Ages of Globular Clusters from<i>HIPPARCOS</i>Parallaxes of Local Subdwarfs

Gratton, R.; Pecci, F. Fusi; Carretta, E.; Clementini, G.; Corsi, C. E.; Lattanzi, M. G.

doi:10.1086/304987

Cited by 300 publications

(404 citation statements)

References 68 publications

Supporting

Mentioning

353

Contrasting

Unclassified

Order By: Relevance

“…All of these are roughly 2-3 Gyr younger than previous estimates, due in part to the new longer distance scale suggested by Hipparcos, and also due to improved input physics in the models. 12 ± 1 main sequence fitting (post Hipparcos) [23] 11.8 ± 1.2 main sequence fitting (post Hipparcos) [25] 12 ± 1 Theoretical HB models, main sequence fitting (post H.) [27] 12.2 ± 1.8 Theoretical HB models [28] Where do we go from here? The results of recent years suggest younger ages than previously determined for globular clusters, and also give us more reliable estimates of the uncertainties in the presumed ages, just as David would have liked.…”

Section: Combined Resultsmentioning

confidence: 99%

See 1 more Smart Citation

The age of globular clusters

Krauss

2000

Physics Reports

View full text Add to dashboard Cite

I review here recent developments which have affected our understanding of both the absolute age of globular clusters and the uncertainties in this age estimate, and comment on the implications for cosmological models. This present estimate is in agreement with the range long advocated by David Schramm. The major uncertainty in determining ages of globular clusers based upon the absolute magnitude of the main sequence turn-off remains the uncertainty in the distance to these clusters. Estimates of these distances have recently been upwardly revised due to Hipparcos parallax measurements, if one calibrates luminosities of main sequence stars. However, it is important to realize that at the present time, different distance measures are in disagreement. A recent estimate is that the oldest clusters are 11.5 ± 1.3 Gyr, implying a one-sided 95% confidence level lower limit of 9.5 Gyr, if statistical parallax distance measures are not incorporated. Incorporating more recent measures, including Hipparcos based statistical parallax measures, raises the mean predicted age to 12.8 ± 1 Gyr, with a 95 % confidence range of 10-17 Gyr. I conclude by discussing possible improvements which may allow a more precise age distribution in the near future.

show abstract

Section: Combined Resultsmentioning

confidence: 99%

“…In any case, the excitement over the Hipparcos results has caused a number of groups to determine distances to globular clusters on the basis of main sequence fitting [23][24][25]3]. Care must be taken to isolate those stars with low metallicity, and also to remove possible binary systems from the analysis [3].…”

Section: Main Sequence Fittingmentioning

confidence: 99%

The age of globular clusters

Krauss

2000

Physics Reports

View full text Add to dashboard Cite

show abstract

“…l and b are the Galactic longitude and latitude of the clusters; the symbol μ 0 indicates the true distance modulus of the cluster. References: (1) Gratton et al (1997); (2) Harris (2010); (3) Brasseur et al (2010); (4) Hodder et al (1992); (5) Sarajedini, Dotter, & Kirkpatrick (2009); (6) Hog & Flynn (1998); (7) Anthony-Twarog, Twarog, & Mayer (2007); (8) Sandage, Lubin, & VandenBerg (2003). [M/H] is the estimated error on the metallicity, for each set of derived T eff , log g and [M/H].…”

Section: Introductionmentioning

confidence: 99%

Absolute Magnitude Calibration for Red Giants Based on the Colour–Magnitude Diagrams of Galactic Clusters. III. Calibration with 2MASS

Karaali

Bilir²,

Gökçe³

2013

Publ. Astron. Soc. Aust.

View full text Add to dashboard Cite

We present two absolute magnitude calibrations, M J and M K s , for red giants with the colour-magnitude diagrams of five Galactic clusters with different metallicities, i.e. M92, M13, M71, M67, and NGC 6791. The combination of the absolute magnitudes of the red giant sequences with the corresponding metallicities provides calibration for absolute magnitude estimation for red giants for a given colour

show abstract

“…In perspective, most accurate and robust distances (error < 2%) for a few GCs will be obtained using geometrical methods , an area where also FLAMES plays a crucial role (allowing fast determination of radial velocities for a wide number of stars). However, at present, distances with errors of 3-5% can be obtained for a larger sample of GCs using the Main Sequence Fitting Method (MSFM), exploiting local subdwarfs as standard candles (see Gratton et al 1997;Pont et al 1998;Carretta et al 2000;Gratton et al 2003). Main sources of errors in MSFM are possible systematic differences in reddenings and metallicities between field and GC stars.…”

mentioning

confidence: 99%

Observations of globular clusters with FLAMES

Gratton¹,

Bragaglia

Carretta

et al. 2005

Proc. IAU

Self Cite

View full text Add to dashboard Cite

Abstract. We present preliminary results of a few observing programs conducted with the FLAMES fiber facility at VLT2 ESO telescope. These programs show the large potentiality of FLAMES for investigations of globular clusters. The programs described here concern the derivation of precise reddening and metallicity for globular clusters, and the derivation of abundances for stars on the main sequence of ω Cen. Reddenings with errors of ∆E(B − V ) = 0.005 mag and metallicities with errors of ±0.02 dex (in a scale defined by local subdwarfs) can be obtained in very short observing time. Our results for ω Cen show that the blue main sequence is more metal-rich than the red-main sequence: this requires a large He-content for the blue main sequence.

show abstract

Ages of Globular Clusters fromHIPPARCOSParallaxes of Local Subdwarfs

Cited by 300 publications

References 68 publications

The age of globular clusters

The age of globular clusters

Absolute Magnitude Calibration for Red Giants Based on the Colour–Magnitude Diagrams of Galactic Clusters. III. Calibration with 2MASS

Observations of globular clusters with FLAMES

Contact Info

Product

Resources

About