Benjamin J. Taylor

The Benchmark Cluster Reddening Project. I. Reddening Values for the Hyades, Coma, and Praesepe

From histories of reddening studies for the Hyades, Praesepe, and nearby field stars, it is concluded that reddening scholarship requires fundamental reform. The adopted protocol for the reformed version of scholarship includes (1) rigorous published foundations for reddening values, (2) explicit quality control of reddening techniques, (3) use of techniques with limited metallicity sensitivity, (4) explicit zero-point control for both input data and derived reddening values, (5) an explicit choice of a reddening zero point, and (6) adherence to statistical norms. It is argued that only limited use should be made of reddening values from (1) spectral types for F0 and later type stars, (2) UBV analysis of blanketed stars, and (3) certain published relations between reddening and distance. However, reddening values may be based safely on (1) polarization measurements, (2) comparisons of β and (R - I)C for F stars, and (3) Stromgren β analysis of A stars. For the Hyades and Coma, upper 95% confidence limits on E(B - V) are found to be ≤1.0 and ≤3.2 mmag, respectively. For Praesepe, the derived value of E(B - V) is 27 ± 4 mmag. The latter result is obtained after an allowance is made for the effects of an anomalous relation between b - y and (R - I)C in Praesepe A stars. A test of the possibility that differential stellar rotation causes the anomaly yields an inconclusive result. Adoption of the revised reddening value instead of the canonical value of zero yields an increase in the derived Praesepe distance modulus by 0.14 mag and a decrease in the derived cluster age by about 11%. In addition, by using published high-dispersion results, it is found that the value of [Fe/H] for Praesepe that is consistent with the derived reddening value is +0.01 ± 0.04 dex. Further results for Praesepe stars will be required for a definitive comparison of the Hyades and Praesepe metallicities.

The Benchmark Cluster Reddening Project. II. A Reddening Value for M67

Since 1954, 70 reddening determinations have been published for M67. Those results are of very diverse quality, and they imply only that the value of E(B - V) for the cluster lies between -0.02 and +0.14 mag. In addition, this uncertainty is habitually concealed by long-standing citation practices. In response, a reformed reddening protocol called alternative scholarship is applied, with tenets including (1) rigorous published foundations for reddening values, (2) accountability for all extant reddening results for M67, (3) explicit quality control of reddening techniques, (4) use of techniques with limited metallicity sensitivity, (5) explicit zero-point control of input data (when possible), (6) a reddening zero point based ultimately on the dust-free solar neighborhood, and (7) adherence to statistical norms. Results from reddening maps are then set aside pending further examination of their zero points and accidental errors. In addition, reddening values derived from color-magnitude analysis and from averages of published reddening results are likewise set aside. Five techniques that satisfy the adopted protocol are then selected and applied. By averaging results from cluster A and F stars and K giants, one finds that the mean value of E(B - V) for M67 is 41 ± 4 mmag. It is also found that extant results from additional techniques are consistent with this result or else can be set aside for plausible reasons. The analysis yields a collateral value of [Fe/H], and this is consistent with the derived reddening value. Using published high-dispersion data, it is found that the mean cluster value of [Fe/H] is -0.009 ± 0.009 dex. For M67 and the Hyades combined, no mean metallicity difference between giants and stars near the main sequence is found that is ≥0.036 dex at 95% confidence.

Statistical Cataloging of Archival Data for Luminosity Class IV-V Stars. III. The Epoch 2004 [Fe/H] and Temperature Catalogs

In this paper, an updated catalog containing averaged values of [Fe/H] is presented for FGK stars on and near the main sequence. The input data for the catalog are values of [Fe/H] derived from weak and moderately strong lines and published before 2005 July 1. Those data are corrected to a uniform temperature scale, and a statistical analysis is then applied to a subset of the data that did not contribute to a previous version of the catalog. In this way, it is found that an accurate zero point for the catalog can be established with an rms error of 0.005 dex. After corrections are applied to a number of the newly added data, it is shown that those corrections help to produce satisfactory zero-point coherence among the catalog entries. Standard errors that are derived for the catalog data are shown to be accurate. It is also shown that those standard errors are based on pervasive scatter in the input data, as is expected if those data are affected by genuine random effects. Samples of the metallicity catalog and an accompanying temperature catalog are displayed and discussed. To make possible an effective extension of the catalog to stars without catalog entries, a database containing photometric metallicities derived by Nordstrom et al. is considered. Standard errors for those metallicities are derived, and zero-point corrections required to put those data on the catalog zero point are presented.

A Catalog of Temperatures and Red Cousins Photometry for the Hyades

Using Hyades photometry published by Mendoza and other authors, Pinsonneault et al. have recently concluded that Cousins V - I photometry published by Taylor & Joner is not on the Cousins system. Extensive tests of the Taylor-Joner photometry and other pertinent results are therefore performed in this paper. It is found that in part, the Pinsonneault et al. conclusion rests on (1) a systematic error in Mendozas (R - I)J photometry and (2) a small error in an approximate Johnson-to-Cousins transformation published by Bessell. For the Taylor-Joner values of (V - R)C, it is found that there are possible (though not definite) differences of several mmag with other results. However, the Taylor-Joner values of (R - I)C data are supported at the 1 mmag level. Using the (R - I)C data and other published results, an (R - I)C catalog is assembled for 146 Hyades stars with spectral types earlier than about K5. For single stars with multiple contributing data, the rms errors of the catalog entries are less than 4.4 mmag. Temperatures on the Di Benedetto angular-diameter scale are also given in the catalog and are used to help update published analyses of high-dispersion values of [Fe/H] for the Hyades. The best current mean Hyades value of [Fe/H] is found to be +0.103 ± 0.008 dex and is essentially unchanged from its previous value. In addition to these numerical results, recommendations are made about improving attitudes and practices that are pertinent to issues like those raised by Pinsonneault et al.

Color changes and absorption-line variations over the inner disk of M31 and the central regions of M32 and NGC 4472

Color changes and absorption line variations in M31, M32 and NGC 4472, attempting synthesis of M31 disk population

ANALYSES OF ARCHIVAL DATA FOR COOL DWARFS. V. AN ANNOTATED CATALOG OF AVERAGED VALUES OF [FE/H]

At the end of this paper is a catalog containing averaged values of [Fe/H] for 398 FGK III-V stars. Original sources for the data are given, and users are urged to cite both these sources and the catalog itself in their own work. The balance of the paper contains comments on [Fe/H] sources of interest. Special note is made of [Fe/H] sources which are not cited in the most recent version of the [Fe/H] catalog (Cayrel de Strobel et al. 1992).

Cousins VRI standard stars in the M 67 dipper asterism

Cousins VRI data for 19 standard stars in the M 67 dipper asterism are presented. With one exception, the values of sigma per mean for these data are lsss than 10 mmag. Because these stars are close together in the sky, they can be used with economy of effort in standardizing CCD images. New Cousins VRI photometry is reported for 23 M 67 stars. For 22 additional cluster stars, new V magnitudes are reported. It is found that some published V data for the Hyades and M 67 must be corrected by small amounts to recover the Landolt (1983) zero point. In addition, faint-star M 67 measurements by Eggen and Sandage (1964) display scatter which is not easily interpreted. The same is true for the (largely) bright-star M 67 data of Johnson and Sandage (1955). The photomultiplier colors of Janes and Smith (1984) and the CCD data of Schild (1983, 1985) are also considered.

ANALYSES OF ARCHIVAL DATA FOR COOL DWARFS. VI. THE 1993 VERSIONS OF THE TEMPERATURE AND [FE/H] CATALOGS

This paper contains supplements to two catalogs which have previously been published by the author. One of the supplements updates a catalog of temperatures for FGK dwarfs (see Taylor 1994b). The other supplement updates a catalog of averaged values of [Fe/H] for the same stars (see Taylor 1994d). The combined catalogs and supplements include values of [Fe/H] published through the end of 1993. Detailed instructions are given for catalog users, including an algorithm for adding data to the [Fe/H] catalog. For recent sources of [Fe/H] which require comment, discussions of issues such as data editing and zero-pint corrections are given. A review is also given of a problem described by Gray (1994), who finds that his spectroscopic temperatures and photometric temperatures from Paper II scatter more around their mean relation than one would expect from the contributing rms errors. It is found that near-Sun reddening (which is Grays preferred solution of the problem) is not a defensible explanation for this scatter. For the moment, the real source of the scatter remains unknown.

ANALYSES OF ARCHIVAL DATA FOR COOL DWARFS. IV. [FE/H] AND RELATED PROPERTIES FOR THE HYADES AND COMA

For Hyades and Coma dwarfs, [Fe/H] is found to be 0.107 ± 0.020 dex, respectively. At the 0.047-dex level, there is no sign of an [Fe/H] offset across the Hyades Li chasm. At the 0.064-dex level, there is no sign of a difference between [Fe/H] for the Hyades dwarfs and giants. At low resolution, the D strong-feature index of Taylor and Johnson (1987) is anomalously weak in the Hyades relative to field stars at 98% confidence or better. This result is from an analysis which excludes log g effects and allows for the effects of binaries. A similar analysis for B-V reveals no definite evidence of an anomaly in this index. In addition, if the Coma dwarfs are compared to their Hyades counterparts and the Coma-Hyades metallicty difference is allowed for, no B-V anomaly emerges.

Radiation-induced apoptosis in MOLT-4 cells requires de novo protein synthesis independent of de novo RNA synthesis

We investigated the effects of inhibition of de novo RNA and protein synthesis in ionizing radiation (IR)‐induced apoptosis in the human T cell line MOLT‐4. We observed that pretreatment with cycloheximide inhibited IR‐induced apoptosis. However, pretreatment with actinomycin D did not inhibit apoptosis induced by IR. These results suggest that apoptosis induced by IR in MOLT‐4 cells requires de novo protein synthesis but not de novo RNA synthesis. This finding suggests that the mRNA encoding the proapoptotic protein(s) is stabilized to facilitate translation independent of de novo gene transcription in response to IR. Our results also indicate that translation of the required proapoptotic protein(s) occurs upstream of mitochondrial depolarization and after 2 h post‐IR.