- ID:
- ivo://CDS.VizieR/J/A+A/592/A20
- Title:
- NGC 1316 and NGC 612 WISE images
- Short Name:
- J/A+A/592/A20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Most radio galaxies are hosted by giant gas-poor ellipticals, but some contain significant amounts of dust, which is likely to be of external origin. In order to characterize the mid-IR properties of two of the most nearby and brightest merger-remnant radio galaxies of the Southern hemisphere, NGC 1316 (Fornax A) and NGC 612 (PKS 0131-36), we used observations with the Wide-field Infrared Survey Explorer (WISE) at wavelengths of 3.4, 4.6, 12 and 22 micron and Spitzer mid-infrared spectra. By applying a resolution-enhancement technique, new WISE images were produced at angular resolutions ranging from 2.6" to 5.5". Global measurements were performed in the four WISE bands, and stellar masses and star-formation rates were estimated using published scaling relations. Two methods were used to uncover the distribution of dust, one relying on two-dimensional fits to the 3.4 micron images to model the starlight, and the other one using a simple scaling and subtraction of the 3.4 micron images to estimate the stellar continuum contribution to the emission in the 12 and 22 micron bands. The two galaxies differ markedly in their mid-IR properties. The 3.4 micron brightness distribution can be well represented by the superposition of two Sersic models in NGC 1316 and by a Sersic model and an exponential disk in NGC 612. The WISE colors of NGC 1316 are typical of those of early-type galaxies; those of NGC 612 are in the range found for star-forming galaxies. From the 22 micron luminosity, we infer a star-formation rate of about 0.7 solar masses per year in NGC 1316 and about 7 solar masses per year in NGC 612. Spitzer spectroscopy shows that the 7.7-to-11.3 micron PAH line ratio is significantly lower in NGC 1316 than in NGC 612. The WISE images reveal resolved emission from dust in the central 1'-2' of the galaxies. In NGC 1316, the extra-nuclear emission coincides with two dusty regions NW and SE of the nucleus seen in extinction in optical images and where molecular gas is known to reside. In NGC 612 it comes from a warped disk. This suggests a recent infall onto NGC 1316 and disruption of one or several smaller gas-rich galaxies, but a smoother accretion in NGC 612. While the nucleus of NGC 1316 is currently dormant and the galaxy is likely to evolve into a passive elliptical, NGC 612 has the potential of growing a larger disk and sustaining an active nucleus. NGC 1316 and NGC 612 represent interesting challenges to models of formation and evolution of galaxies and AGNs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/671/605
- Title:
- NGC 2264 and ONC PMS stars in the infrared
- Short Name:
- J/ApJ/671/605
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of pre-main-sequence star rotation periods reveal slow rotators in young clusters of various ages, indicating that angular momentum is somehow removed from these rotating masses. The mechanism by which spin-up is regulated as young stars contract has been one of the longest standing problems in star formation. Attempts to observationally confirm the prevailing theory that magnetic interaction between the star and its circumstellar disk regulates these rotation periods have produced mixed results. In this paper, we use the unprecedented disk identification capability of the Spitzer Space Telescope to test the star-disk interaction paradigm in two young clusters, NGC 2264 and the Orion Nebula Cluster (ONC).
- 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.
1984. 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.
- ID:
- ivo://CDS.VizieR/J/AJ/106/66
- Title:
- NGC 1560 BVRI CCD photometry
- Short Name:
- J/AJ/106/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present BVRI CCD photometry of ~600 stars in the central region of a resolved spiral galaxy NGC 1560 which is seen almost edge-on, apparently located in the IC 342 group. The V-(B-V) diagram shows a dominant group of significantly reddened blue plume stars consisting of young massive main-sequence and evolved blue supergiant stars. The tip of the blue plume is found to be at V~21 mag and (B-V)~0.4mag. The I-(R-I) diagram shows a large group of red supergiants the brightest of which are extending to I~19.5mag at (R-I)~1.1mag. The logarithmic slope of the V luminosity function of the blue plume stars is 0.69+/-0.10, similar to that for other nearby galaxies. The mean color of the blue plume stars is <(B-V)>=0.25+/-0.03mag. The total reddening, including both foreground and internal reddening, is estimated from the mean color of the blue plume stars, to be E(B-V)=0.40+/-0.10mag, whereas the foreground reddening based on the H I column density and faint galaxy counts is E(B-V)=0.16mag. Combining our results with those in the literature, we have obtained distance estimates using four methods: brightest blue stars [(m-M)_0_=27.11mag], brightest red stars [(m-M)_0_=27.02mag], B-band Tully-Fisher relation [(m-M)_0_=26.96mag], and H-band Tully-Fisher relation [(m-M)_0_=26.86mag]. These four estimates agree very well. Taking the average of these four estimates, we obtain a value for the true distance modulus to NGC 1560, (m-M)_0_=27.0+/-0.1mag, corresponding to a distance of 2.5+/-0.1Mpc.
- ID:
- ivo://CDS.VizieR/J/PASP/117/22
- Title:
- NGC 6318 CCD BVI photometry
- Short Name:
- J/PASP/117/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD BVI photometry for the southern open cluster NGC 6318. The sample consists of 9876 stars measured in an area of 13.6'x13.6', extending down to V~21.5mag. Star counts carried out within and outside the cluster region allowed us to estimate the cluster angular radius as 8'.
1987. NGC 6994 CCD photometry
- ID:
- ivo://CDS.VizieR/J/A+A/355/138
- Title:
- NGC 6994 CCD photometry
- Short Name:
- J/A+A/355/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- BVRI CCD photometry of 144 stars in the region of NGC 6994: positions, V magnitudes, (B-V), (V-R) and (V-I) colors.
- ID:
- ivo://CDS.VizieR/J/other/ApSS/361.126
- Title:
- NGC 6819 CCD UBV photometry
- Short Name:
- J/other/ApSS/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of CCD UBV observations of the open cluster NGC 6819. We calculated the stellar density profile in the cluster's field to determine the structural parameters of NGC 6819. Using the existing astrometric data, we calculated the probabilities of the stars being physical members of the cluster, and used these objects in the determination of the astrophysical parameters of NGC 6819. We inferred the reddening and metallicity of the cluster as E(B-V)=0.130+/-0.035mag and [Fe/H]=+0.051+/-0.020dex, respectively, using the U-B vs B-V two-colour diagram and UV excesses of the F-G type main-sequence stars. We fit the colour-magnitude diagrams of NGC 6819 with the PARSEC isochrones and derived the distance modula, distance and age of the cluster as mu_V=12.22+/-0.10mag, d=2309+/-106pc and t=2.4+/-0.2Gyr, respectively. The parameters of the galactic orbit estimated for NGC 6819 indicate that the cluster is orbiting in a slightly eccentric orbit of e=0.06 with a period of P_orb_=142Myr. The slope of the mass function estimated for the cluster is close to the one found for the stars in the solar neighbourhood.
- ID:
- ivo://CDS.VizieR/J/other/ApSS/355.267
- Title:
- NGC 6811 CCD UBVRI photometry
- Short Name:
- J/other/ApSS/355
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of CCD UBVRI observations of the open cluster NGC 6811 obtained on 18th July 2012 with the 1m telescope at the TIBITAK National Observatory (TUG). Using these photometric results, we determine the structural and astrophysical parameters of the cluster. The mean photometric uncertainties are better than 0.02 mag in the V magnitude and B-V, V-R, and V-I colour indices to about 0.03mag for U-B among stars brighter than magnitude V=18. Cluster member stars were separated from the field stars using the Galaxia model of Sharma et al. (2011ApJ...730....3S) together with other techniques. The core radius of the cluster is found to be r_c_=3.60arcmin. The astrophysical parameters were determined simultaneously via Bayesian statistics using the colour-magnitude diagrams V versus B-V, V versus V-I, V versus V-R, and V versus R-I of the cluster. The resulting most likely parameters were further confirmed using independent methods, removing any possible degeneracies. The colour excess, distance modulus, metallicity and the age of the cluster are determined simultaneously as E(B-V)=0.05+/-0.01mag, {mu}=10.06+/-0.08mag, [M/H]=-0.10+/-0.01dex and t=1.00+/-0.05Gyr, respectively. Distances of five red clump stars which were found to be members of the cluster further confirm our distance estimation.
- ID:
- ivo://CDS.VizieR/J/PASP/110/1318
- Title:
- NGC 7789 CCD VI photometry
- Short Name:
- J/PASP/110/1318
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A V, V-I-diagram for the intermediate-age open cluster NGC 7789 has been derived from CCD observations of more than 15,000 stars within ~18' of the cluster center. From the brightest giants and blue stragglers at V~11 to the faintest lower main-sequence stars that were observed (at V~21, M_V_~9), the color-magnitude diagram is well defined. A prominent clump of core helium-burning stars is evident at V=13.0, and the upper end of the main sequence shows a fairly pronounced curvature to the red, which is indicative of significant convective core overshooting. Indeed, comparisons with up-to-date stellar models show that it is not possible to explain the observed morphology in the vicinity of the turnoff unless the overshooting is quite extensive. Interestingly, if sufficient overshooting is assumed in order to match the main-sequence data, it is not possible to reproduce the cluster's extended giant branch unless the cluster age is at least 1.6 Gyr (assuming a metallicity in the range -0.2<=[FeMH]<=0.0). This, in turn, requires that the cluster have an apparent distance modulus m-M_V_<=12.2. Thus, sometime within the past few hundred million years, the ignition of helium burning in NGC 7789 has switched from a quiescent to an explosive ("flash") phenomenon, and the length of the cluster's red giant branch has been steadily increasing with the passage of time since then. From main-sequence fits to models that have been carefully normalized to the Sun, we infer a reddening 0.35<=E(V-I)<=0.38.
