A perspectivist review of supermetallicity studies — 1

Taylor, Benjamin J.

doi:10.1016/0083-6656(82)90008-3

Cited by 12 publications

(6 citation statements)

References 170 publications

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“…On the observational side, uncertainties exist in -22estimates of reddening (cf. Taylor 1982;Burstein, Faber & Gonzalez 1986), metallicity (Burstein et al 1986), distance (MMJ), and scatter observed along the MS (cf. §5, above).…”

Section: Isochone Fittingmentioning

confidence: 99%

Deep Wide-Field Spectrophotometry of the Open Cluster M67

Fan

Burstein

Chen

et al. 1996

The Astronomical Journal

219

214

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We present nine color CCD intermediate-band spectrophotometry of a two square degree field centered on the old open cluster M67, from 3890$\rm \AA$ to nearly 1$\mu$. These observations are taken as a part of the BATC (Beijing-Arizona-Taipei-Connecticut) Color Survey of the Sky, for both scientific and calibration reasons. With these data we show that the BATC survey can reach its goal of obtaining spectrophotometry to a zero point accuracy of 0.01 mag, and down to V = 21 with 0.3 mag random error. We fit the color-magnitude diagrams (CMDs) with Worthey's theoretical models. The net result is the excellent fit of the 4.0 Gyr, [Fe/H] = $-0.10$ model to our data, including a good fit to the main sequence (MS) turn-off. Our data are consistent with a toy model with 50\% of the stars in M67 being binaries and a random distribution of binary mass-ratios, although other models with different mass-ratio distributions cannot be ruled out. The spatial distribution and mass function (MF) of stars in M67 show marked effects of dynamical evolution and evaporation of stars from the cluster. Blue stragglers and binary stars are the most condensed within the cluster, with degree of condensation depending on mass.We find M67 to have an elongated shape, oriented at an angle of $15^{\circ}$ relative to the galactic plane. Within its tidal radius, the observed MF of M67 between 1.2 $\rm M_\odot$ and $\rm 0.8 M_\odot$ has a Salpeter slope $\rm \eta = -1.93 \pm 0.66$. For stars of mass below 0.8 $\rm M_\odot$, $\rm \eta \sim 0$. It is plausible that the leveling-off of the MF at lower masses is a result of evaporation of lower mass stars in this mass range at a rate of one every $\sim 10^7$ years. If so, it is plausible that the IMF of M67 has the canonical field value of $\rm \eta = -2.0$.Comment: 74 pages, including 19 ps figures. Accepted for publication in AJ, Aug, 199

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Section: Isochone Fittingmentioning

confidence: 99%

Deep Wide-Field Spectrophotometry of the Open Cluster M67

Fan

Burstein

Chen

et al. 1996

The Astronomical Journal

219

214

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“…The many divergent determinations of reddening and distance moduli in the literature were also discussed in these papers, including the earliest V, BϪV data measured by Johnson & Sandage (1955) for their initial diagram. A summary of work up to 1981 is given by Taylor (1985).…”

Section: M67mentioning

confidence: 99%

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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“…The Spinrad‐Taylor paper prompted ongoing research on possible ‘SMR’ stars and related topics. 13 years later, two fairly sizeable review papers were required to summarize that research (see Taylor 1982a,b). However, there was no agreement about which stars (if any) are SMR.…”

Section: Introductionmentioning

confidence: 99%

A statistical search for supermetallicity in F, G and K stars

Taylor¹

2002

Monthly Notices of the Royal Astronomical Society

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A B S T R A C THigh-dispersion and low-resolution data are combined to search for super-metal-rich (SMR) FGK stars in the solar neighbourhood and Baade's Window. The data are assessed by using statistical analysis, with their rms errors playing a key role. A star is considered to be SMR if its value of ½Fe=H . þ0:2 dex, while 'borderline' SMR status may be assigned if þ0:1 , ½Fe=H # þ0:2 dex. Borderline SMR status is assigned to m Leo and three other giants, but no full-fledged SMR giants are found in either Baade's Window or the solar neighbourhood. By contrast, the existence of SMR class IV -V stars turns out to be well established, with values found for [Fe/H] that are as large as , þ 0.4 dex. It is concluded that this apparent contrast between class IV -V stars and giants should not be interpreted in astrophysical terms at present because of marked shortcomings in the available data base for giants. Recommendations are made about future research that may cure this problem and extend present knowledge about SMR dwarfs.

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A perspectivist review of supermetallicity studies — 1

Cited by 12 publications

References 170 publications

Deep Wide-Field Spectrophotometry of the Open Cluster M67

Deep Wide-Field Spectrophotometry of the Open Cluster M67

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

A statistical search for supermetallicity in F, G and K stars

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