- ID:
- ivo://CDS.VizieR/J/ApJ/893/143
- Title:
- UBVRIJHK & spec. obs. of type Ia SN2019ein
- Short Name:
- J/ApJ/893/143
- Date:
- 07 Mar 2022 07:30:20
- Publisher:
- CDS
- Description:
- We present optical observations of the Type Ia supernova (SN) 2019ein, starting two days after the estimated explosion date. The spectra and light curves show that SN 2019ein belongs to a high-velocity (HV) and broad-line group with a relatively rapid decline in the light curves ({Delta}m_15_(B)=1.36+/-0.02mag) and a short rise time (15.37+/-0.55days). The SiII{lambda}6355 velocity, associated with a photospheric component but not with a detached high-velocity feature, reached ~20000km/s 12 days before the B-band maximum. The line velocity, however, decreased very rapidly and smoothly toward maximum light, to ~13000km/s, which is relatively low among HV SNe. This indicates that the speed of the spectral evolution of HV SNe Ia is correlated with not only the velocity at maximum light, but also the light-curve decline rate, as is the case for normal-velocity (NV) SNeIa. Spectral synthesis modeling shows that the outermost layer at >17000km/s is well described by an O-Ne-C burning layer extending to at least 25000km/s, and there is no unburnt carbon below 30000km/s; these properties are largely consistent with the delayed detonation scenario and are shared with the prototypical HV SN 2002bo despite the large difference in {Delta}m_15_(B). This structure is strikingly different from that derived for the well-studied NV SN 2011fe. We suggest that the relation between the mass of ^56^Ni (or {Delta}m_15_) and the extent of the O-Ne-C burning layer provides an important constraint on the explosion mechanism(s) of HV and NV SNe.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/604/A48
- Title:
- UBVRI photometry and line fluxes of AG Peg
- Short Name:
- J/A+A/604/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AG Peg is known as the slowest symbiotic nova, which experienced its nova-like outburst around 1850. After 165 years, during June of 2015, it erupted again showing characteristics of the Z And-type outburst. The primary objective is to determine basic characteristics, the nature and type of the 2015 outburst of AG Peg. We achieved this aim by modelling the spectral energy distribution using low-resolution spectroscopy (330-750nm), medium-resolution spectroscopy (420-720nm; R=11000), and UBVR_C_I_C_ photometry covering the 2015 outburst with a high cadence. Optical observations were complemented with the archival HST and FUSE spectra from the preceding quiescence. During the outburst, the luminosity of the hot component was in the range of 2-11x10^37^(d/0.8kpc})^2^erg/s. To generate the maximum luminosity the white dwarf (WD) had to accrete at ~3x10^-7^M_{sun}/yr, which exceeds the stable-burning limit and thus led to blowing optically thick wind from the WD. We determined its mass-loss rate to a few x10^-6^M_{sun}/yr. At the high temperature of the ionising source, 1.5-2.3x10^5^K, the wind converted a fraction of the WD's photospheric radiation into the nebular emission that dominated the optical. A one order of magnitude increase of the emission measure, from a few x10^59^(d/0.8kpc)^2^/cm^3^ during quiescence, to a few x10^60^(d/0.8kpc)^2^/cm^3^ during the outburst, caused a 2mag brightening in the LC, which is classified as the Z And-type of the outburst. The very high nebular emission and the presence of a disk-like HI region encompassing the WD, as indicated by a significant broadening and high flux of the Raman-scattered OVI 6825{AA} line during the outburst, is consistent with the ionisation structure of hot components in symbiotic stars during active phases.
- ID:
- ivo://CDS.VizieR/J/A+A/367/199
- Title:
- UBVR photometry of AX Per
- Short Name:
- J/A+A/367/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 2 presents standard broad band U, B, V, R photoelectric photometry of AX Persei. Each value represents the average of the observations during a night. The uncertainty of these night-means is of a few x 0.001mag in the B, V and R bands, and up to 0.02mag in the U band. Table 3 presents observed spectrophotometric parameters of the spectrum: the line fluxes, fluxes in the local continuum and the radial velocities.
- ID:
- ivo://CDS.VizieR/J/PAZh/28/764
- Title:
- UBVR photometry of Nova Mon 2002 (V838 Mon)
- Short Name:
- J/PAZh/28/764
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVR photometric and spectroscopic observations of V838 Mon during the outbursts.
- 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/ApJS/171/29
- Title:
- UCSD/Keck Damped Ly{alpha} Abundance Database
- Short Name:
- J/ApJS/171/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We publish the Keck/HIRES and Keck/ESI spectra that we have obtained during the first 10 years of Keck observatory operations. Our full sample includes 42 HIRES spectra and 39 ESI spectra along 65 unique sight lines providing abundance measurements on about 85 DLA systems. The normalized data can be downloaded from the journal or from our supporting Web site. The database includes all of the sight lines that have been included in our papers on the chemical abundances, kinematics, and metallicities of the damped Ly{alpha} systems. This data has also been used to argue for variations in the fine-structure constant. We present new chemical abundance measurements for 10 damped Ly{alpha} systems and a summary table of high-resolution metallicity measurements (including values from the literature) for 153 damped Ly{alpha} systems at z>1.6. We caution, however, that this metallicity sample (and all previous ones) is biased to higher N_HI_ values than a random sample.
2907. U Gem spectroscopy
- ID:
- ivo://CDS.VizieR/J/MNRAS/361/1091
- Title:
- U Gem spectroscopy
- Short Name:
- J/MNRAS/361/1091
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a phase-resolved spectroscopic study of the secondary star in the cataclysmic variable (CV) U Gem. We use our data to measure the radial velocity semi-amplitude, systemic velocity and rotational velocity of the secondary star. Combining this with literature data allows us to determine masses and radii for both the secondary star and white dwarf, which are independent of any assumptions about their structure. We use these to compare their properties to those of field stars and find that both components follow field mass-radius relationships. The secondary star has the mass, radius, luminosity and photometric temperature of an M2 star, but a spectroscopic temperature of M4. The latter may well be due to a high metallicity. There is a troubling inconsistency between the radius of the white dwarf inferred from its gravitational redshift and inclination and that inferred from its temperature, flux and astrometric distance.
- 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.
