- 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.
Number of results to display per page
Search Results
- 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/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.
- ID:
- ivo://CDS.VizieR/J/A+A/523/A64
- Title:
- UV properties of starbursts
- Short Name:
- J/A+A/523/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have computed evolutionary synthesis models covering metallicities from PopIII to solar, a wide range of IMFs, and two star-formation histories (bursts and constant star-formation). The detailed predictions these models, including their time dependence, are given here. The predicted quantities include ionising fluxes, UV continuum properties, recombination line strengths (for Ly{alpha}, HeII and other lines), as well as several other quantities of interest. The models provided here cover a wider range of parameter space than our earlier calculations (Schaerer, 2003A&A...397..527S, Cat. VI/109).
- ID:
- ivo://CDS.VizieR/J/MNRAS/300/303
- Title:
- UV-selected galaxy redshift survey
- Short Name:
- J/MNRAS/300/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The table contains the first results of a spectroscopic survey of galaxies constructed from a flux-limited sample of stars, galaxies and QSOs imaged at 2000{AA} with the FOCA balloon-borne imaging camera (see Milliard et al., 1992A&A...257...24M) The galaxies were selected in the rest frame ultraviolet (UV), in Selected Area 57. Accurate positions for the UV sources have been obtained by matching with optical counterparts using APM scans of the Palomar Sky Survey limited at B=20.5. The results presented here are derived from optical spectroscopy conducted with the WIYN telescope and the WHT for 142 faint sources. The redshift distribution for this UV- selected sample extends over 0<z<0.5, and a high fraction of the sources show intense nebular emission lines and UV-optical colours bluer than normal Hubble sequence galaxies. Updated results for these galaxies were published later (see Sullivan et al. 2000, Cat. <J/MNRAS/312/442>)
- ID:
- ivo://CDS.VizieR/J/MNRAS/312/442
- Title:
- UV-selected galaxy redshift survey. II.
- Short Name:
- J/MNRAS/312/442
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present further spectroscopic observations for a sample of galaxies selected in the vacuum ultraviolet (UV) at 2000{AA} from the FOCA balloon-borne imaging camera of Milliard et al. (1992A&A...257...24M). This work represents an extension of the initial study by Treyer et al. (Cat. <J/MNRAS/300/303>). Our enlarged catalogue contains 433 sources (~3 times as many as in our earlier study) across two FOCA fields. 273 of these are galaxies, nearly all with redshifts z~0-0.4. Nebular emission-line measurements are available for 216 galaxies, allowing us to address issues of excitation, reddening and metallicity. The UV and H{alpha} luminosity functions strengthen our earlier assertions that the local volume-averaged star formation rate is higher than indicated from earlier surveys. Moreover, internally within our sample, we do not find a steep rise in the UV luminosity density with redshift over 0<z<0.4. Our data are more consistent with a modest evolutionary trend, as suggested by recent redshift survey results. Investigating the emission-line properties, we find no evidence for a significant number of AGN in our sample; most UV-selected sources to z~0.4 are intense star-forming galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/784/127
- Title:
- UV spectra of classical T Tauri stars
- Short Name:
- J/ApJ/784/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The far-ultraviolet (FUV; 912-1700 {AA}) radiation field from accreting central stars in classical T Tauri systems influences the disk chemistry during the period of giant planet formation. The FUV field may also play a critical role in determining the evolution of the inner disk (r<10 AU), from a gas- and dust-rich primordial disk to a transitional system where the optically thick warm dust distribution has been depleted. Previous efforts to measure the true stellar+accretion-generated FUV luminosity (both hot gas emission lines and continua) have been complicated by a combination of low-sensitivity and/or low-spectral resolution and did not include the contribution from the bright Ly{alpha} emission line. In this work, we present a high-resolution spectroscopic study of the FUV radiation fields of 16 T Tauri stars whose dust disks display a range of evolutionary states. We include reconstructed Ly{alpha} line profiles and remove atomic and molecular disk emission (from H_2_ and CO fluorescence) to provide robust measurements of both the FUV continuum and hot gas lines (e.g., Ly{alpha}, N V, C IV, He II) for an appreciable sample of T Tauri stars for the first time. We find that the flux of the typical classical T Tauri star FUV radiation field at 1 AU from the central star is ~10^7^ times the average interstellar radiation field. The Ly{alpha} emission line contributes an average of 88% of the total FUV flux, with the FUV continuum accounting for an average of 8%. Both the FUV continuum and Ly{alpha} flux are strongly correlated with C IV flux, suggesting that accretion processes dominate the production of both of these components. On average, only ~0.5% of the total FUV flux is emitted between the Lyman limit (912 {AA}) and the H_2_(0-0) absorption band at 1110 {AA}. The total and component-level high-resolution radiation fields are made publicly available in machine-readable format.
2978. UV spectra of old novae
- ID:
- ivo://CDS.VizieR/J/A+A/560/A49
- Title:
- UV spectra of old novae
- Short Name:
- J/A+A/560/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an overview of the UV spectral properties of old novae as a class. The data and results of this paper, together with data from the outburst phases, will be utilized in a follow-up study to determine statistical properties and to investigate correlations among the physical parameters of the quiescent and eruptive phases.
- ID:
- ivo://CDS.VizieR/J/A+A/470/317
- Title:
- UV spectra of the central star of Sh 2-216
- Short Name:
- J/A+A/470/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a comprehensive spectral analysis of LS V +46 21 in order to compare its photospheric properties to theoretical predictions from stellar evolution theory as well as from diffusion calculations. LS V +46 21 is the DAO-type central star of the planetary nebula Sh 2-216. High-resolution, high-S/N ultraviolet observations obtained with FUSE and STIS aboard the HST as well as the optical spectrum have been analyzed in order to determine the photospheric parameters and the spectroscopic distance. We performed a detailed spectral analysis of the ultraviolet and optical spectrum by means of state-of-the-art NLTE model-atmosphere techniques. From the NIV-NV, OIV-OVI, SiIV-SiV, and FeV-FeVII ionization equilibria, we determined an effective temperature of 95+/-2kK with high precision. The surface gravity is logg=6.9+/-0.2. An unexplained discrepancy appears between the spectroscopic distance d=224^+46^_-58_pc and the parallax distance d=129^+6^_-5_pc of LS V +46 21. For the first time, we have identified Mg IV and Ar VI absorption lines in the spectrum of a hydrogen-rich central star and determined the Mg and Ar abundances as well as the individual abundances of iron-group elements (Cr, Mn, Fe, Co, and Ni). With the realistic treatment of metal opacities up to the iron group in the model-atmosphere calculations, the so-called Balmer-line problem (found in models that neglect metal-line blanketing) vanishes. Spectral analysis by means of NLTE model atmospheres has presently arrived at a high level of sophistication, which is now hampered largely by the lack of reliable atomic data and accurate line-broadening tables. Strong efforts should be made to improve upon this situation.
- ID:
- ivo://CDS.VizieR/J/ApJ/754/69
- Title:
- UV spectroscopy of solar-mass stars
- Short Name:
- J/ApJ/754/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare high-resolution ultraviolet spectra of the Sun and thirteen solar-mass main-sequence stars with different rotational periods that serve as proxies for their different ages and magnetic field structures. In this, the second paper in the series, we study the dependence of ultraviolet emission-line centroid velocities on stellar rotation period, as rotation rates decrease from that of the Pleiades star HII314 (P_rot_=1.47days) to {alpha} Cen A (P_rot_=28days). Our stellar sample of F9 V to G5 V stars consists of six stars observed with the Cosmic Origins Spectrograph on the Hubble Space Telescope (HST) and eight stars observed with the Space Telescope Imaging Spectrograph on HST. We find a systematic trend of increasing redshift with more rapid rotation (decreasing rotation period) that is similar to the increase in line redshift between quiet and plage regions on the Sun. The fastest-rotating solar-mass star in our study, HII314, shows significantly enhanced redshifts at all temperatures above logT=4.6, including the corona, which is very different from the redshift pattern observed in the more slowly rotating stars. This difference in the redshift pattern suggests that a qualitative change in the magnetic-heating process occurs near P_rot_=2days. We propose that HII314 is an example of a solar-mass star with a magnetic heating rate too large for the physical processes responsible for the redshift pattern to operate in the same way as for the more slowly rotating stars. HII314 may therefore lie above the high activity end of the set of solar-like phenomena that is often called the "solar-stellar connection."
