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4361. NGC 4038/4039 broad and /narrow band photometry
ID:
ivo://CDS.VizieR/J/A+A/443/41
Title:
NGC 4038/4039 broad and /narrow band photometry
Short Name:
J/A+A/443/41
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Ks-band image which was used for the 3{sigma}-detection was obtained with ISAAC on VLT-ANTU as part of programme 65.N-0577, and has a FWHM of ~0.38". 1072 point-like objects were detected. For the multi-band photometry, we also used the HST archival images obtained by Whitmore et al. (see Whitmore et al., 1999AJ....118.1551W), which we rebinned to the same pixel size as the ISAAC image (0.1484"/pix). The CO narrow band image was also obtained with ISAAC, while the Br{gamma} image was obtained with SOFI at the NTT (programme number 63.N-0528). The Br{gamma} image had a lower image quality than the other two images (FWHM=0.7"). The photometry data were used to simultaneously fit age and extinction for each individual cluster in comparison to an evolutionary synthesis model. Where possible, the visual extinction was determined from an average of the extinction from the broadband fit and from the Hydrogen recombination line ratios (in comparison to the expected Case B line ratio). The age estimate from the fit was, where possible, averaged with the aged determined from equivalent widths and CO index.
4362. NGC 2213 BR photometry
ID:
ivo://CDS.VizieR/J/ApJ/297/582
Title:
NGC 2213 BR photometry
Short Name:
J/ApJ/297/582
Date:
21 Oct 2021
Publisher:
CDS
Description:
The age of the LMC red globular cluster NGC 2213 has been estimated as 1.3+/-0.5x10^9^yr from a color-magnitude diagram, derived from CCD photometry, that reveals the cluster main sequence. The accuracy of the age estimate, however, is limited by uncertainly in the LMC distance modulus, by uncertainty in the cluster metal abundance which appears to lie in the range one-half to one-sixth solar, by uncertainty in the reddening of the cluster, and by uncertainty in the extent to which the theoretical isochrones used for the age dating are affected by the neglect, in standard stellar models, of the interior mixing caused by convective overshoot in the stellar cores. Using the adopted reddening of E(B-V)=0.09 and assuming Y=0.2, isochrone best fits to the cluster main sequence are found for [M/H]=-0.3 if (m-M)0=18.7 and for [M/H]=-0.7 if (m-M)0=18.2. After allowance for the possible effects of convective overshoot, the corresponding ages are 0.9^+0.5^_-0.3_ and 1.6^+0.8_^-0.4_x10^9^yr. Plausible alterations in the adopted reddening value and the adopted helium abundance also yield ages within these limits.
4363. NGC 121 BR photometry
ID:
ivo://CDS.VizieR/J/ApJ/298/544
Title:
NGC 121 BR photometry
Short Name:
J/ApJ/298/544
Date:
21 Oct 2021
Publisher:
CDS
Description:
The age of the SMC globular cluster NGC 121 is found from main-sequence isochrone fitting to be 12+/-2x10^9^yr if a distance modulus that assumes Mv=+0.6 for the field RR Lyrae variables near the cluster is used. If instead (m-M)o = 19.3, then the cluster age is 9+/-2x10^9^yr. The cluster is known to contain both RR Lyrae variables and a marginal carbon star; comparison with theoretical models indicates no significant inconsistencies in this joint occurrence at either modulus. The color-magnitude diagram for the nearby field also shows a faint, blue main-sequence turnoff and, in contrast to previous Magellanic Cloud field studies, the field lacks any evidence for the existence of a significant intermediate-age component. A new look at the chemical evolution of the Small Magellanic Cloud suggests that, unlike the Galaxy, where the rate of enrichment has been steady after the initial phase, the enrichment in the SMC remained small for a long interval before increasing rapidly sometime in the last 1-2x10^9^yr.
4364. NGC 5548 BR photometry
ID:
ivo://CDS.VizieR/J/AJ/116/102
Title:
NGC 5548 BR photometry
Short Name:
J/AJ/116/102
Date:
21 Oct 2021
Publisher:
CDS
Description:
Deep Hubble Space Telescope Wide Field Camera (WFC-1) imaging of a region 3.7' east of the V=13mag Seyfert galaxy NGC 5548 in the F555W and F785LP bands, and deep ground-based V and I imaging, show a new extended, blue, low surface brightness structure, apparently a remnant of a tidal interaction associated with NGC 5548. If this straight, low surface brightness (V~27-28mag/arcsec^2^) tidal tail is associated with NGC 5548, it extends at least 80kpc from it and has an absolute magnitude of M_V~-16.4 (H_0_=65km/s/Mpc). Previous imaging surveys of Seyfert galaxies would have missed such low surface brightness tails. Morphologically similar to some brighter tails seen in other interacting systems and in simulations of merging galaxies, this faint tail is a useful diagnostic of an earlier interaction and of the progenitors' halo-to-disk mass ratios. Luminous ripples and a brighter tail wrapped around the galaxy are seen in the inner 1-10kpc region. Unresolved blue objects in the long tail have the colors and absolute magnitudes of young globular clusters. Taken together, the two tails and other features suggest that two spirals merged less than ~1Gyr ago. The inner luminosity profile of NGC 5548 is a good fit to a de Vaucouleurs profile with r_eff_=5.8kpc. Recent simulations of merged galaxies with high-mass halos fail to form lasting tidal tails, suggesting that the NGC 5548 progenitor spirals had modest halo masses.
4365. NGC 6401 bulge variable stars
ID:
ivo://CDS.VizieR/J/MNRAS/465/2489
Title:
NGC 6401 bulge variable stars
Short Name:
J/MNRAS/465/2489
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of variable stars in globular cluster NGC 6401. The cluster is only 5.3{deg} away from the Galactic Centre and suffers from strong differential reddening. The photometric precision afforded us by difference image analysis resulted in improved sensitivity to variability in formerly inaccessible interior regions of the cluster. We find 23 RRab and 11 RRc stars within one cluster radius (2.4-arcmin), for which we provide coordinates, finder-charts and time series photometry. Through Fourier decomposition of the RR Lyrae star light curves we derive a mean metallicity of [Fe/H]UVES=-1.13+/-0.06 ([Fe/H]ZW=-1.25+/-0.06), and a distance of d~6.35+/-0.81kpc. Using the RR Lyrae population, we also determine that NGC 6401 is an Oosterhoff type I cluster.
4366. NGC 6535 BV CCD photometry
ID:
ivo://CDS.VizieR/J/PASP/106/404
Title:
NGC 6535 BV CCD photometry
Short Name:
J/PASP/106/404
Date:
21 Oct 2021
Publisher:
CDS
Description:
The first CCD color-magnitude diagram (CMD) in B and V is presented for the Galactic globular cluster NGC 6535. From this CMD, which extends below the main-sequence turnoff, we draw the following conclusions: (1) The horizontal branch (HB) is predominantly blue in nature with no RR Lyrae variables known to be cluster members. Nonetheless, based on a comparison with clusters which have blue HBs and RR Lyraes (M15 and M79), we infer a mean HB magnitude of <V(RR)>=15.73+/-0.11 for NGC 6535. (2) Again, via a direct comparison with the blue HBs of M15 and M79, we derive a cluster reddening of E(B-V)=0.44+/-0.02. (3) When combined with the apparent color of the red-giant branch at the level of the HB, (B-V)g=1.18+/-0.02, the derived reddening yields a metal abundance of [Fe/H]=-1.85+/-0.10, similar to that of NGC 6397. (4) Application of the Delta(V(TO-HB)) and Delta((B-V)(SGB-TO)) cluster dating techniques reveals no perceptible age difference between NGC 6535 and NGC 6397. (5) A significant population of nine blue-straggler candidates is detected in NGC 6535. However, this is too few to facilitate a meaningful analysis of their radial distribution.
4367. NGC 2282 BVI Ha observations
ID:
ivo://CDS.VizieR/J/MNRAS/454/3597
Title:
NGC 2282 BVI Ha observations
Short Name:
J/MNRAS/454/3597
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the analysis of the stellar content of NGC 2282, a young cluster in the Monoceros constellation, using deep optical BVI and INT Photometric H{alpha} Survey (IPHAS) photometry along with infrared (IR) data from UKIRT Infrared Deep Sky Survey and Spitzer-IRAC. Based on the stellar surface density analysis using nearest neighbourhood method, the radius of the cluster is estimated as ~3.15-arcmin. From optical spectroscopic analysis of eight bright sources, we have classified three early B-type members in the cluster, which includes, HD 289120, a previously known B2V-type star, a Herbig Ae/Be star (B0.5 Ve) and a B5 V star. From spectrophotometric analyses, the distance to the cluster has been estimated as ~1.65kpc. The K-band extinction map is estimated using nearest neighbourhood technique, and the mean extinction within the cluster area is found to be A_V_~3.9mag. Using IR colour-colour criteria and H{alpha}-emission properties, we have identified a total of 152 candidate young stellar objects (YSOs) in the region, of which, 75 are classified as Class II, nine are Class I YSOs. Our YSO catalogue also includes 50 H{alpha}-emission line sources, identified using slitless spectroscopy and IPHAS photometry data. Based on the optical and near-IR colour-magnitude diagram analyses, the cluster age has been estimated to be in the range of 2-5Myr, which is in agreement with the estimated age from disc fraction (~58 per cent). Masses of these YSOs are found to be ~0.1-2.0M_{sun}_. Spatial distribution of the candidate YSOs shows spherical morphology, more or less similar to the surface density map.
4368. NGC 1316 BVI images
ID:
ivo://CDS.VizieR/J/A+A/552/A106
Title:
NGC 1316 BVI images
Short Name:
J/A+A/552/A106
Date:
21 Oct 2021
Publisher:
CDS
Description:
The distance of NGC1316, the brightest galaxy in the Fornax cluster, provides an interesting test for the cosmological distance scale. First, because Fornax is the second largest cluster of galaxies within <~25Mpc after Virgo and, in contrast to Virgo, has a small line-of-sight depth; and second, because NGC1316 is the single galaxy with the largest number of detected Type Ia supernovae (SNe Ia), giving the opportunity to test the consistency of SNe Ia distances both internally and against other distance indicators. We measure surface brightness fluctuations (SBF) in NGC1316 from ground- and space-based imaging data. The sample provides a homogeneous set of measurements over a wide wavelength interval. The SBF magnitudes, coupled with empirical and theoretical absolute SBF calibrations, are used to estimate the distance to the galaxy. We also present the first B-band SBF measurements of NGC1316 and use them together with the optical and near-IR SBF data to analyze the properties of field stars in the galaxy. We obtain m-M=31.59+/-0.05(stat)+/-0.14(sys.)mag, or d=20.8+/-0.5(stat)+/-1.5(sys.)Mpc. When placed in a consistent Cepheid distance scale, our result agrees with the distances from other indicators. On the other hand, our distance is ~17% larger than the most recent estimate based on SNe Ia. Possible explanations for this disagreement are the uncertain level of internal extinction, and/or calibration issues. Concerning the stellar population analysis, we confirm the results from other spectro-photometric indicators: the field stars in NGC1316 are dominated by a component with roughly solar metallicity and intermediate age. A non-negligible mismatch exists between B-band SBF models and data. We confirm that such behavior can be accounted for by an enhanced percentage of hot horizontal branch stars. Our study of the SBF distance to NGC1316, and the comparison with distances from other indicators, raises some concern about the homogeneity between the calibrations of different indicators. If not properly placed in the same reference scale, significant differences can occur, with dramatic impact on the cosmological distance ladder. Our results on the stellar populations properties show that SBF data over a broad wavelength interval are an efficient means of studying the properties of unresolved systems in peculiar cases like NGC1316.
4369. NGC 2355 BVI photometry
ID:
ivo://CDS.VizieR/J/MNRAS/453/4185
Title:
NGC 2355 BVI photometry
Short Name:
J/MNRAS/453/4185
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper we analyse the evolutionary status and properties of the old open cluster NGC 2355, located in the Galactic anticentre direction, as a part of the long-term programme Bologna Open Clusters Chemical Evolution. NGC 2355 was observed with the Large Binocular Camera at the Large Binocular Telescope using the Bessel B, V, and Ic filters. The cluster parameters have been obtained using the synthetic colour-magnitude diagram method, as done in other papers of this series. Additional spectroscopic observations with the Fibre-fed Echelle Spectrograph at the Nordic Optical Telescope of three giant stars were used to determine the chemical properties of the cluster. Our analysis shows that NGC 2355 has metallicity slightly less than solar, with [Fe/H]=-0.06dex, age between 0.8 and 1Gyr, reddening E(B-V) in the range 0.14-0.19mag, and distance modulus (m-M)0 of about 11mag. We also investigate the abundances of O, Na, Al, {alpha}, iron-peak, and neutron capture elements, showing that NGC 2355 falls within the abundance distribution of similar clusters (same age and metallicity). The Galactocentric distance of NGC 2355 places it at the border between two regimes of metallicity distribution; this makes it an important cluster for the study of the chemical properties and evolution of the disc.
4370. NGC 6144 BVI photometry
ID:
ivo://CDS.VizieR/J/AJ/119/1793
Title:
NGC 6144 BVI photometry
Short Name:
J/AJ/119/1793
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present CCD photometry in the BVI-filter passbands for the Galactic globular cluster NGC 6144. This cluster is located in the direction of the {rho} Ophiuchi dust cloud, approximately 30 northwest of the bright star {alpha} Scorpii (Antares). Our color-magnitude diagrams (CMDs) of NGC 6144 extend from above the tip of the first-ascent red giant branch (RGB) to ~3mag below the horizontal branch (HB). The morphology of the HB is predominantly blueward of the RR Lyrae instability strip, while the RGB is relatively steep, signifying a low-to-intermediate metal abundance. Our CMD also reveals the presence of three candidate post-asymptotic giant branch stars. We find VHB=16.30+/-0.07; coupling the measured RGB color at the level of the HB with a polynomial describing the shape of the RGB, we have utilized the simultaneous reddening and metallicity method of Sarajedini to estimate a metallicity of [Fe/H]=-1.81+/-0.12 (on the Zinn & West, 1984ApJS...55...45Z, scale) and a mean reddening of E(B-V)=0.41+/-0.02. In addition to this mean level, our observations reveal that the reddening has a spatially variable component generally increasing from north to south consistent with the expected density variations in the {rho} Ophiuchi dust cloud.