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16961. VI photometry of HST faint field galaxies
ID:
ivo://CDS.VizieR/J/ApJ/453/48
Title:
VI photometry of HST faint field galaxies
Short Name:
J/ApJ/453/48
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a complete morphologically classified sample of 144 faint field galaxies from the HST Medium Deep Survey with 20.0=<Imag<22.0mag. We compare the global properties of the ellipticals and early- and late-type spirals and find a non-negligible fraction (13/144) of compact blue [(V-I)<1.0mag] systems with r^1/4^ profiles. We give the differential galaxy number counts for ellipticals and early-type spirals independently and find that the data are consistent with no-evolution predictions based on conventional flat Schechter luminosity functions (LFs) and a standard cosmology. Conversely, late-type/irregulars show a steeply rising differential number count with slope ({delta}logN/{delta}m)=0.64+/-0.1. No-evolution models based on the Loveday et al. (1992ApJ...390..338L) and Marzke et al. (1994AJ....108..437M & 1994ApJ...428...43M) local luminosity functions underpredict the late-type/irregular counts by 1.0 and 0.5dex, respectively, at Imag=21.75mag. Examination of the irregulars alone shows that ~50% appear inert and the remainder have multiple cores. If the inert galaxies represent a non-evolving late-type population, then a Loveday-like LF ({alpha}=~-1.0) is ruled out for these types, and an LF with a steep faint end ({alpha}=~-1.5) is suggested. If multiple core structure indicates recent star formation, then the observed excess of faint blue field galaxies is likely a result of et evolutionary processes acting on a steep field LF for late-type/irregulars. The evolutionary mechanism is unclear, but 60% of the multiple-core irregulars show close companions. To reconcile a Marzke-like LF with the faint redshift surveys, this evolution must be preferentially occurring in the brightest late-type galaxies with z>=0.5 at m_I_=21.75mag.
16962. VI photometry of M15 core
ID:
ivo://CDS.VizieR/J/MNRAS/423/2260
Title:
VI photometry of M15 core
Short Name:
J/MNRAS/423/2260
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present high-resolution I-band imaging of the core of the globular cluster M15 obtained at the 2.5-m Nordic Optical Telescope with FastCam, a low readout noise L3CCD-based instrument. Short exposure times (30ms) were used to record 200000 images (512x512 pixels each) over a period of 2h and 43min. The lucky imaging technique was then applied to generate a final image of the cluster centre with full width at half-maximum ~0.1arcsec and 13x13arcsec^2^ field of view. We obtained a catalogue of objects in this region with a limiting magnitude of I=19.5. I-band photometry and astrometry are reported for 1181 stars. This is the deepest I-band observation of the M15 core at this spatial resolution.
16963. VI photometry of MM1 and MM7 OGLE fields
ID:
ivo://CDS.VizieR/J/AcA/53/27
Title:
VI photometry of MM1 and MM7 OGLE fields
Short Name:
J/AcA/53/27
Date:
21 Oct 2021
Publisher:
CDS
Description:
As a result of the reanalysis of the OGLE-I observations by means of the image subtraction method, we present the first part of a catalog, consisting of data for variable stars in four Galactic fields observed by OGLE-I, viz. MM1-A, MM1-B, MM7-A, and MM7-B. In total, 2016 variable stars have been found. This increased the number of known variable stars in these fields more than twofold. We comment on the detectability of the variable stars in previous studies.
16964. VI photometry of M33 star clusters
ID:
ivo://CDS.VizieR/J/A+A/366/498
Title:
VI photometry of M33 star clusters
Short Name:
J/A+A/366/498
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have detected 102 star clusters in M 33, from 35 deep Hubble Space Telescope (HST) WFPC2 fields taken from our program and from the HST archive. Twenty-eight fields have V and I band imaging, and an additional seven fields are imaged in a single V filter. Eighty-two of the clusters were previously unknown. Integrated photometry reveals that 25 clusters have (V-I) colors typical of those found in Galactic globular clusters (only ten of these objects were previously known). Our discovery of 15 new globular cluster candidates increases previous estimates of the old cluster population in M 33 by ~60%. An additional eleven objects (only two were previously known) have colors expected for intermediate age clusters. The new clusters have a range of ages from 6 million years to >15Gyrs, and masses between 10^2^M_{sun}_-10^6^M_{sun}_, although these parameters are estimated from only one color.
16965. VI photometry of new Cepheids in NGC 3198
ID:
ivo://CDS.VizieR/J/ApJ/514/614
Title:
VI photometry of new Cepheids in NGC 3198
Short Name:
J/ApJ/514/614
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the detection of Cepheid variable stars and a new distance to the Sc spiral NGC 3198. NGC 3198 is one of 25 galaxies that have been observed with the WFPC2 of the Hubble Space Telescope (HST) for the purpose of measuring Cepheid distances. Eighteen of these galaxies were targeted by the HST Key Project on the Extragalactic Distance Scale, whose objective is to calibrate a variety of secondary distant indicators and determine the Hubble constant to an accuracy of 10%. NGC 3198 was selected as part of this sample because its type and orientation make it very suitable as a Tully-Fisher calibrator. The WFPC2 data are comprised of 13 epochs in F555W ({~}V) and five epochs in F814W ({~}I). Two different crowded-field photometry packages (DAOPHOT/ALLFRAME and DoPHOT) were used. The magnitudes derived from these two packages agree to within a few percent. We identified 78 Cepheid candidates in the period range from eight to >50 days, of which 52 were selected for establishing the distance modulus. Period-luminosity relations were constructed in Johnson V and Kron-Cousins I by transforming the F555W and F814W to the standard system. We adopted a distance modulus of {mu}_o_=18.50{+/-}0.10 mag and mean reddening of E(B-V)=0.10 mag to the Large Magellanic Cloud Cepheids and found a true distance modulus to NGC 3198 of {mu}_o_=30.80{+/-}0.16 (random) {+/-}0.12 (systematic) mag. This modulus corresponds to a distance of 14.5 Mpc, with random and systematic errors of {+/-}1.2 and {+/-}0.9 Mpc, respectively.
16966. VI photometry of new Cepheids in NGC 3319
ID:
ivo://CDS.VizieR/J/ApJ/523/540
Title:
VI photometry of new Cepheids in NGC 3319
Short Name:
J/ApJ/523/540
Date:
21 Oct 2021
Publisher:
CDS
Description:
The distance to NGC 3319 has been determined from Cepheid variable stars as part of the Hubble Space Telescope Key Project on the Extragalactic Distance Scale. Thirteen and four epochs of observations, using filters F555W (V) and F814W (I), respectively, were made with the Wide Field Planetary Camera 2. Thirty-three Cepheid variables between periods of 8 and 47 days were discovered. Adopting a Large Magellanic Cloud distance modulus of 18.50{+/-}0.10 mag and extinction of E(V-I)=0.13 mag, a true reddening-corrected distance modulus (based on an analysis employing the ALLFRAME software package) of 30.78 {+/-}0.14 (random) {+/-}0.10 (systematic) mag and the extinction of E(V-I)=0.06 mag were determined for NGC 3319. This galaxy is the last galaxy observed for the HST H_o_ Key Project.
16967. VI photometry of new Cepheids in NGC 4725
ID:
ivo://CDS.VizieR/J/ApJ/512/48
Title:
VI photometry of new Cepheids in NGC 4725
Short Name:
J/ApJ/512/48
Date:
21 Oct 2021
Publisher:
CDS
Description:
The distance to NGC 4725 has been derived from Cepheid variables as part of the Hubble Space Telescope Key Project on the Extragalactic Distance Scale. Thirteen F555W (V) and four F814W (I) epochs of cosmic-ray-split Wide Field and Planetary Camera 2 observations were obtained. Twenty Cepheids were discovered, with periods ranging from 12 to 49 days. Adopting a Large Magellanic Cloud distance modulus and extinction of 18.50{+/-}0.10 mag and E(V-I)=0.13 mag, respectively, a true reddening-corrected distance modulus (based on an analysis employing the ALLFRAME software package) of 30.50{+/-}0.16 (random) {+/-}0.17 (systematic) mag was determined for NGC 4725. The corresponding of distance of 12.6{+/-}1.0 (random) {+/-}1.0 (systematic) Mpc is in excellent agreement with that found with an independent analysis based upon the DoPHOT photometry package. With a foreground reddening of only E(V-I)=0.02, the inferred intrinsic reddening of this field in NGC 4725, E(V-I)=0.19, makes it one of the most highly reddened fields encountered by the HST Key Project to date.
16968. VI photometry of new Cepheids in NGC 2541
ID:
ivo://CDS.VizieR/J/ApJ/507/655
Title:
VI photometry of new Cepheids in NGC 2541
Short Name:
J/ApJ/507/655
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the detection of Cepheids and a new distance to the spiral galaxy NGC 2541, based on data obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope (HST). A total of 25 exposures (divided into 13 epochs) were obtained using the F555W filter (transformed to Johnson V), and nine exposures were obtained (divided into five epochs) using the F814W filter (transformed to Cousins I). Photometric reduction of the data is performed using two independent packages, DoPHOT and DAOPHOT II/ALLFRAME, which give very good agreement in the measured magnitudes. A total of 34 bona fide Cepheids, with periods ranging from 12 to over 60 days, are identified based on both sets of photometry. By fitting V and I period-luminosity relations, apparent distance moduli are derived assuming a Large Magellanic Cloud distance modulus and mean color excess of {mu}_LMC_=18.50+/-0.10mag and E(B-V)=0.10mag, respectively. Adopting A(V)/E(V-I)=2.45, we obtain a true distance modulus to NGC 2541 of {mu}_0_=30.47+/-0.11 (random) +/-0.12 (systematic) mag (D=12.4+/-0.6 [random] +/-0.7 [systematic] Mpc), and a total (Galactic plus internal) mean color excess E(B-V)=0.08+/-0.05 (internal error) mag.
16969. VI photometry of new M53 variables
ID:
ivo://CDS.VizieR/J/A+A/507/803
Title:
VI photometry of new M53 variables
Short Name:
J/A+A/507/803
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the variable star content of the globular cluster M53 to compute the physical parameters of the constituting stars and the distance of the cluster. Covering two adjacent seasons in 2007 and 2008, new photometric data are gathered for 3048 objects in the field of M53. By using the OIS (optimal image subtraction) method and subsequently TFA (trend filtering algorithm), we search for variables in the full sample by using discrete Fourier transformation and box-fitting least squares method. We select variables based on the statistics related to these methods combined with visual inspection. We identified 12 new variables (2 RR Lyrae stars, 7 short periodic stars - 3 of them are SX Phe stars - and 3 long-period variables). No eclipsing binaries were found in the present sample. Except for the 3 (hitherto unknown) Blazhko RR Lyrae (two RRab and an RRc) stars, no multiperiodic variables were found. We showed that after proper period shift, the PLC (period-luminosity-color) relation for the first overtone RR Lyrae sample tightly follows the one spanned by the fundamental stars. Furthermore, the slope is in agreement with that derived from other clusters. Based on the earlier Baade-Wesselink calibration of the PLC relations, the derived reddening-free distance modulus of M53 is 16.31+/-0.04mag, corresponding to a distance modulus of 18.5mag for the Large Magellanic Cloud. From the Fourier parameters of the RRab stars we obtained an average iron abundance of -1.58+/-0.03 (error of the mean). This is ~0.5dex higher than the overall abundance of the giants as given in the literature and derived in this paper from the three-color photometry of giants. We suspect that the source of this discrepancy (observable also in other, low-metallicity clusters) is the lack of a sufficient number of low-metallicity objects in the calibrating sample of the Fourier method.
16970. VI photometry of NGC 5634
ID:
ivo://CDS.VizieR/J/AJ/124/915
Title:
VI photometry of NGC 5634
Short Name:
J/AJ/124/915
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first (V, V-I) color-magnitude diagram (CMD) for the poorly studied globular cluster NGC 5634. The CMD shows a steep red giant branch (RGB) and a predominantly blue horizontal branch (HB): both these characteristics suggest a low metal content for this cluster. The data were obtained at the 3.52 m Italian Telescopio Nazionale Galileo (Roque de los Muchachos, La Palma, Canary Islands, Spain), using the LSR DoLoRes Camera equipped with a 2048x2048 pixel thinned and back-illuminated Loral CCD array.

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