- ID:
- ivo://CDS.VizieR/J/MNRAS/503/236
- Title:
- UVIT catalog and membership of 6 open clusters
- Short Name:
- J/MNRAS/503/236
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of six open clusters (Berkeley 67, King 2, NGC 2420, NGC 2477, NGC 2682 and NGC 6940) using the Ultra Violet Imaging Telescope (UVIT) aboard ASTROSAT and Gaia EDR3. We present their Gaia EDR3 membership catalogues and UV photometric catalogues along with membership probability. We used a supervised machine learning algorithm along with a Gaussian mixture model and used combinations of astrometric, photometric and systematic parameters to train the algorithm. We classified the stars as members, candidates and field using two such combinations. This generic technique is robust, reproducible, versatile in various cluster environments and is applicable to other data-sets. We could detect 200-2500 additional members using this method with respect to Gaia DR2 studies. We estimated cluster properties such as mean space velocities, distances, number of members and core radii. We detected 3 to 700 member stars, which include blue stragglers, main-sequence and red giants in various UVIT images of six clusters. We created UV-Optical colour-magnitude diagrams to find that majority of the sources in NGC 2682 and a few in NGC 2420, NGC 2477 and NGC 6940 showed excess UV flux. NGC 2682 images have 10 white dwarf detections in far-UV. The massive cluster NGC 2477 has 92/576 members detected in the far-UV/near-UV, which will be useful to study the UV properties of stars in the extended turn-off and in various evolutionary stages from main-sequence to red clump. Future studies will carry out panchromatic analysis of noteworthy members detected in this study.
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- ID:
- ivo://CDS.VizieR/J/A+A/369/812
- Title:
- UVKs photometry of globular clusters in NGC 5128
- Short Name:
- J/A+A/369/812
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- At the distance of NGC 5128 (3.6+/-0.2Mpc) it is possible to resolve globular clusters with high resolution imaging from the ground, thus allowing the globular cluster candidate selection primarily through their morphological properties. I report the discovery of 71 globular clusters in NGC 5128 on VLT UT1+FORS1 images, including the faintest members (M_V_~-5) known to date in this galaxy as well as in 5 previously-known clusters. U- and V-band photometry has been measured for all the candidates and the luminosity function, spanning -10.1<M_V_<-4.9 and -9.3<M_U_<-3.3, constructed. These are the deepest globular cluster luminosity functions in an elliptical galaxy determined so far. The Kolmogorov-Smirnov statistics show that the difference between the globular cluster luminosity functions of NGC 5128 and the Milky Way is not larger than the difference between the ones of M 31 and the Milky Way. The (U-V)_0_ color histogram shows a bimodal distribution. For 23 globular clusters I obtained K-band images with SOFI at the NTT in La Silla. Their positions in the (U-V) vs. (V-K) color-color diagram indicate that they are indeed old globular clusters. Assuming that the globular clusters in NGC 5128 span a similar age range as the ones in the Milky Way and adopting a linear fit between the metallicity and (U-V)0 color, the metal-rich clusters peak at [Fe/H]=-0.6dex and the metal-poor ones peak at [Fe/H]=-1.7dex.
- ID:
- ivo://CDS.VizieR/J/AJ/162/47
- Title:
- UV luminosity in ~25000 2<z<9 galaxies
- Short Name:
- J/AJ/162/47
- Date:
- 16 Mar 2022 00:17:16
- Publisher:
- CDS
- Description:
- Here we provide the most comprehensive determinations of the rest-frame UV luminosity function (LF) available to date with the Hubble Space Telescope (HST) at z~2-9. Essentially all of the noncluster extragalactic legacy fields are utilized, including the Hubble Ultra Deep Field, the Hubble Frontier Fields parallel fields, and all five CANDELS fields, for a total survey area of 1136arcmin^2^. Our determinations include galaxies at z~2-3 leveraging the deep HDUV, UVUDF, and ERS WFC3/UVIS observations available over an ~150arcmin^2^ area in the GOODS-North and GOODS-South regions. All together, our collective samples include >24000 sources, >2.3x larger than previous selections with HST. We identify 5766, 6332, 7240, 3449, 1066, 601, 246, and 33 sources at z~2, 3, 4, 5, 6, 7, 8, and 9, respectively. Combining our results with an earlier z~10 LF determination by Oesch et al., we quantify the evolution of the UV LF. Our results indicate that there is (1) a smooth flattening of the faint-end slope {alpha} from {alpha}~-2.4 at z~10 to {alpha}~-1.5 at z~2, (2) minimal evolution in the characteristic luminosity M* at z>~2.5, and (3) a monotonic increase in the normalization log_10_\{phi}* from z~10 to 2, which can be well described by a simple second-order polynomial, consistent with an "accelerated" evolution scenario. We find that each of these trends (from z~10 to 2.5 at least) can be readily explained on the basis of the evolution of the halo mass function and a simple constant star formation efficiency model.
- ID:
- ivo://CDS.VizieR/J/ApJS/173/441
- Title:
- UV-Luminous galaxies discovered by GALEX
- Short Name:
- J/ApJS/173/441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the properties of a sample of ultraviolet-luminous galaxies (UVLGs) selected by matching the Galaxy Evolution Explorer (GALEX) All-Sky Imaging and Medium Imaging Surveys with the Sloan Digital Sky Survey third data release. The overlap between these two surveys is roughly 450deg^2^. Of 25362 galaxies (with SDSS spectroscopy) in the range 0.0<z<0.3 detected by GALEX, there are 215 galaxies with L>2x10^10^L{sun} at 1530{AA} (observed wavelength).
- ID:
- ivo://CDS.VizieR/J/ApJ/810/71
- Title:
- UV mag of candidate galaxies at 3~<z~<8.5
- Short Name:
- J/ApJ/810/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a robust measurement and analysis of the rest-frame ultraviolet (UV) luminosity functions at z=4-8. We use deep Hubble Space Telescope imaging over the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey/GOODS fields, the Hubble Ultra Deep Field, and the Hubble Frontier Field deep parallel observations near the Abell 2744 and MACS J0416.1-2403 clusters. The combination of these surveys provides an effective volume of 0.6-1.2x10^6^Mpc^3^ over this epoch, allowing us to perform a robust search for faint (M_UV_=-18) and bright (M_UV_<-21) high-redshift galaxies. We select candidate galaxies using a well-tested photometric redshift technique with careful screening of contaminants, finding a sample of 7446 candidate galaxies at 3.5<z<8.5, with >1000 galaxies at z~6-8. We measure both a stepwise luminosity function for candidate galaxies in our redshift samples, and a Schechter function, using a Markov Chain Monte Carlo analysis to measure robust uncertainties. At the faint end, our UV luminosity functions agree with previous studies, yet we find a higher abundance of UV-bright candidate galaxies at z>=6.
14996. UV Observations of the SMC
- ID:
- ivo://CDS.VizieR/J/AJ/113/1011
- Title:
- UV Observations of the SMC
- Short Name:
- J/AJ/113/1011
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A mosaic of four UIT (Ultraviolet Imaging Telescope) far-UV (FUV) ({lambda}_(eff)_=1620{AA}) images, with derived stellar and H II region photometry, is presented for most of the Bar of the SMC. The UV morphology of the SMC's Bar shows that recent star formation there has left striking features including: (a) four concentrations of UV-bright stars spread from northeast to southwest at nearly equal (~30arcmin=0.5kpc) spacings; (b) one of the concentrations, near DEM 55, comprises a well-defined 8-arcmin diameter ring surrounded by a larger H{alpha} ring, suggestive of sequential star formation. FUV PSF photometry is obtained for 11,306 stars in the FUV images, resulting in magnitudes m(162). We present a FUV luminosity function for the SMC Bar, complete to m(162)~14.5. Detected objects are well correlated with other SMC Population I material; of 711 H{alpha} emission-line stars and small nebulae within the UIT fields of view, 520 are identified with FUV sources. The FUV photometry is compared with available ground-based catalogs of supergiants, yielding 191 detections of 195 supergiants with spectral type earlier than F0 in the UIT fields. The (m(162)-V) color for supergiants is a sensitive measure of spectral type. The bluest observed colors for each type agree well with colors computed from unreddened Galactic spectral atlas stars for types earlier than about A0; for later spectral types the observed SMC stars range significantly bluer, as predicted by comparison of low-metallicity and Galactic-composition models. Redder colors for some stars of all spectral types are attributed to the strong FUV extinction arising from even small amounts of SMC dust. Internal SMC reddenings are determined for all catalog stars. All stars with E(B-V)>0.15 are within regions of visible H{alpha} emission. FUV photometry for 42 H{alpha} -selected H II regions in the SMC Bar is obtained for stars and for total emission (as measured in H II-region-sized apertures). The flux-weighted average ratio of total to stellar FUV flux is 2.15; consideration of the stellar FUV luminosity function indicates that most of the excess total flux is due to scattered FUV radiation, rather than stars fainter than m(162)=14.5. Both stellar and total emission are well correlated with H{alpha} fluxes measured by Kennicutt and Hodge (1986ApJ...306..130K), yielding FUV/H{alpha} flux ratios that are consistent with models of SMC metallicity, ages from 1-5Myr, and moderate (E(B-V)=0.0-0.1mag) internal SMC extinction. (Copyright) 1997 American Astronomical Society.
- ID:
- ivo://CDS.VizieR/J/A+A/581/A125
- Title:
- UV/Optical/NIR spectroscopy GRB hosts
- Short Name:
- J/A+A/581/A125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present data and initial results from VLT/X-shooter emission-line spectroscopy of 96 galaxies selected by long gamma-ray bursts (GRBs) at 0.1<z<3.6, the largest sample of GRB host spectra available to date. Most of our GRBs were detected by Swift and 76% are at 0.5<z<2.5 with a median z_med_~1.6.
- ID:
- ivo://CDS.VizieR/J/AJ/141/205
- Title:
- UVOT imaging of M81 and Holmberg IX
- Short Name:
- J/AJ/141/205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Swift UV/Optical Telescope (UVOT) imaging of the galaxies M81 and Holmberg IX. We combine UVOT imaging in three near-ultraviolet (NUV) filters (uvw2: 1928{AA}; uvm2: 2246{AA}; uvw1: 2600{AA}) with ground-based optical imaging from the Sloan Digital Sky Survey to constrain the stellar populations of both galaxies. Our analysis consists of three different methods. First, we use the NUV imaging to identify UV star-forming knots and then perform spectral energy distribution (SED) modeling on the UV/optical photometry of these sources. Second, we measure surface brightness profiles of the disk of M81 in the NUV and optical. Lastly, we use SED fitting of individual pixels to map the properties of the two galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/137/4517
- Title:
- UVOT light curves of supernovae
- Short Name:
- J/AJ/137/4517
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ultraviolet (UV) observations of supernovae (SNe) obtained with the UltraViolet/Optical Telescope (UVOT) on board the Swift spacecraft. This is the largest sample of UV light curves from any single instrument and covers all major SN types and most subtypes.
- ID:
- ivo://CDS.VizieR/J/ApJ/787/29
- Title:
- UVOT photometry of Super-Chandrasekhar mass SNe Ia
- Short Name:
- J/ApJ/787/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Among Type Ia supernovae (SNe Ia), a class of overluminous objects exist whose ejecta mass is inferred to be larger than the canonical Chandrasekhar mass. We present and discuss the UV/optical photometric light curves, colors, absolute magnitudes, and spectra of three candidate Super-Chandrasekhar mass SNe - 2009dc, 2011aa, and 2012dn - observed with the Swift Ultraviolet/Optical Telescope. The light curves are at the broad end for SNe Ia, with the light curves of SN 2011aa being among the broadest ever observed. We find all three to have very blue colors which may provide a means of excluding these overluminous SNe from cosmological analysis, though there is some overlap with the bluest of "normal" SNe Ia. All three are overluminous in their UV absolute magnitudes compared to normal and broad SNe Ia, but SNe 2011aa and 2012dn are not optically overluminous compared to normal SNe Ia. The integrated luminosity curves of SNe 2011aa and 2012dn in the UVOT range (1600-6000 {AA}) are only half as bright as SN 2009dc, implying a smaller ^56^Ni yield. While it is not enough to strongly affect the bolometric flux, the early time mid-UV flux makes a significant contribution at early times. The strong spectral features in the mid-UV spectra of SNe 2009dc and 2012dn suggest a higher temperature and lower opacity to be the cause of the UV excess rather than a hot, smooth blackbody from shock interaction. Further work is needed to determine the ejecta and ^56^Ni masses of SNe 2011aa and 2012dn and to fully explain their high UV luminosities.
