Chemical inhomogeneity in red giant branch stars and RR Lyrae variables in NGC 1851

Two subpopulations in red giant branch

Jae Woo Lee, Jina Lee, Young Woon Kang, Young-Wook Lee, Sang Il Han, Seok Joo Joo, Soo Chang Rey, David Yong

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

We investigate the red giant branch (RGB) subpopulations of NGC 1851 using Ca uvby photometry. Our colormagnitude diagrams show that the RGB stars have two subpopulations and the RGB stars in NGC 1851 appear to have distinct elemental abundance patterns with the [Ca/H] abundance. We discuss that the elemental abundance patterns can be explained by the contributions from the asymptotic giant stars, confirming the previous studies by others. The RR Lyrae variables in NGC 1851 appear to have a large metallicity spread and, perhaps, a bimodal metallicity distribution. Our period shift analysis of the RR Lyrae variables shows that the helium enhancement appears to be insignificant in the NGC 1851 RR Lyrae population. However, the helium enrichment scenario in the blue or the red parts of horizontal branch (HB) cannot be completely ruled out. Our results show that about 18% of the bright RGB stars have enhanced CNO abundances, sharply in contrast to previous estimates by others (≈38%), making it difficult to explain the double subgiant, RGB sequences, and the bimodal HB distribution by their number ratios.

Original languageEnglish
JournalAstrophysical Journal
Volume695
Issue number1 PART 2
DOIs
Publication statusPublished - 2009 Jan 1

Fingerprint

subpopulation
inhomogeneity
stars
helium
metallicity
giant stars
photometry
diagram
diagrams
chemical
augmentation
shift
estimates
distribution

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Lee, Jae Woo ; Lee, Jina ; Kang, Young Woon ; Lee, Young-Wook ; Han, Sang Il ; Joo, Seok Joo ; Rey, Soo Chang ; Yong, David. / Chemical inhomogeneity in red giant branch stars and RR Lyrae variables in NGC 1851 : Two subpopulations in red giant branch. In: Astrophysical Journal. 2009 ; Vol. 695, No. 1 PART 2.
@article{fef85e9108de464aa20175ca11a9e722,
title = "Chemical inhomogeneity in red giant branch stars and RR Lyrae variables in NGC 1851: Two subpopulations in red giant branch",
abstract = "We investigate the red giant branch (RGB) subpopulations of NGC 1851 using Ca uvby photometry. Our colormagnitude diagrams show that the RGB stars have two subpopulations and the RGB stars in NGC 1851 appear to have distinct elemental abundance patterns with the [Ca/H] abundance. We discuss that the elemental abundance patterns can be explained by the contributions from the asymptotic giant stars, confirming the previous studies by others. The RR Lyrae variables in NGC 1851 appear to have a large metallicity spread and, perhaps, a bimodal metallicity distribution. Our period shift analysis of the RR Lyrae variables shows that the helium enhancement appears to be insignificant in the NGC 1851 RR Lyrae population. However, the helium enrichment scenario in the blue or the red parts of horizontal branch (HB) cannot be completely ruled out. Our results show that about 18{\%} of the bright RGB stars have enhanced CNO abundances, sharply in contrast to previous estimates by others (≈38{\%}), making it difficult to explain the double subgiant, RGB sequences, and the bimodal HB distribution by their number ratios.",
author = "Lee, {Jae Woo} and Jina Lee and Kang, {Young Woon} and Young-Wook Lee and Han, {Sang Il} and Joo, {Seok Joo} and Rey, {Soo Chang} and David Yong",
year = "2009",
month = "1",
day = "1",
doi = "10.1088/0004-637X/695/1/L78",
language = "English",
volume = "695",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1 PART 2",

}

Chemical inhomogeneity in red giant branch stars and RR Lyrae variables in NGC 1851 : Two subpopulations in red giant branch. / Lee, Jae Woo; Lee, Jina; Kang, Young Woon; Lee, Young-Wook; Han, Sang Il; Joo, Seok Joo; Rey, Soo Chang; Yong, David.

In: Astrophysical Journal, Vol. 695, No. 1 PART 2, 01.01.2009.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Chemical inhomogeneity in red giant branch stars and RR Lyrae variables in NGC 1851

T2 - Two subpopulations in red giant branch

AU - Lee, Jae Woo

AU - Lee, Jina

AU - Kang, Young Woon

AU - Lee, Young-Wook

AU - Han, Sang Il

AU - Joo, Seok Joo

AU - Rey, Soo Chang

AU - Yong, David

PY - 2009/1/1

Y1 - 2009/1/1

N2 - We investigate the red giant branch (RGB) subpopulations of NGC 1851 using Ca uvby photometry. Our colormagnitude diagrams show that the RGB stars have two subpopulations and the RGB stars in NGC 1851 appear to have distinct elemental abundance patterns with the [Ca/H] abundance. We discuss that the elemental abundance patterns can be explained by the contributions from the asymptotic giant stars, confirming the previous studies by others. The RR Lyrae variables in NGC 1851 appear to have a large metallicity spread and, perhaps, a bimodal metallicity distribution. Our period shift analysis of the RR Lyrae variables shows that the helium enhancement appears to be insignificant in the NGC 1851 RR Lyrae population. However, the helium enrichment scenario in the blue or the red parts of horizontal branch (HB) cannot be completely ruled out. Our results show that about 18% of the bright RGB stars have enhanced CNO abundances, sharply in contrast to previous estimates by others (≈38%), making it difficult to explain the double subgiant, RGB sequences, and the bimodal HB distribution by their number ratios.

AB - We investigate the red giant branch (RGB) subpopulations of NGC 1851 using Ca uvby photometry. Our colormagnitude diagrams show that the RGB stars have two subpopulations and the RGB stars in NGC 1851 appear to have distinct elemental abundance patterns with the [Ca/H] abundance. We discuss that the elemental abundance patterns can be explained by the contributions from the asymptotic giant stars, confirming the previous studies by others. The RR Lyrae variables in NGC 1851 appear to have a large metallicity spread and, perhaps, a bimodal metallicity distribution. Our period shift analysis of the RR Lyrae variables shows that the helium enhancement appears to be insignificant in the NGC 1851 RR Lyrae population. However, the helium enrichment scenario in the blue or the red parts of horizontal branch (HB) cannot be completely ruled out. Our results show that about 18% of the bright RGB stars have enhanced CNO abundances, sharply in contrast to previous estimates by others (≈38%), making it difficult to explain the double subgiant, RGB sequences, and the bimodal HB distribution by their number ratios.

UR - http://www.scopus.com/inward/record.url?scp=68149129673&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=68149129673&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/695/1/L78

DO - 10.1088/0004-637X/695/1/L78

M3 - Article

VL - 695

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1 PART 2

ER -