SX phoenecis stars in the extremely metal-poor globular cluster NGC 5053

James M. Nemec, Mario Mateo, Morgan Burke, Edward W Olszewski

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

The results of a major search for photometrically variable blue straggler stars (BSs) in the extremely metal-poor globular cluster NGC 5053 are presented. The survey is based on photometry of over 200 CCD frames (BVI passbands) taken on 18 nights between 1985 and 1994. Five of the 16 BSs monitored for variability are identified as SX Phe stars and their photometric characteristics derived. These five stars are among the shortest-period (49<F<57 min), lowest luminosity (3.0≲MV≲3.3 mag), smallest amplitude (0.08≲AV≲0.25 mag) SX Phe stars presently known. Their colors and locations in both B and V period-luminosity (P-L) diagrams suggest that four of the stars (blue stragglers 11, 13, 14, and 15 in the Nemec & Cohen 1989 catalog) are fundamental-mode pulsators, while the fifth and bluest star, No. 7, appears to be a first-overtone pulsator. One of the stars, No. 11, exhibits cycle-to-cycle light variations that are consistent with multimode pulsations; however, not enough photometric information is available to derive its secondary pulsation period. Masses for the stars, estimated directly from the general equation of stellar pulsation and relative to the RR Lyrae stars, range from 0.53 script M sign (NC7) to 1.8 script M sign (NC13). The SX Phe stars are used to derive improved P-L-[Fe/H] relations for SX Phe stars, from which a revised distance modulus of (m - M)0=16.06 is obtained for NGC 5053.

Original languageEnglish (US)
Pages (from-to)1186-1228
Number of pages43
JournalAstronomical Journal
Volume110
Issue number3
StatePublished - Sep 1995

Fingerprint

globular clusters
stars
blue stars
metal
metals
diagram
luminosity
cycles
variable stars
night
catalogs
photometry
charge coupled devices
diagrams
harmonics
color

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

SX phoenecis stars in the extremely metal-poor globular cluster NGC 5053. / Nemec, James M.; Mateo, Mario; Burke, Morgan; Olszewski, Edward W.

In: Astronomical Journal, Vol. 110, No. 3, 09.1995, p. 1186-1228.

Research output: Contribution to journalArticle

Nemec, JM, Mateo, M, Burke, M & Olszewski, EW 1995, 'SX phoenecis stars in the extremely metal-poor globular cluster NGC 5053', Astronomical Journal, vol. 110, no. 3, pp. 1186-1228.
Nemec, James M. ; Mateo, Mario ; Burke, Morgan ; Olszewski, Edward W. / SX phoenecis stars in the extremely metal-poor globular cluster NGC 5053. In: Astronomical Journal. 1995 ; Vol. 110, No. 3. pp. 1186-1228.
@article{03a8302e78e04b20b2fbf4f6441c17f5,
title = "SX phoenecis stars in the extremely metal-poor globular cluster NGC 5053",
abstract = "The results of a major search for photometrically variable blue straggler stars (BSs) in the extremely metal-poor globular cluster NGC 5053 are presented. The survey is based on photometry of over 200 CCD frames (BVI passbands) taken on 18 nights between 1985 and 1994. Five of the 16 BSs monitored for variability are identified as SX Phe stars and their photometric characteristics derived. These five stars are among the shortest-period (49<F<57 min), lowest luminosity (3.0≲MV≲3.3 mag), smallest amplitude (0.08≲AV≲0.25 mag) SX Phe stars presently known. Their colors and locations in both B and V period-luminosity (P-L) diagrams suggest that four of the stars (blue stragglers 11, 13, 14, and 15 in the Nemec & Cohen 1989 catalog) are fundamental-mode pulsators, while the fifth and bluest star, No. 7, appears to be a first-overtone pulsator. One of the stars, No. 11, exhibits cycle-to-cycle light variations that are consistent with multimode pulsations; however, not enough photometric information is available to derive its secondary pulsation period. Masses for the stars, estimated directly from the general equation of stellar pulsation and relative to the RR Lyrae stars, range from 0.53 script M sign⊙ (NC7) to 1.8 script M sign⊙ (NC13). The SX Phe stars are used to derive improved P-L-[Fe/H] relations for SX Phe stars, from which a revised distance modulus of (m - M)0=16.06 is obtained for NGC 5053.",
author = "Nemec, {James M.} and Mario Mateo and Morgan Burke and Olszewski, {Edward W}",
year = "1995",
month = "9",
language = "English (US)",
volume = "110",
pages = "1186--1228",
journal = "Astronomical Journal",
issn = "0004-6256",
publisher = "IOP Publishing Ltd.",
number = "3",

}

TY - JOUR

T1 - SX phoenecis stars in the extremely metal-poor globular cluster NGC 5053

AU - Nemec, James M.

AU - Mateo, Mario

AU - Burke, Morgan

AU - Olszewski, Edward W

PY - 1995/9

Y1 - 1995/9

N2 - The results of a major search for photometrically variable blue straggler stars (BSs) in the extremely metal-poor globular cluster NGC 5053 are presented. The survey is based on photometry of over 200 CCD frames (BVI passbands) taken on 18 nights between 1985 and 1994. Five of the 16 BSs monitored for variability are identified as SX Phe stars and their photometric characteristics derived. These five stars are among the shortest-period (49<F<57 min), lowest luminosity (3.0≲MV≲3.3 mag), smallest amplitude (0.08≲AV≲0.25 mag) SX Phe stars presently known. Their colors and locations in both B and V period-luminosity (P-L) diagrams suggest that four of the stars (blue stragglers 11, 13, 14, and 15 in the Nemec & Cohen 1989 catalog) are fundamental-mode pulsators, while the fifth and bluest star, No. 7, appears to be a first-overtone pulsator. One of the stars, No. 11, exhibits cycle-to-cycle light variations that are consistent with multimode pulsations; however, not enough photometric information is available to derive its secondary pulsation period. Masses for the stars, estimated directly from the general equation of stellar pulsation and relative to the RR Lyrae stars, range from 0.53 script M sign⊙ (NC7) to 1.8 script M sign⊙ (NC13). The SX Phe stars are used to derive improved P-L-[Fe/H] relations for SX Phe stars, from which a revised distance modulus of (m - M)0=16.06 is obtained for NGC 5053.

AB - The results of a major search for photometrically variable blue straggler stars (BSs) in the extremely metal-poor globular cluster NGC 5053 are presented. The survey is based on photometry of over 200 CCD frames (BVI passbands) taken on 18 nights between 1985 and 1994. Five of the 16 BSs monitored for variability are identified as SX Phe stars and their photometric characteristics derived. These five stars are among the shortest-period (49<F<57 min), lowest luminosity (3.0≲MV≲3.3 mag), smallest amplitude (0.08≲AV≲0.25 mag) SX Phe stars presently known. Their colors and locations in both B and V period-luminosity (P-L) diagrams suggest that four of the stars (blue stragglers 11, 13, 14, and 15 in the Nemec & Cohen 1989 catalog) are fundamental-mode pulsators, while the fifth and bluest star, No. 7, appears to be a first-overtone pulsator. One of the stars, No. 11, exhibits cycle-to-cycle light variations that are consistent with multimode pulsations; however, not enough photometric information is available to derive its secondary pulsation period. Masses for the stars, estimated directly from the general equation of stellar pulsation and relative to the RR Lyrae stars, range from 0.53 script M sign⊙ (NC7) to 1.8 script M sign⊙ (NC13). The SX Phe stars are used to derive improved P-L-[Fe/H] relations for SX Phe stars, from which a revised distance modulus of (m - M)0=16.06 is obtained for NGC 5053.

UR - http://www.scopus.com/inward/record.url?scp=0007280908&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0007280908&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0007280908

VL - 110

SP - 1186

EP - 1228

JO - Astronomical Journal

JF - Astronomical Journal

SN - 0004-6256

IS - 3

ER -