- ID:
- ivo://CDS.VizieR/J/ApJ/889/44
- Title:
- UKIRT obs. of red supergiants in M31
- Short Name:
- J/ApJ/889/44
- Date:
- 17 Jan 2022 11:49:04
- Publisher:
- CDS
- Description:
- The mass-loss rates of red supergiant stars (RSGs) are poorly constrained by direct measurements, and yet the subsequent evolution of these stars depends critically on how much mass is lost during the RSG phase. In 2012 the Geneva evolutionary group updated their mass-loss prescription for RSGs with the result that a 20M_{sun}_ star now loses 10 times more mass during the RSG phase than in the older models. Thus, higher-mass RSGs evolve back through a second yellow supergiant phase rather than exploding as Type II-P supernovae, in accord with recent observations (the so-called "RSG Problem"). Still, even much larger mass-loss rates during the RSG phase cannot be ruled out by direct measurements of their current dust-production rates, as such mass loss is episodic. Here, we test the models by deriving a luminosity function for RSGs in the nearby spiral galaxy, M31, which is sensitive to the total mass loss during the RSG phase. We carefully separate RSGs from asymptotic giant branch stars in the color-magnitude diagram following the recent method exploited by Yang+ (2019, J/A+A/629/A91) in their Small Magellanic Cloud studies. Comparing our resulting luminosity function with that predicted by the evolutionary models shows that the new prescription for RSG mass loss does an excellent job of matching the observations, and we can readily rule out significantly larger values.
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- ID:
- ivo://CDS.VizieR/J/A+A/598/A1
- Title:
- [U]LIRGs - on the trail of AGN's types
- Short Name:
- J/A+A/598/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this work is to characterize physical properties of Ultra Luminous Infrared Galaxies (ULIRGs) and Luminous Infrared Galaxies (LIRGs) detected in the far-infrared (FIR) 90um band in the AKARI Deep Field-South (ADF-S) survey. In particular, we want to estimate the active galactic nucleus (AGN) contribution to the LIRGs and ULIRGs' infrared emission and which types of AGNs are related to their activity. We examined 69 galaxies at redshift >=0.05 detected at 90um by the AKARI satellite in the AKARI Deep-Field South (ADF-S), with optical counterparts and spectral coverage from the ultraviolet to the FIR. We used two independent spectral energy distribution fitting codes: one fitting the SED from FIR to FUV (CIGALE) (we use the results from CIGALE as a reference) and gray-body + power spectrum fit for the infrared part of the spectra (CMCIRSED) in order to identify a subsample of ULIRGs and LIRGs, and to estimate their properties. A final catalog of 39 LIRGs and ULIRGs is used for our analysis.
- ID:
- ivo://CDS.VizieR/J/AJ/141/163
- Title:
- Ultimate light curve of SN 1998bw/GRB 980425
- Short Name:
- J/AJ/141/163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multicolor light curves of SN 1998bw which appeared in ESO184-G82 in close temporal and spatial association with GRB 980425. The light curves are based on observations conducted at Cerro Tololo Inter-American Observatory (CTIO) and data from the literature. The CTIO photometry reaches ~86-days after the gamma-ray burst (GRB) in U and ~160-days after the GRB in BV(RI)C. The observations in U extend the previously known coverage by about 30-days and determine the slope of the early exponential tail. We calibrate a large set of local standards in common with those of previous studies and use them to transform published observations of the supernova (SN) to our realization of the standard photometric system.
- ID:
- ivo://CDS.VizieR/J/MNRAS/427/3280
- Title:
- Ultra-cool dwarfs at low Galactic latitudes
- Short Name:
- J/MNRAS/427/3280
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an ultra-cool dwarf (UCD) catalogue compiled from low southern Galactic latitudes and mid-plane, from a cross-correlation of the Two Micron All-Sky Survey (2MASS) and the SuperCOSMOS survey. The catalogue contains 246 members identified from 5042deg^2^ within 220{deg}<=l<=360{deg} and 0{deg}<l<=30{deg}, for |b|<=15{deg}. Sixteen candidates are spectroscopically confirmed in the near-infrared as UCDs with spectral types from M7.5V to L9, the latest being the unusual blue L dwarf 2MASSJ11263991-5003550. Our catalogue selection method is presented enabling UCDs from ~M8V to the L-T transition to be selected down to a 2MASS limiting magnitude of Ks=~14.5mag (for S/N>=10).
- ID:
- ivo://CDS.VizieR/J/AJ/136/1290
- Title:
- Ultracool dwarfs from the 2MASS
- Short Name:
- J/AJ/136/1290
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using data from the 2 Micron All Sky Survey All-Sky Point Source Catalogue, we have extended our census of nearby ultracool dwarfs to cover the full celestial sphere above Galactic latitude of 15{deg}. Starting with an initial catalog of 2139484 sources, we have winnowed the sample to 467 candidate late-type M or L dwarfs within 20pc of the Sun. Fifty-four of those sources already have spectroscopic observations confirming them as late-type dwarfs. We present optical spectroscopy of 376 of the remaining 413 sources, and identify 44 as ultracool dwarfs with spectroscopic distances less than 20pc. Twenty-five of the 37 sources that lack optical data have near-infrared spectroscopy. Combining the present sample with our previous results and data from the literature, we catalog 94 L dwarf systems within 2pc. We discuss the distribution of activity, as measured by H{alpha} emission, in this volume-limited sample. We have coupled the present ultracool catalog with data for stars in the northern 8pc sample and recent (incomplete) statistics for T dwarfs to provide a snapshot of the current 20pc census as a function of spectral type.
- ID:
- ivo://CDS.VizieR/J/AJ/160/19
- Title:
- 827 ultracool dwarfs with K2
- Short Name:
- J/AJ/160/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The occurrence of planets orbiting ultracool dwarfs is poorly constrained. We present results from a guest observer program on NASA's K2 spacecraft to search for transiting planets orbiting a sample of 827 ultracool dwarfs. Having found no transiting planets in our sample, we determined an upper limit on the occurrence of planets. We simulated planets orbiting our sample for a range of orbital periods and sizes. For the simulated planets that transit their host, we injected the transit light curve into the real K2 light curves, then attempted to recover the injected planets. For a given occurrence rate, we calculated the probability of seeing no planets, and use the results to place an upper limit on planet occurrence as a function of planet radius and orbital period. We find that short-period, mini-Neptune and Jupiter-sized planets are rare around ultracool dwarfs, consistent with results for early and mid-type M dwarf stars. We constrain the occurrence rate {eta} for planets between 0.5 and 10 R{earth} with orbital periods between 1 and 26.3days.
3297. Ultracool white dwarfs
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/3966
- Title:
- Ultracool white dwarfs
- Short Name:
- J/MNRAS/449/3966
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present parallax observations and a detailed model atmosphere analysis of 54 cool and ultracool (Teff<4000K) white dwarfs (WDs) in the solar neighbourhood. For the first time, a large number of cool and ultracool WDs have distance and tangential velocities measurements available. Our targets have distances ranging from 21pc to >100pc, and include five stars within 30pc. Contrary to expectations, all but two of them have tangential velocities smaller than 150km/s thus suggesting Galactic disc membership. The oldest WDs in this sample have WD cooling ages of 10Gyr, providing a firm lower limit to the age of the thick disc population. Many of our targets have uncharacteristically large radii, indicating that they are low-mass WDs. It appears that we have detected the brighter population of cool and ultracool WDs near the Sun. The fainter population of ultracool CO-core WDs remain to be discovered in large numbers. The Large Synoptic Survey Telescope should find these elusive, more massive ultracool WDs in the solar neighbourhood.
- ID:
- ivo://CDS.VizieR/J/ApJS/187/251
- Title:
- Ultradeep Ks imaging in the GOODS-N
- Short Name:
- J/ApJS/187/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an ultradeep K_s_-band image that covers 0.5x0.5deg^2^ centered on the Great Observatories Origins Deep Survey-North (GOODS-N). The image reaches a 5{sigma} depth of K_s,AB_=24.45 in the GOODS-N region, which is as deep as the GOODS-N Spitzer Infrared Array Camera (IRAC) 3.6um image. We present a new method of constructing IRAC catalogs that uses the higher spatial resolution K_s_ image and catalog as priors and iteratively subtracts fluxes from the IRAC images to estimate the IRAC fluxes. Our iterative method is different from the {chi}^2^ approach adopted by other groups. We verified our results using data taken in two different epochs of observations, as well as by comparing our colors with the colors of stars and with the colors derived from model spectral energy distributions of galaxies at various redshifts. We make available to the community our WIRCam K_s_-band image and catalog (94951 objects in 0.25deg^2^), the Interactive Data Language pipeline used for reducing the WIRCam images, and our IRAC 3.6-8.0um catalog (16950 objects in 0.06deg^2^ at 3.6um). With this improved K_s_ and IRAC catalog and a large spectroscopic sample from our previous work (Cat. <J/ApJ/689/687>), we study the color-magnitude and color-color diagrams of galaxies. We compare the effectiveness of using K_s_ and IRAC colors to select active galactic nuclei and galaxies at various redshifts. We also study a color selection of z=0.65-1.2 galaxies using the K_s_, 3.6um, and 4.5um bands.
- ID:
- ivo://CDS.VizieR/J/A+A/436/457
- Title:
- Ultra-steep spectrum radio sources
- Short Name:
- J/A+A/436/457
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of radio (VLA) and optical (ESO/La Silla) imaging of a sample of 52 radio sources having an ultra-steep radio spectrum with {alpha} mostly steeper than -1.1 at decimetre wavelengths (median {alpha}=-1.22). Radio-optical overlays are presented to an astrometric accuracy of ~1". For 41 of the sources, radio spectral indices are newly determined using unpublished observations made with the 100-m Effelsberg radio telescope. For 14 of the sources identified with relatively brighter optical counterparts, spectroscopic observations were also carried out at La Silla and their redshifts are found to lie in the range 0.4 to 2.6.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A156
- Title:
- UltraVISTA Catalogue Release DR1
- Short Name:
- J/A+A/544/A156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we describe the first data release of the UltraVISTA near-infrared imaging survey of the COSMOS field. We summarise the key goals and design of the survey and provide a detailed description of our data reduction techniques. We provide stacked, sky-subtracted images in Y JHKs and narrow-band filters constructed from data collected during the first year of UltraVISTA observations.
