Open Cluster LW 55 in the Large Magellanic Cloud

Kałużny, J.; Ruciński, S. M.

doi:10.1086/375548

Cited by 86 publications

(184 citation statements)

References 22 publications

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“…Figure 8 and Table 3. They are almost identical to the CMD tabulated by S62a, and they agree well with those of Kaluzny & Rucinski (1995) 4 In order for the models to provide a satisfactory match to the morphology of the NGC 188 CMD (in particular to the shape and length of the subgiant branch), it is necessary to assume E(BϪV (if the solar metallicity is also as-) p 0.095 sumed). In so doing, a fully consistent interpretation of both M67 and NGC 188 is obtained, as seen in Figure 8, where the theoretical isochrones agree quite well with the observational fiducial points.…”

Section: Ngc 188supporting

confidence: 69%

The Age of the Oldest Stars in the Local Galactic Disk fromHipparcosParallaxes of G and K Subgiants

Sandage

Lubin

VandenBerg

2003

PUBL ASTRON SOC PAC

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ABSTRACT. We review the history of the discovery of field subgiant stars, the role that they played in the development of the early understanding of stellar evolution, and their importance in the age dating of the Galactic disk. We use the cataloged data from the Hipparcos satellite in this latter capacity.Based on Hipparcos parallaxes with relative accuracies of , the absolute magnitude of the lower , as well as to the envelope of the reddest main-sequence stars at . The rededge of the densest part of the distribution of field giants is, however, most readily matched by isochrones having [Fe/H . Such high metal abundances are evidently confirmed by the spectroscopically observed high ] ≈ ϩ0.23 metallicity (between [Fe/H and ϩ0.4) of the old thick-disk Galactic cluster NGC 6791, whose color-] p ϩ0.2 magnitude diagram can be made to fit either of these red boundaries by adopting suitable values for the reddening and distance modulus (from within the observed ranges of uncertainties of these quantities).The age of the field stars in the solar neighborhood is found to be Gyr (or Gyr if the stellar 7.9 ‫ע‬ 0.7 7.4 ‫ע‬ 0.7 models allow for the effects of diffusive processes) by fitting the theoretical isochrones for [Fe/H to the ] p ϩ0.37 lower envelope of the Hipparcos subgiants. However, this age is a function of metallicity. The models show a dependence of at for metallicities between 0.00 and ϩ0.37. The same grid dt p Ϫ3.99([Fe/H] Ϫ 0.37) M ∼ ϩ4 V of isochrones yields ages, in turn, of , , and 7.5 to 10 Gyr (depending on the assumed reddening) 4.0 ‫ע‬ 0.2 6.2 ‫ע‬ 0.5 for the old Galactic clusters M67, NGC 188, and NGC 6791 using metal abundances, distance moduli, and reddenings adopted in the text. Although the distance (and hence age) of NGC 6791 is somewhat uncertain, the ages of both the Galactic disk in the solar neighborhood and of NGC 6791 are, nevertheless, likely between 3 and 5 Gyr younger than the oldest halo globular clusters, which have ages of ∼13.5 Gyr. The conclusion is the same as that reached earlier by Liu & Chaboyer, who used Hipparcos parallax stars that were mainly near the main-sequence turnoff rather than at the lower bound of the subgiant luminosity that we determine here. The most significant results are (1) the supermetallicity of the oldest local disk stars and (2) the large age difference between the most metal poor component of the halo and the thick and thin disk in the solar neighborhood, confirming Liu & Chaboyer. These facts are undoubtedly related and pose again the problem of the proper scenario for the timing of events in the formation of the halo and the Galactic disk in the solar neighborhood.1 Part review of the history of the discovery of subgiants and part new results from Hipparcos.

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Section: Ngc 188supporting

confidence: 69%

The Age of the Oldest Stars in the Local Galactic Disk fromHipparcosParallaxes of G and K Subgiants

Sandage

Lubin

VandenBerg

2003

PUBL ASTRON SOC PAC

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“…This cluster has been studied extensively for variability by the PISCES project (Mochejska et al 2002(Mochejska et al , 2005; additional variability surveys of this cluster include those by Kaluzny & Ruciński 1993, Ruciński et al 1996, Mochejska et al 2003, and Bruntt et al 2003. As noted in Mochejska et al (2005), the cluster is populous (Kaluzny & Udalski 1992), old ( ¼ 8 Gyr), metal-rich (½Fe/H ¼ þ0:4), and located at a distance modulus of (m À M ) V ¼ 13:42 (Chaboyer et al 1999).…”

Section: Observationsmentioning

confidence: 99%

Pushing the Limits of Ground-based Photometric Precision: Submillimagnitude Time-Series Photometry of the Open Cluster NGC 6791

et al. 2005

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We present the results from a three-night, time-series study of the open cluster NGC 6791 using the Megacam wide-field mosaic CCD camera on the 6.5 m MMT telescope. The aim of this study was to demonstrate the ability to obtain very high precision photometry for a large number of stars. We achieved better than 1% precision for more than 8000 stars with 14:3 < R < 20:1 and submillimagnitude (as low as 0.36 mmag) precision for over 300 stars with 14:6 < R < 16:3 in the field of this cluster. We also discovered 10 new variable stars, including a possible Scuti variable with an amplitude of 2%, eight likely W UMa contact binaries, and a possible RS CVn star, and we identified seven suspected low-amplitude variables, including one star with an amplitude of 4 mmag. We comment on the implications of this study for a ground-based survey for transiting planets as small as Neptune.

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“…Using Kepler photometry, Corsaro et al (2012) studied solar-like oscillations of red giants of the cluster. Photometric studies of some of the variable stars in NGC 6791 have also been made by Brogaard et al (2011), Kaluzny & Rucinski (1993) and de Marchi et al (2007).…”

Section: Introductionmentioning

confidence: 99%

“…Kaluzny & Rucinski (1993) and Rucinski, Kaluzny, & Hilditch (1996) determined its orbital period. Later Grundahl et al (2008) and Brogaard et al (2011) performed light and radial velocity analyses of ground-based data and determined masses of 1.0868 ± 0.0039M⊙ and 0.8276 ± 0.0022M⊙, radii of 1.397 ± 0.013R⊙ and 0.7813 ± 0.0053R⊙ for the primary and secondary components.…”

Section: Introductionmentioning

confidence: 99%

A turn-off detached binary star V568 Lyr in theKeplerfield of the oldest open cluster (NGC 6791) in the Galaxy

Yakut

Eggleton

Kalomeni

et al. 2015

Mon. Not. R. Astron. Soc.

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We present the Kepler photometric light-variation analysis of the late-type doublelined binary system V568 Lyr that is in the field of the high metallicity old open cluster NGC 6791. The radial velocity and the high-quality short-cadence light curve of the system are analysed simultaneously. The masses, radii and luminosities of the component stars are.018 L⊙ and their separation is a = 31.060 ± 0.002 R⊙. The distance to NGC 6791 is determined to be 4.260 ± 0.290 kpc by analysis of this binary system. We fit the components of this well-detached binary system with evolution models made with the Cambridge stars and ev(twin) codes to test low-mass binary star evolution. We find a good fit with a metallicity of Z = 0.04 and an age of 7.704 Gyr. The standard tidal dissipation, included in ev(twin) is insufficient to arrive at the observed circular orbit unless it formed rather circular to begin with.

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Open Cluster LW 55 in the Large Magellanic Cloud

Cited by 86 publications

References 22 publications

The Age of the Oldest Stars in the Local Galactic Disk fromHipparcosParallaxes of G and K Subgiants

The Age of the Oldest Stars in the Local Galactic Disk fromHipparcosParallaxes of G and K Subgiants

Pushing the Limits of Ground-based Photometric Precision: Submillimagnitude Time-Series Photometry of the Open Cluster NGC 6791

A turn-off detached binary star V568 Lyr in theKeplerfield of the oldest open cluster (NGC 6791) in the Galaxy

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