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- ID:
- ivo://CDS.VizieR/J/ApJ/737/86
- Title:
- UCD galaxies in the Coma cluster
- Short Name:
- J/ApJ/737/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have undertaken a spectroscopic search for ultra-compact dwarf galaxies (UCDs) in the dense core of the dynamically evolved, massive Coma cluster as part of the Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) Coma Cluster Treasury Survey. UCD candidates were initially chosen based on color, magnitude, degree of resolution within the ACS images, and the known properties of Fornax and Virgo UCDs. Follow-up spectroscopy with Keck/Low-Resolution Imaging Spectrometer confirmed 27 candidates as members of the Coma cluster, a success rate >60% for targeted objects brighter than M_R_=-12. Another 14 candidates may also prove to be Coma members, but low signal-to-noise spectra prevent definitive conclusions.
- ID:
- ivo://CDS.VizieR/J/AJ/126/1720
- Title:
- ugriz and H{alpha} of double-peaked AGN
- Short Name:
- J/AJ/126/1720
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new sample of 116 double-peaked Balmer line active galactic nuclei (AGNs) selected from the Sloan Digital Sky Survey.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/693/370
- Title:
- 24um flux-limited sample of galaxies
- Short Name:
- J/ApJ/693/370
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mid-infrared spectroscopic analysis of a flux-limited sample of galaxies with f_{nu}_(24um)>10mJy is presented. Sources observed are taken from the Spitzer First Look Survey (FLS) catalog and from the NOAO Deep Wide-Field Survey region in Bootes (NDWFS). The spectroscopic sample includes 60 of the 100 sources in these combined catalogs having f_{nu}_(24um)>10 mJy. New spectra from the Spitzer Infrared Spectrograph are presented for 25 FLS sources and for 11 Bootes active galactic nuclei (AGNs); these are combined with 24 Bootes starburst galaxies previously published to determine the distribution of mid-infrared spectral characteristics for the total 10mJy sample. Sources have 0.01<z<2.4 and 41.8<log{nu}L_{nu}_(15um)<46.2(ergs/s).
- ID:
- ivo://CDS.VizieR/J/AJ/160/44
- Title:
- Upper Scorpius spectroscopy and photometry
- Short Name:
- J/AJ/160/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have refined the census of stars and brown dwarfs in the Upper Sco association (~10Myr, ~145pc) by (1) updating the selection of candidate members from our previous survey to include the high-precision astrometry from the second data release of Gaia, (2) obtaining spectra of a few hundred candidate members to measure their spectral types and verify their youth, and (3) assessing the membership (largely with Gaia astrometry) of 2020 stars toward Upper Sco that show evidence of youth in this work and previous studies. We arrive at a catalog of 1761 objects that are adopted as members of Upper Sco. The distribution of spectral types among the adopted members is similar to those in other nearby star-forming regions, indicating a similar initial mass function. In previous studies, we have compiled mid-infrared photometry from the Wide-field Infrared Survey Explorer and the Spitzer Space Telescope for members of Upper Sco and used those data to identify the stars that show evidence of circumstellar disks; we present the same analysis for our new catalog of members. As in earlier work, we find that the fraction of members with disks increases with lower stellar masses, ranging from <~10% for >1M{sun} to ~22% for 0.01-0.3M{sun}. Finally, we have estimated the relative ages of Upper Sco and other young associations using their sequences of low-mass stars in M_G_RP__ versus G_BP_-G_RP_. This comparison indicates that Upper Sco is a factor of two younger than the {beta}Pic association (21-24Myr) according to both nonmagnetic and magnetic evolutionary models.
- ID:
- ivo://CDS.VizieR/J/AJ/126/1208
- Title:
- UVBI magnitudes and redshifts in HDF-South
- Short Name:
- J/AJ/126/1208
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 97 (*) spectroscopic redshifts of z<1 galaxies in the Hubble Deep Field South (HDF-S) and its flanking fields (FFs). In the HDF-S proper we observed approximately half the galaxies brighter than I_814_(AB)=24 and obtained redshifts for 76% of them. Targets in our HDF-S sample were preselected to be at z<1 based on photometric redshifts, while in the FFs a simple magnitude cut was used. The photometric redshift preselection in the HDF-S resulted in a spectroscopic success rate that is significantly higher than in the FFs, where no preselection was applied. The rms precision of our redshift measurements, determined from repeat observations, is {delta}z=0.0003. We present the photometry and redshifts for the 97 objects for which we secured spectroscopic redshifts and describe the basic properties of this sample. The photometry was derived from the HST observations; the spectroscopy was obtained at the VLT using the FORS2 spectrograph on the Kueyen (UT2) and Yepun (UT4) 8.2m telescopes. (*) Actually, 103 redshifts in table1.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/147
- Title:
- UV-NIR LCs of the energetic H-stripped SN2016coi
- Short Name:
- J/ApJ/883/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present comprehensive observations and analysis of the energetic H-stripped SN 2016coi (a.k.a. ASASSN-16fp), spanning the {gamma}-ray through optical and radio wavelengths, acquired within the first hours to ~420 days post explosion. Our observational campaign confirms the identification of He in the supernova (SN) ejecta, which we interpret to be caused by a larger mixing of Ni into the outer ejecta layers. By modeling the broad bolometric light curve, we derive a large ejecta-mass-to-kinetic-energy ratio (M_ej_~4-7M_{sun}_, E_k_~(7-8)x10^51^erg). The small [CaII]{lambda}{lambda}7291,7324 to [OI]{lambda}{lambda}6300,6364 ratio (~0.2) observed in our late-time optical spectra is suggestive of a large progenitor core mass at the time of collapse. We find that SN 2016coi is a luminous source of X-rays (L_X_>10^39^erg/s in the first ~100 days post explosion) and radio emission (L_8.5GHz_~7x10^27^erg/s/Hz at peak). These values are in line with those of relativistic SNe (2009bb, 2012ap). However, for SN 2016coi, we infer substantial pre-explosion progenitor mass loss with a rate dM/dt~(1-2)x10^-4^M_{sun}_/yr and a sub-relativistic shock velocity v_sh_~0.15c, which is in stark contrast with relativistic SNe and similar to normal SNe. Finally, we find no evidence for a SN- associated shock breakout {gamma}-ray pulse with energy E_{gamma}_>2x10^46^erg. While we cannot exclude the presence of a companion in a binary system, taken together, our findings are consistent with a massive single-star progenitor that experienced large mass loss in the years leading up to core collapse, but was unable to achieve complete stripping of its outer layers before explosion.
- ID:
- ivo://CDS.VizieR/J/ApJ/898/56
- Title:
- UVOT, ZTF gri LCs and spectra of the SN Ia 2019yvq
- Short Name:
- J/ApJ/898/56
- Date:
- 16 Mar 2022 00:53:53
- Publisher:
- CDS
- Description:
- Early observations of Type Ia supernovae (SNe Ia) provide essential clues for understanding the progenitor system that gave rise to the terminal thermonuclear explosion. We present exquisite observations of SN 2019yvq, the second observed SN Ia, after iPTF 14atg, to display an early flash of emission in the ultraviolet (UV) and optical. Our analysis finds that SN 2019yvq was unusual, even when ignoring the initial flash, in that it was moderately underluminous for an SN Ia (M_g_~-18.5mag at peak) yet featured very high absorption velocities (v~15000km/s for SiII{lambda}6355 at peak). We find that many of the observational features of SN 2019yvq, aside from the flash, can be explained if the explosive yield of radioactive 56Ni is relatively low (we measure M_56Ni_=0.31+/-0.05M_{sun}_) and it and other iron-group elements are concentrated in the innermost layers of the ejecta. To explain both the UV/optical flash and peak properties of SN 2019yvq we consider four different models: interaction between the SN ejecta and a nondegenerate companion, extended clumps of ^56^Ni in the outer ejecta, a double-detonation explosion, and the violent merger of two white dwarfs. Each of these models has shortcomings when compared to the observations; it is clear additional tuning is required to better match SN 2019yvq. In closing, we predict that the nebular spectra of SN 2019yvq will feature either H or He emission, if the ejecta collided with a companion, strong [CaII] emission, if it was a double detonation, or narrow [OI] emission, if it was due to a violent merger.