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- ID:
- ivo://CDS.VizieR/J/AJ/150/134
- Title:
- uvbyCaH{beta} photometry of NGC 752
- Short Name:
- J/AJ/150/134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Precision uvbyCaH{beta} photometry of the nearby old open cluster, NGC752, is presented. The mosaic of CCD fields covers an area ~42' on a side with internal precision at the 0.005-0.010mag level for the majority of stars down to V~15. The CCD photometry is tied to the standard system using an extensive set of published photoelectric observations adopted as secondary standards within the cluster. Multicolor indices are used to eliminate as nonmembers a large fraction of the low probability proper-motion members near the faint end of the main sequence, while identifying 24 potential dwarf members between V=15.0 and 16.5, eight of which have been noted before from Vilnius photometry. From 68 highly probable F dwarf members, we derive a reddening estimate of E(b-y)=0.025+/-0.003 (E(B-V)=0.034+/-0.004), where the error includes the internal photometric uncertainty and the systematic error arising from the choice of the standard (b-y,H{beta}) relation. With reddening fixed, [Fe/H] is derived from the F dwarf members using both m_1_ and hk, leading to [Fe/H]=-0.071+/-0.014(sem) and -0.017+/-0.008(sem), respectively. Taking the internal precision and possible systematics in the standard relations into account, [Fe/H] for NGC 752 becomes -0.03+/-0.02. With the reddening and metallicity defined, we use the Victoria-Regina isochrones on the Stromgren system and find an excellent match for (m-M)=8.30+/-0.05 and an age of 1.45+/-0.05Gyr at the appropriate metallicity.
- ID:
- ivo://CDS.VizieR/J/A+AS/145/275
- Title:
- uvby phot. of suspected beta Pic-like stars
- Short Name:
- J/A+AS/145/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out a Stroemgren photometric survey of thirteen southern bright stars, including {beta} Pictoris itself, during three years, d'Astrophysique de Paris, in order to detect possible weak photometric variations. {beta} Pictoris presents a small long-term variation with a change of brightness by -2.1x10^-3^mag per year, over about two years from beginning of 1996, a situation relatively similar to the one about 18 years ago. Among the other stars, only HD 38392 presents weak photometric variations with a period of 21.4 days, probably related to the star rotation period. The negative result concerning photometric variations of all other stars suggests that those stars are actually really stable and strengthens the reality of the variations discovered in the case of {beta} Pictoris and HD 38392.
- ID:
- ivo://CDS.VizieR/J/other/RMxAA/32.143
- Title:
- uvby photometry in Baade's Window
- Short Name:
- J/other/RMxAA/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained uvby data of a sample of 232 stars in Baade's Window. These observations are presented along with the corresponding diagrams. For a description of the uvby photometric system, see e.g. <GCPD/04>
14965. uvby photometry in NGC 7419
- ID:
- ivo://CDS.VizieR/J/A+A/552/A92
- Title:
- uvby photometry in NGC 7419
- Short Name:
- J/A+A/552/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The open cluster NGC 7419 is known to contain five red supergiants and a very high number of Be stars. However, there are conflicting reports about its age and distance that prevent a useful comparison with other clusters. We intend to obtain more accurate parameters for NGC 7419, using techniques different from those of previous authors, so that it may be used as a calibrator for more obscured clusters. We obtained Stroemgren photometry of the open cluster NGC 7419, as well as classification spectroscopy of ~20 stars in the area. We then applied standard analysis and classification techniques.
- ID:
- ivo://CDS.VizieR/J/A+A/390/1023
- Title:
- uvby photometry of 4 CP stars
- Short Name:
- J/A+A/390/1023
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential Stroemgren uvby observations from the Four College Automated Photoelectric Telescope (FCAPT) are presented for the CP stars HR 149 and HR 7911 and the mCP stars HD 32966 and HD 171782. The Hg-Mn star HR 149 is found to be constant while HR 7911 with a period of 5.9617 days probably has a component which is a magnetic CP star. Improved periods were derived for HD 32966 and HD 171782 of 3.0927 and 4.4674 days, respectively. The former is a rather large amplitude mCP star. Both have at least one light curve different in shape from the others observed.
- ID:
- ivo://CDS.VizieR/J/A+A/487/1081
- Title:
- uvby photometry of 6 eclipsing binaries
- Short Name:
- J/A+A/487/1081
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate mass, radius, and abundance determinations from binaries provide important information on stellar evolution, fundamental to central fields in modern astrophysics and cosmology. Within the long-term Copenhagen Binary Project, we aim to obtain high-quality light curves and standard photometry for double-lined detached eclipsing binaries with late A, F, and G type main-sequence components, needed for the determination of accurate absolute dimensions and abundances, and for detailed comparisons with results from recent stellar evolutionary models. Between March 1985 and July 2007, we carried out photometric observations of AD Boo, HW CMa, SW CMa, V636 Cen, VZ Hya, and WZ Oph at the Stromgren Automatic Telescope at ESO, La Silla. We obtained complete uvby light curves, ephemerides, and standard uvby{beta} indices for all six systems.
- ID:
- ivo://CDS.VizieR/J/A+A/402/509
- Title:
- uvby photometry of four MC eclipsing binaries
- Short Name:
- J/A+A/402/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new accurate CCD uvby light curves for the LMC eclipsing binaries HV 982 and HV 12578, and for the SMC systems HV 1433 and HV 11284 obtained at the Danish 1.5m telescope at ESO, La Silla, equipped with a direct camera and CCD #28 (a thinned 1024x1024 Tek device), during several periods between November 1992 and November 1995. The light curves were derived from DoPHOT photometry, and typical accuracies are between 0.007 and 0.012mag per point. Standard uvby indices have also been established for each binary, primarily for determination of interstellar reddening and absorption. For HV 982 and HV 12578, accurate photometric elements have been established. Both systems consist of two detached components of comparable sizes in an eccentric orbit.
- ID:
- ivo://CDS.VizieR/J/ApJ/754/83
- Title:
- UV continuum for z~4-7 star-forming galaxies
- Short Name:
- J/ApJ/754/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ultra-deep Advanced Camera for Surveys (ACS) and WFC3/IR HUDF+HUDF09 data, along with the wide-area GOODS+ERS+CANDELS data over the CDF-S GOODS field, are used to measure UV colors, expressed as the UV-continuum slope {beta}, of star-forming galaxies over a wide range of luminosity (0.1L*_z=3_ to 2L*_z=3_) at high redshift (z~7 to z~4). {beta} is measured using all ACS and WFC3/IR passbands uncontaminated by Ly{alpha} and spectral breaks. Extensive tests show that our {beta} measurements are only subject to minimal biases. Using a different selection procedure, Dunlop et al. (2012MNRAS.420..901D) recently found large biases in their {beta} measurements. To reconcile these different results, we simulated both approaches and found that {beta} measurements for faint sources are subject to large biases if the same passbands are used both to select the sources and to measure {beta}. High-redshift galaxies show a well-defined rest-frame UV color-magnitude (CM) relationship that becomes systematically bluer toward fainter UV luminosities. No evolution is seen in the slope of the UV CM relationship in the first 1.5 Gyr, though there is a small evolution in the zero point to redder colors from z~7 to z~4. This suggests that galaxies are evolving along a well-defined sequence in the L_UV_-color ({beta}) plane (a "star-forming sequence"?). Dust appears to be the principal factor driving changes in the UV color {beta} with luminosity. These new larger {beta} samples lead to improved dust extinction estimates at z~4-7 and confirm that the extinction is essentially zero at low luminosities and high redshifts. Inclusion of the new dust extinction results leads to (1) excellent agreement between the star formation rate (SFR) density at z~4-8 and that inferred from the stellar mass density; and (2) to higher specific star formation rates (SSFRs) at z>~4, suggesting that the SSFR may evolve modestly (by factors of ~2) from z~4-7 to z~2.
- ID:
- ivo://CDS.VizieR/J/ApJ/793/115
- Title:
- UV-continuum slopes beta for z~4-8 galaxies
- Short Name:
- J/ApJ/793/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the UV-continuum slope {beta} for over 4000 high-redshift galaxies over a wide range of redshifts z~4-8 and luminosities from the HST HUDF/XDF, HUDF09-1, HUDF09-2, ERS, CANDELS-N, and CANDELS-S data sets. Our new {beta} results reach very faint levels at z~4 (-15.5 mag: 0.006 L_z=3_^*^), z~5 (-16.5 mag: 0.014 L_z=3_^*^), and z~6 and z~7 (-17 mag: 0.025 L_z=3_^*^). Inconsistencies between previous studies led us to conduct a comprehensive review of systematic errors and develop a new technique for measuring {beta} that is robust against biases that arise from the impact of noise. We demonstrate, by object-by-object comparisons, that all previous studies, including our own and those done on the latest HUDF12 data set, suffered from small systematic errors in {beta}. We find that after correcting for the systematic errors (typically {Delta}{beta}~0.1-0.2) all {beta} results at z~7 from different groups are in excellent agreement. The mean {beta} we measure for faint (-18 mag: 0.1L_z=3_^*^) z~4, z~5, z~6, and z~7 galaxies is -2.03+/-0.03+/-0.06 (random and systematic errors), -2.14+/-0.06+/-0.06, -2.24+/-0.11+/-0.08, and -2.30+/-0.18+/-0.13, respectively. Our new {beta} values are redder than we have reported in the past, but bluer than other recent results. Our previously reported trend of bluer {beta}'s at lower luminosities is confirmed, as is the evolution to bluer {beta}'s at high redshifts. {beta} appears to show only a mild luminosity dependence faintward of M_UV, AB_~-19 mag, suggesting that the mean {beta} asymptotes to ~-2.2 to -2.4 for faint z>=4 galaxies. At z~7, the observed {beta}'s suggest non-zero, but low dust extinction, and they agree well with values predicted in cosmological hydrodynamical simulations.
