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4611. VRI photometric standards for NGC 6946
ID:
ivo://CDS.VizieR/J/ApJ/669/525
Title:
VRI photometric standards for NGC 6946
Short Name:
J/ApJ/669/525
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new, very late time optical photometry and spectroscopy of the interesting Type II-P supernova SN 2002hh, in NGC 6946. Gemini/GMOS-N has been used to acquire visible spectra at six epochs between 2004 August and 2006 July, following the evolution of the SN from age 661 to 1358-days. Few optical spectra of Type II supernovae with ages greater than 1yr exist. In addition, g', r', and i' images were acquired at all six epochs. The spectral and photometric evolution of SN 2002hh has been very unusual. Measures of the brightness of this SN, both in the R and I bands, as well as in the Halpha emission flux, show no significant fading over an interval of nearly 2-years.
4612. VRI photometry and theta values in open clusters
ID:
ivo://CDS.VizieR/J/ApJS/176/262
Title:
VRI photometry and theta values in open clusters
Short Name:
J/ApJS/176/262
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, new Cousins VRI data are presented for NGC 752 and Praesepe, and new and extant data are combined into an augmented database for M67. For those three clusters, catalogs containing Cousins VRI photometry, reddening-corrected values of (V-K)J, and temperatures are produced. The same is done for Coma by using both previously published and newly derived Cousins photometry. An extant set of catalogs for the Hyades is updated to include V magnitudes and values of (R-I)C that were published after the original catalogs appeared. Finally, M67 V magnitudes published previously by Sandquist are corrected for an effect that depends on location on the face of the cluster. The corrected data and values of (V-I)C given by Sandquist are then set out in a supplementary catalog.
4613. VRI photometry in NGC 7129
ID:
ivo://CDS.VizieR/J/AJ/149/200
Title:
VRI photometry in NGC 7129
Short Name:
J/AJ/149/200
Date:
21 Oct 2021
Publisher:
CDS
Description:
NGC7129 is a bright reflection nebula located in the molecular cloud complex near l=105.4{deg}, b=+9.9{deg}, about 1.15kpc distant. Embedded within the reflection nebula is a young cluster dominated by a compact grouping of four early-type stars: BD+65{deg}1638 (B3V), BD+65{deg}1637 (B3e), SVS 13 (B5e), and LkH{alpha} 234 (B8e). About 80 H{alpha} emission sources brighter than V~23 are identified in the region, many of which are presumably T Tauri star members of the cluster. We also present deep (V~23), optical (VR_C_I_C_) photometry of a field centered on the reflection nebula and spectral types for more than 130 sources determined from low dispersion, optical spectroscopy. The narrow pre-main sequence evident in the color-magnitude diagram suggests that star formation was rapid and coeval. A median age of about 1.8Myr is inferred for the H{alpha} and literature-identified X-ray emission sources having established spectral types, using pre-main sequence evolutionary models. Our interpretation of the structure of the molecular cloud and the distribution of young stellar objects is that BD+65{deg}1638 is primarily responsible for evacuating the blister-like cavity within the molecular cloud. LkH{alpha} 234 and several embedded sources evident in near-infrared adaptive optics imaging have formed recently within the ridge of compressed molecular gas. The compact cluster of low-mass stars formed concurrently with the early-type members, concentrated within a central radius of ~0.7pc. Star formation is simultaneously occurring in a semi-circular arc some ~3pc in radius that outlines remaining dense regions of molecular gas. High dispersion, optical spectra are presented for BD+65{deg}1638, BD+65{deg}1637, SVS 13, LkH{alpha} 234, and V350 Cep. These spectra are discussed in the context of the circumstellar environments inferred for these stars.
4614. VRI photometry of Abell 3921 galaxies
ID:
ivo://CDS.VizieR/J/A+A/430/19
Title:
VRI photometry of Abell 3921 galaxies
Short Name:
J/A+A/430/19
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the analysis and results of a new VRI photometric and spectroscopic survey of the central ~1.8x1.2Mpc^2^ region of the galaxy cluster A3921 (z=0.094). We detect the presence of two dominant clumps of galaxies with a mass ratio of ~5: a main cluster centred on the Brightest Cluster Galaxy (BCG) (A3921-A), and an NW sub-cluster (A3921-B) hosting the second brightest cluster galaxy. The distorted morphology of the two sub-clusters suggests that they are interacting, while the velocity distribution of 104 confirmed cluster members does not reveal strong signatures of merging.
4615. VRI photometry of BL Lac (1997-1999)
ID:
ivo://CDS.VizieR/J/A+A/369/758
Title:
VRI photometry of BL Lac (1997-1999)
Short Name:
J/A+A/369/758
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the optical (V, R, and I) photometry for BL Lacertae, which was observed from 1997 through 1999, with the 1.56-m telescope at the Shanghai astronomical observatory (SHAO). After the 1997 outburst, it dimmed to a low state and then brightened again. During the period JD 2450701 to JD 2450701.5, variations of 0.40mag, 0.27mag, and 0.21mag over a time scale of 100min were found for V, R, and I bands, suggesting that the variations were decreasing with wavelength. The correlation between V, R, and I is also analyzed using the DCF (Discrete Correlation Function) method. This shows that the variability in the V, R, and I bands are correlated with no time delay longer than 0.2day.
4616. VRI photometry of IC5070 variable stars
ID:
ivo://CDS.VizieR/J/A+A/627/A135
Title:
VRI photometry of IC5070 variable stars
Short Name:
J/A+A/627/A135
Date:
21 Oct 2021
Publisher:
CDS
Description:
We observed a field of 16'x16' in the star-forming region Pelican Nebula (IC 5070) at BVRI wavelengths for 90 nights spread over one year in 2012-2013. More than 250 epochs in VRI-bands are used to identify and classify variables up to V~21mag. We present a catalogue of optical time-series photometry with periods, mean-magnitudes and classifications for 95 variable stars including 67 pre-main-sequence variables towards star-forming region IC 5070. The pre-main-sequence variables are further classified as candidate classical T Tauri and weak-line T Tauri stars based on their light curve variations and the locations on the color-color and color-magnitude diagrams using optical and infrared data together with Gaia DR2 astrometry. Classical T Tauri stars display variability amplitudes up to three times the maximum fluctuation in disk-free weak-line T Tauri stars, which show strong periodic variations. Short-term variability is missed in our photometry within single nights. Several classical T Tauri stars display long-lasting (>10 days) single or multiple fading and brightening events up to a couple of magnitudes at optical wavelengths.
4617. VRI photometry of {lambda} Ori PMS stars
ID:
ivo://CDS.VizieR/J/AJ/118/2409
Title:
VRI photometry of {lambda} Ori PMS stars
Short Name:
J/AJ/118/2409
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have found 72 premain-sequence (PMS) stars near the center of the {lambda} Orionis star-forming region by spectroscopically testing a magnitude-limited sample for the presence of lithium {lambda}6708 absorption, a diagnostic of youth. All of these stars show large lithium equivalent widths and radial velocities consistent with Orion membership, but only two were discovered previously via H{alpha} or X-ray surveys.
4618. VRI photometry of {lambda} Ori star-forming region
ID:
ivo://CDS.VizieR/J/AJ/123/387
Title:
VRI photometry of {lambda} Ori star-forming region
Short Name:
J/AJ/123/387
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present VRI photometry of 320,917 stars with 11<~R<~18 throughout the {lambda} Ori star-forming region. Using the more spatially limited spectroscopic surveys of Dolan & Mathieu (1999, Cat. <J/AJ/118/2409>, 2001, Cat. <J/AJ/121/2124>) to define the color-magnitude domain of young low-mass members of the association and removing statistically the field stars in this domain, we use our photometry to identify a representative pre-main-sequence (PMS) population throughout the interior of the molecular ring.
4619. VRI photometry of M35
ID:
ivo://CDS.VizieR/J/ApJ/546/1006
Title:
VRI photometry of M35
Short Name:
J/ApJ/546/1006
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present very deep and accurate photometry of the open cluster M35. We have observed this association in the Cousins R, I filters, together with the Johnson V filter. We have covered a region of 27.5x27.5 square arcmin, equivalent to a fifth of the total area of the cluster. The data range from I_c_=12.5 to 23.5mag, and the color intervals are 0.4<=(V-I)_c_<=3.0, 0.5<=(R-I)_c_<=2.5. Roughly, these values span from 1.6M_{sun}_ down to the substellar limit, in the case of cluster members. By using the location of the stars on color-magnitude and color-color diagrams, we have selected candidate members of this cluster. We have merged our sample with previously published data and obtained a color-magnitude diagram for the complete stellar population of the cluster, covering the spectral range early B-mid M. Based on the distribution of field and cluster stars in color-magnitude and color-color diagrams, we estimate that two-thirds of these candidates are likely to be true members of M35. These stars approximately double the number of stars identified as candidate members of this cluster (~2700). We provide the photometry and accurate positions of these stars.
4620. VRI photometry of M87 globular clusters
ID:
ivo://CDS.VizieR/J/AJ/115/1801
Title:
VRI photometry of M87 globular clusters
Short Name:
J/AJ/115/1801
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used the high-resolution camera at the Canada-France-Hawaii Telescope to obtain VRI photometry of the globular clusters in the innermost 140 of the M87 halo. The results are used to discuss several issues concerning the formation and evolution of globular cluster systems in supergiant elliptical galaxies like M87. Our principal results are as follows: (1) From our deep R-band photometry of the cluster population, we find no significant change in the globular cluster luminosity function (GCLF) with galactocentric radius, for cluster masses M>=10^5^M_{sun}_. This result places constraints on current theoretical predictions of the rate of cluster evolution by tidal shocking and evaporation, indicating that the main effects of dynamical evolution may be felt only on lower mass clusters (<~10^5^M_{sun}_) that are below the faint limit of most current observations. (2) Combining our V-I color indices with other data in the literature, we derive the metallicity gradient and mean metallicity of the clusters from r=9" out to r~500" (~0.7-35kpc). Within the core radius r_c_=1' of the globular cluster system, the metallicity distribution is uniform, but at larger radii the mean metallicity declines steadily as Z/Z_{sun}_~r^-0.9^. (3) The various options for explaining the existence of high specific frequency galaxies like M87 are evaluated. (4) We offer a new explanation for the large observed S_N_ range among the brightest cluster elliptical galaxies (BCGs). It is suggested that these central supergiant E galaxies formed in an exceptionally turbulent or high-density environment which favored a very rapid initial star formation burst. From a total sample of 30 BCGs, we derive empirical scaling relations that relate to this hypothesis. Our analysis favors the view that BCGs began forming at redshifts z>~5, distinctly earlier than most other galaxies.