<p>We present multiband photometry covering ∼5° × 5° across ω Cen collected with the Dark Energy Camera on the 4 m Blanco telescope, combined with Hubble Space Telescope and Wide Field Imager data for the central regions. The unprecedented photometric accuracy and field coverage allows us to confirm the different spatial distribution of blue and red main-sequence stars, and of red giant branch (RGB) stars with different metallicities. The ratio of the number of blue to red main-sequence stars shows that the blue main-sequence stellar subpopulation has a more extended spatial distribution compared to the red main-sequence one, with the frequency of blue main-sequence stars increasing at a distance of ∼20′ from ω Cen's center. Similarly, the more metal-rich RGB stars show a more extended spatial distribution compared to the more metal-poor ones in the outskirts of the cluster. Moreover, the centers of the distributions of metal-rich and metal-poor RGB stars are shifted in different directions with respect to the geometrical center of ω Cen. We constructed stellar density profiles for the blue and red main-sequence stars; they show that the blue main-sequence stellar subpopulation has a more extended spatial distribution compared to the red main-sequence one in the outskirts of ω Cen, confirming the results based on the number ratio. We also computed the ellipticity profile of ω Cen, which has a maximum value of 0.16 at a distance of ∼8′ from the center, and a minimum of 0.05 at ∼30′; the average ellipticity is ∼0.10. The circumstantial evidence presented in this work suggests a merging scenario for the formation of the peculiar stellar system ω Cen.</p>}},
author = {{Calamida, Annalisa and Zocchi, Alice and Bono, Giuseppe and Ferraro, Ivan and Mastrobuono-Battisti, Alessandra and Saha, Abhijit and Iannicola, Giacinto and Rest, Armin and Strampelli, Giovanni and Zenteno, Alfredo}},
issn = {{0004-637X}},
language = {{eng}},
month = {{03}},
number = {{2}},
publisher = {{American Astronomical Society}},
series = {{Astrophysical Journal}},
title = {{The Not so Simple Stellar System ω Cen. II. Evidence in Support of a Merging Scenario}},
url = {{http://dx.doi.org/10.3847/1538-4357/ab77c0}},
doi = {{10.3847/1538-4357/ab77c0}},
volume = {{891}},
year = {{2020}},
}