- ID:
- ivo://CDS.VizieR/J/A+A/646/A22
- Title:
- SN 2020faa multiphotometry and spectra
- Short Name:
- J/A+A/646/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of SN 2020faa. This Type II supernova displays a luminous lightcurve that started to rebrighten from an initial decline. We investigate this in relation to the famous supernova iPTF14hls, which received a great deal of attention and multiple interpretations in the literature, but whose nature and source of energy still remain unknown. We demonstrate the great similarity between SN 2020faa and iPTF14hls during the first 6 months, and use this comparison to forecast the evolution of SN 2020faa and to reflect on the less well observed early evolution of iPTF14hls. We present and analyse our observational data, consisting mainly of optical lightcurves from the Zwicky Transient Facility in the gri bands and of a sequence of optical spectra. We construct colour curves and a bolometric lightcurve, and we compare ejecta-velocity and black-body radius evolutions for the two supernovae and for more typical Type II supernovae. The lightcurves show a great similarity with those of iPTF14hls over the first 6 months in luminosity, timescale, and colour. In addition, the spectral evolution of SN 2020faa is that of a Type II supernova, although it probes earlier epochs than those available for iPTF14hls. The similar lightcurve behaviour is suggestive of SN 2020faa being a new iPTF14hls. We present these observations now to advocate follow-up observations, since most of the more striking evolution of supernova iPTF14hls came later, with lightcurve undulations and a spectacular longevity. On the other hand, for SN 2020faa we have better constraints on the explosion epoch than we had for iPTF14hls, and we have been able to spectroscopically monitor it from earlier phases than was done for the more famous sibling.
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- ID:
- ivo://CDS.VizieR/J/A+A/614/A71
- Title:
- SNF20080514-002 and LSQ12fxd spectra
- Short Name:
- J/A+A/614/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of Type Ia supernovae (SNe Ia) can be used to derive accurate cosmological distances through empirical standardization techniques. Despite this success neither the progenitors of SNe Ia nor the explosion process are fully understood. The U-band region has been less well observed for nearby SNe, due to technical challenges, but is the most readily accessible band for high-redshift SNe. Using spectrophotometry from the Nearby Supernova Factory, we study the origin and extent of U-band spectroscopic variations in SNe Ia and explore consequences for their standardization and the potential for providing new insights into the explosion process. We divide the U-band spectrum into four wavelength regions {lambda}(uNi), {lambda}(uTi), {lambda}(uSi) and {lambda}(uCa). Two of these span the Ca H&K {lambda}{lambda}3934,3969 complex. We employ spectral synthesis using SYNAPPS to associate the two bluer regions with Ni/Co and Ti. Results: (1) The flux of the uTi feature is an extremely sensitive temperature/luminosity indicator, standardizing the SN peak luminosity to 0.116+/-0.011mag RMS. A traditional SALT2.4 fit on the same sample yields a 0.135mag RMS. Standardization using uTi also reduces the difference in corrected magnitude between SNe originating from different host galaxy environments. (2) Early U-band spectra can be used to probe the Ni+Co distribution in the ejecta, thus offering a rare window into the source of lightcurve power. (3) The uCa flux further improves standardization, yielding a 0.086+/-0.010mag RMS without the need to include an additional intrinsic dispersion to reach chi^2^/dof~1. This reduction in RMS is partially driven by an improved standardization of Shallow Silicon and 91T-like SNe.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A76
- Title:
- SN2016hnk photometry and spectroscopy
- Short Name:
- J/A+A/630/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive dataset of optical and near-infrared photometry and spectroscopy of type Ia supernova (SN) 2016hnk, combined with integral field spectroscopy (IFS) of its host galaxy, MCG -01-06-070, and nearby environment. Our goal with this complete dataset is to understand the nature of this peculiar object. Methods: Properties of the SN local environment are characterized by means of single stellar population synthesis applied to IFS observations taken two years after the SN exploded. We performed detailed analyses of SN photometric data by studying its peculiar light and color curves. SN 2016hnk spectra were compared to other 1991bg-like SNe Ia, 2002es-like SNe Ia, and Ca-rich transients. In addition, we used abundance stratification modeling to identify the various spectral features in the early phase spectral sequence and also compared the dataset to a modified non-LTE model previously produced for the subluminous SN1999by. Results: SN 2016hnk is consistent with being a subluminous (MB=-16.7mag, sBV=0.43+/-0.03), highly reddened object. The IFS of its host galaxy reveals both a significant amount of dust at the SN location, residual star formation, and a high proportion of old stellar populations in the local environment compared to other locations in the galaxy, which favors an old progenitor for SN 2016hnk. Inspection of a nebular spectrum obtained one year after maximum contains two narrow emission lines attributed to the forbidden [CaII] {lambda}{lambda}7291,7324 doublet with a Doppler shift of 700km/s. Based on various observational diagnostics, we argue that the progenitor of SN 2016hnk was likely a near Chandrasekhar-mass (MCh) carbon-oxygen white dwarf that produced 0.108M_{sun}_ of 56 Ni. Our modeling suggests that the narrow [CaII] features observed in the nebular spectrum are associated with 48 Ca from electron capture during the explosion, which is expected to occur only in white dwarfs that explode near or at the MCh limit.
- ID:
- ivo://CDS.VizieR/J/A+A/573/A12
- Title:
- SN1993J spectra 100 to 500 days post-explosion
- Short Name:
- J/A+A/573/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate line formation processes in Type IIb supernovae (SNe) from 100 to 500 days post-explosion using spectral synthesis calculations. The modelling identifies the nuclear burning layers and physical mechanisms that produce the major emission lines, and the diagnostic potential of these. We compare the model calculations with data on the three best observed Type IIb SNe to-date - SN 1993J, SN 2008ax, and SN 2011dh.
- ID:
- ivo://CDS.VizieR/J/ApJS/175/116
- Title:
- SNU bright quasar survey (SNUQSO)
- Short Name:
- J/ApJS/175/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the first phase of the Seoul National University Bright Quasar Survey in Optical (SNUQSO) as well as its basic observational setup. Previous and current large-area surveys have been successful in identifying many quasars, but they could have missed bright quasars due to their survey design. In order to help complete the census of bright quasars, we have performed spectroscopic observations of new bright quasar candidates selected from various methods based on optical colors, near-infrared colors, radio, and X-ray data. In 2005/2006, we observed 55 bright quasar candidates using the Bohyunsan Optical Echelle Spectrograph (BOES) on the 1.8m telescope at the Bohyunsan Optical Astronomy Observatory in Korea. We identify 14 quasars/Seyferts from our observation, including an optically bright quasar with i=14.98mag at z=0.092 (SDSS J003236.59-091026.2). Non-quasar/Seyfert objects are found to be mostly stars, among which there are five M-type stars and one cataclysmic variable. Our result shows that there still exist bright quasars to be discovered. However, at the same time, we conclude that finding new bright quasars in high Galactic latitude regions is very challenging and that the existing compilation of optically bright quasars is nearly complete in the northern hemisphere.
2336. SN 2012Z spectra
- ID:
- ivo://CDS.VizieR/J/A+A/573/A2
- Title:
- SN 2012Z spectra
- Short Name:
- J/A+A/573/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 8 unpublished low-resolution visual-wavelength spectra of the Type Iax supernova 2012Z ranging from +1.8d to +248.1d relative to B-band maximum. In addition a high-resolution spectrum is presented obtained on -6.4d. Accompanying these data are 7 low-resolution spectra ranging from -9.2d to +33.8d, which were previously published by Foley et al. (2013ApJ...767...57F). The Foley et al. spectra were provided in normalized ascii format, which we have convert to fits format. Finally, we present the most comprehensive set of near-infrared spectra yet obtained for a Type Ia supernova. This includes 10 epochs ranging from -7.3d to +268.8d relative to B-band maximum. For spectra taken with ESO facilities a single fits file is present for each instrumental setup, i.e., each grating has its own fits file. For the FIRE spectra the one-dimensional spectra are stored in fits files as 2048x3 arrays, corresponding to the wavelength, flux and error values for each of the 2048 pixels across the detector. The wavelength and flux are as observed.
- ID:
- ivo://CDS.VizieR/J/ApJ/894/19
- Title:
- SOAR spectra of the WD EPIC 228939929
- Short Name:
- J/ApJ/894/19
- Date:
- 03 Dec 2021 00:38:57
- Publisher:
- CDS
- Description:
- We report the discovery of short-period photometric variability and modulated Zeeman-split hydrogen emission in SDSSJ125230.93-023417.72 (EPIC 228939929), a variable white dwarf star observed at long cadence in K2 Campaign 10. The behavior is associated with a magnetic (B=5.0MG) spot on the stellar surface, making the 317.278s period a direct measurement of the stellar rotation rate. This object is therefore the fastest-rotating, apparently isolated (without a stellar companion) white dwarf yet discovered and the second found to exhibit chromospheric Balmer emission after GD 356, in which the emission has been attributed to a unipolar inductor mechanism driven by a possible rocky planet. We explore the properties and behavior of this object, and consider whether its evolution may hold implications for white dwarf mergers and their remnants.
- ID:
- ivo://CDS.VizieR/J/ApJS/217/12
- Title:
- S7 observations with WiFeS of active galaxies
- Short Name:
- J/ApJS/217/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Here we describe the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) and present results on 64 galaxies drawn from the first data release. The S7 uses the Wide Field Spectrograph (WiFeS) mounted on the ANU 2.3m telescope located at the Siding Spring Observatory to deliver an integral field of 38x25 arcsec at a spectral resolution of R=7000 in the red (530-710nm), and R=3000 in the blue (340-560nm). From these data cubes we have extracted the narrow-line region spectra from a 4 arcsec aperture centered on the nucleus. We also determine the H{beta} and [OIII]{lambda}5007 fluxes in the narrow lines, the nuclear reddening, the reddening-corrected relative intensities of the observed emission lines, and the H{beta} and [OIII]{lambda}5007 luminosities determined from spectra for which the stellar continuum has been removed. We present a set of images of the galaxies in [OIII]{lambda}5007, [NII]{lambda}6584, and H{alpha}, which serve to delineate the spatial extent of the extended narrow-line region and also to reveal the structure and morphology of the surrounding HII regions. Finally, we provide a preliminary discussion of those Seyfert 1 and Seyfert 2 galaxies that display coronal emission lines in order to explore the origin of these lines.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A135
- Title:
- Sodium detection in WASP-69b atmosphere
- Short Name:
- J/A+A/608/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the transmission spectrum around the Na I doublet at 589nm of the extrasolar planet WASP-69b, and compare the analysis to that of the well-know hot Jupiter HD 189733b. We also present the analysis of the Rossiter-McLaughlin (RM) effect for WASP-69b. We observed two transits of WASP-69b with the HARPS-North spectrograph (R=115 000) at the TNG telescope. We perform a telluric contamination subtraction based on the comparison between the observed spectra and a telluric water model. Then, the common steps of the differential spectroscopy are followed to extract the transmission spectrum. The method is tested with archival transit data of the extensively studied exoplanet HD 189733b, obtained with the HARPS-South spectrograph at ESO 3.6m telescope, and then applied to WASP-69b data. For HD 189733b, we spectrally resolve the NaI doublet and measure line contrasts of 0.72+/-0.05% (D2) and 0.51+/-0.05% (D1), and FWHMs of 0.64+/-0.04{AA} (D2) and 0.60+/-0.06{AA} (D1), in agreement with previously published results. For WASP-69b only the contrast of the D2 line can be measured (5.8+/-0.3%). This corresponds to a detection at the 5sigma-level of excess absorption of 0.5+/-0.1% in a passband of 1.5{AA}. By measuring the RM effect, we get an angular rotation of 0.24^+0.02^_-0.01_rad/day and a sky-projected angle between the stellar rotation axis and the normal of orbit plane of 0.4^+2.0^_-1.9_{deg} FOR wasP-69b. Similar results to those previously presented in the literature are obtained for the RM analysis of HD 189733b.
- ID:
- ivo://CDS.VizieR/J/ApJS/208/7
- Title:
- Sodium excess objects. I. SDSS-DR7
- Short Name:
- J/ApJS/208/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several studies have reported the presence of sodium excess objects having neutral atomic absorption lines at 5895{AA} (Na.D) and 8190{AA} that are deeper than expected based on stellar population models that match the stellar continuum. The origin of these lines is therefore hotly debated. van Dokkum & Conroy (2010Natur.468..940V) proposed that low-mass stars (<~0.3M_{sun}_) are more prevalent in massive early-type galaxies, which may lead to a strong Na I 8190 line strength. It is necessary to test this prediction, however, against other prominent optical line indices such as Na.D, Mg b, and Fe 5270, which can be measured with a significantly higher signal-to-noise ratio than Na I 8190. We identified a new sample of roughly 1000 Na.D excess objects (NEOs; ~8% of galaxies in the sample) based on Na.D line strength in the redshift range 0.00<=z<=0.08 from the Sloan Digital Sky Survey (SDSS) DR7 through detailed analysis of galaxy spectra. We explore the properties of these new objects here. The novelty of this work is that the galaxies were carefully identified through direct visual inspection of SDSS images, and we systematically compared the properties of NEOs and those of a control sample of galaxies with normal Na.D line strengths. We note that the majority of galaxies with high velocity dispersions ({sigma}_e_>250km/s) show Na.D excesses.
