Homogeneous Photometry for Star Clusters and Resolved Galaxies. II. Photometric Standard Stars

Stetson, P. B.

doi:10.1086/316595

Cited by 591 publications

(705 citation statements)

References 12 publications

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“…Although gravitational settling and radiative levitation are clearly detected in hot horizontal branch stars in globular clusters (Behr, Cohen, & McCarthy 1999, 2000, we continue to see no evidence for such effects in our sample of red giant branch, subgiants, and main-sequence globular cluster stars, either in Fe i or in any of the abundance ratios discussed below. To within the precision of our measurements, there is no evidence for any change in abundances with decreasing T eff , i.e., with decreasing luminosity, between the tip of the RGB and the main-sequence turnoff.…”

Section: No 1 2003mentioning

confidence: 44%

“…This cluster lies considerably farther from the galactic plane at b = À23 than does M71, hence field-star contamination is a much less serious problem for M5. The photometric database of Stetson, Hesser, & Smecker-Hane (1998) and Stetson (2000), which is described in considerable detail in Cohen et al (2002), was used to verify that the selected stars lie on the cluster locus in various color-magnitude diagrams. For the more luminous stars, we required the assignment of a high probability of membership by Cudworth (1979) in his proper-motion survey of this globular cluster.…”

Section: Stellar Samplementioning

confidence: 99%

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Abundances in Stars from the Red Giant Branch Tip to near the Main-Sequence Turnoff in M5

Ramírez

Cohen

2003

The Astronomical Journal

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We present the iron abundance and abundance ratios for 18 elements with respect to Fe in a sample of stars with a wide range in luminosity, from luminous giants to stars near the turnoff in the globular cluster M5. The analyzed spectra, obtained with the High Resolution Echelle Spectrograph at the Keck Observatory, are of high dispersion (R = /D = 35,000). We find that the neutron capture, the iron peak, and the -element abundance ratios show no trend with T eff and low scatter around the mean between the top of the red giant branch and near the main-sequence turnoff, suggesting that at this metallicity non-LTE effects are not important over the range of stellar parameters spanned by our sample. To within the precision of the measurements (about AE0.1 dex), gravitationally induced heavy-element diffusion does not appear to be present among the stars near the main-sequence turnoff studied here. Our work and other recent studies suggest that heavy-element diffusion is inhibited in the surface layers of metal-poor stars. Differences in the Na abundance from star to star that extend to the main-sequence turnoff are detected in our sample in M5. The anticorrelation between O and Na abundances, observed in other metal-poor globular clusters, is not detected in our sample, but it may be hidden among stars with only upper limits for their O abundances. As we found in M71, there is a hint of star-to-star variation in the Zr abundance. Overall the abundance ratios of M5 appear very similar to those of M71, with the possible exception of the neutron capture element Ba, for which we argue that the apparent difference may be due to difficulties in the analysis. As in M71, the -elements Mg, Ca, Si, and Ti are overabundant relative to Fe. The results of our abundance analysis of 25 stars in M5 provide further evidence of abundance variations among specific light elements at unexpectedly low luminosities, which cannot be explained by our current understanding of stellar evolution.

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Section: No 1 2003mentioning

confidence: 44%

Section: Stellar Samplementioning

confidence: 99%

Abundances in Stars from the Red Giant Branch Tip to near the Main-Sequence Turnoff in M5

Ramírez

Cohen

2003

The Astronomical Journal

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“…Two of these, CL0159+0030 and CL0809+2811, are situated within the SDSS DR6 footprint. In addition, we observed and used Stetson (2000) standard fields overlapping with SDSS.…”

Section: Calibration Pipelinementioning

confidence: 99%

The400dGalaxy Cluster Survey weak lensing programme

Israel¹,

Erben²,

Reiprich³

et al. 2010

A&A

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Context. Studying cosmological structure formation provides insights into all of the universe's components: baryonic matter, dark matter, and, notably, dark energy. Measuring the mass function of galaxy clusters at high redshifts is particularly useful probe for both learning about the history of structure formation and constraining cosmological parameters. Aims. We attempt to derive reliable masses for a high-redshift, high-luminosity sample of galaxy clusters selected from the 400d X-ray selected cluster survey. Weak gravitational lensing allows us to determine masses that can be compared with those inferred from X-rays, forming an independent test. We focus on a particular object, CL0030+2618 at z = 0.50. Methods. Using deep imaging in three passbands acquired using the Megacam instrument at MMT, we show that Megacam is well-suited to measuring gravitational shear, i.e., the shapes of faint galaxies. A catalogue of background galaxies is constructed by analysing the photometric properties of galaxies in the g r i bands. Results. Using the aperture mass technique, we detect the weak lensing signal of CL0030+2618 at 5.8σ significance. We find significant tangential alignment of galaxies out to ∼10 or a distance of >2 r 200 from the cluster centre. The weak lensing centre of CL0030+2618 agrees with several X-ray measurements and the position of the brightest cluster galaxy. Finally, we infer a weak lensing virial mass of M 200 = 7.2 +3.6+2.3 −2.9−2.5 × 10 14 M for CL0030+2618. Conclusions. Despite complications caused by a tentative foreground galaxy group along the line of sight, the X-ray and weak lensing estimates for CL0030+2618 are in remarkable agreement.

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“…In order to determine upper limits on the brightness of the pulsar companions, we performed PSF photometry on the averaged deep images using DAOPHOT II (Stetson 1987). The resulting instrumental magnitudes were calibrated against 47 standard stars in the PG 1525−071 using the calibrated magnitudes of Stetson (2000). Since only R-band observations were taken, only the zeropoint was fitted for the calibration, giving rms residuals of 0.02 mag.…”

Section: Optical Observationsmentioning

confidence: 99%

Long-term timing of four millisecond pulsars

Janssen

Stappers

Bassa

et al. 2010

A&A

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We have timed four millisecond pulses, PSRs J1721−2457, J1745−0952, J1810−2005, and J1918−0642, for up to a total of 10.5 years each using multiple telescopes in the European Pulsar Timing Array network: the Westerbork Synthesis Radio Telescope in The Netherlands, the Nançay Radio Telescope in France and the Lovell telescope at Jodrell Bank in the UK. The long time span has enabled us to measure the proper motions of J1745−0952 and J1918−0642, indicating that they have transverse velocities of 200 (50) and 54(7) km s −1 respectively. We have obtained upper limits on the proper motion of J1721−2457 and J1810−2005, which imply that they have transverse velocities less than 140 and 400 km s −1 respectively. In all cases, the velocities lie in the range typical of millisecond pulsars. We present pulse profiles for each pulsar taken from observations at multiple frequencies in the range of 350 to 2600 MHz, and show that J1810−2005 shows significant profile evolution in this range. Using our multi-frequency observations, we measured the spectral indices for all four pulsars, and for J1810−2005 it appears to be very flat. The flux density of J1918−0642 shows extensive modulation which we attribute to the combined effects of refractive and diffractive scintillation. We discuss the possible use of including J1721−2457 or J1918−0642 in a pulsar timing array, and find that J1918−0642 will be useful to include when the timing precision of this pulsar is improved over the next few years. We have searched archival optical observations to detect companions of the binary pulsars, but none were detected. However, we provide lower limits on the masses of the white dwarf companions of PSRs J1745−0952 and J1918−0642.

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Homogeneous Photometry for Star Clusters and Resolved Galaxies. II. Photometric Standard Stars

Cited by 591 publications

References 12 publications

Abundances in Stars from the Red Giant Branch Tip to near the Main-Sequence Turnoff in M5

Abundances in Stars from the Red Giant Branch Tip to near the Main-Sequence Turnoff in M5

The400dGalaxy Cluster Survey weak lensing programme

Long-term timing of four millisecond pulsars

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