- ID:
- ivo://CDS.VizieR/J/AJ/160/282
- Title:
- Optical and IR spectroscopy of Europa
- Short Name:
- J/AJ/160/282
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The composition of Europa's trailing hemisphere reflects the combined influences of endogenous geologic resurfacing and exogenous sulfur radiolysis. Using spatially resolved visible-wavelength spectra of Europa obtained with the Hubble Space Telescope, we map multiple spectral features across the trailing hemisphere and compare their geographies with the distributions of large-scale geology, magnetospheric bombardment, and surface color. Based on such comparisons, we interpret some aspects of our spectra as indicative of purely exogenous sulfur radiolysis products and other aspects as indicative of radiolysis products formed from a mixture of endogenous material and magnetospheric sulfur. The spatial distributions of two of the absorptions seen in our spectra-a widespread downturn toward the near-UV and a distinct feature at 530nm-appear consistent with sulfur allotropes previously suggested from ground-based spectrophotometry. However, the geographies of two additional features-an absorption feature at 360nm and the spectral slope at red wavelengths-are more consistent with endogenous material that has been altered by sulfur radiolysis. We suggest irradiated sulfate salts as potential candidates for this material, but we are unable to identify particular species with the available data.
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- ID:
- ivo://CDS.VizieR/J/ApJ/853/62
- Title:
- Optical and NIR spectra and LCs of SN2016ija
- Short Name:
- J/ApJ/853/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our analysis of the Type II supernova DLT16am (SN2016ija). The object was discovered during the ongoing D<40Mpc (DLT40) one-day cadence supernova search at r~20.1mag in the "edge-on" nearby (D=20.0+/-4.0Mpc) galaxy NGC1532. The subsequent prompt and high-cadenced spectroscopic and photometric follow-up revealed a highly extinguished transient, with E(B-V)=1.95+/-0.15mag, consistent with a standard extinction law with R_V_=3.1 and a bright (M_V_=-18.48+/-0.77mag) absolute peak magnitude. A comparison of the photometric features with those of large samples of SNe II reveals a fast rise for the derived luminosity and a relatively short plateau phase, with a slope of S_50V_=0.84+/-0.04mag/50days, consistent with the photometric properties typical of those of fast-declining SNeII. Despite the large uncertainties on the distance and the extinction in the direction of DLT16am, the measured photospheric expansion velocity and the derived absolute V-band magnitude at ~50days after the explosion match the existing luminosity-velocity relation for SNeII.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A9
- Title:
- Optical and NIR spectra of SN iPTF13ebh
- Short Name:
- J/A+A/578/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared (NIR) time-series spectroscopy, as well as complementary ultraviolet (UV), optical, and NIR data, of the Type Ia supernova (SN Ia) iPTF13ebh, which was discovered within two days from the estimated time of explosion. The first NIR spectrum was taken merely 2.3 days after explosion and may be the earliest NIR spectrum yet obtained of a SN Ia. The most striking features in the spectrum are several NIR CI lines, and the CI {lambda}1.0693um line is the strongest ever observed in a SN Ia. Interestingly, no strong optical CII counterparts were found, even though the optical spectroscopic time series began early and is densely-cadenced. Except at the very early epochs, within a few days from the time of explosion, we show that the strong NIR CI compared to the weaker optical CII appears to be general in SNe Ia. iPTF13ebh is a fast decliner with {Delta}m15(B)=1.79+/-0.01, and its absolute magnitude obeys the linear part of the width-luminosity relation. It is therefore categorized as a "transitional" event, on the fast-declining end of normal SNe Ia as opposed to subluminous/91bg-like objects. iPTF13ebh shows NIR spectroscopic properties that are distinct from both the normal and subluminous/91bg-like classes, bridging the observed characteristics of the two classes. These NIR observations suggest composition and density of the inner core similar to that of 91bg-like events, and a deep reaching carbon burning layer not observed in slower declining SNe Ia. There is also a substantial difference between the explosion times inferred from the early-time light curve and the velocity evolution of the SiII {lambda}0.6355um line, implying a long dark phase of ~4 days.
- ID:
- ivo://CDS.VizieR/J/ApJ/701/1347
- Title:
- Optical constants of H_2_O-ice
- Short Name:
- J/ApJ/701/1347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using new laboratory spectra, we have calculated the real and imaginary parts of the index of refraction of amorphous and crystalline H_2_O-ice from 20-150K in the wavelength range 2.5-22um (4000-455cm^-1^) and joined these results with previous measurement from 1.25 to 2.5um. These optical constants improve on previous measurements by having better temperature and spectral resolution and can be used to create model spectra for comparison to spectra of solar system objects and interstellar materials. In this wavelength range, the infrared band shapes and positions of amorphous H_2_O-ice are strongly dependent on deposition temperature. Amorphous and crystalline H_2_O-ice have distinctive spectral bands at all wavelengths in this region with bands weakening and shifting to shorter wavelength in amorphous H_2_O-ice compared to crystalline H_2_O-ice. Some notable exceptions are the band near 6um, which is stronger in amorphous H2O-ice, and the bands near 4.5um and 12.5um, which shift to longer wavelength in amorphous H_2_O-ice.
- ID:
- ivo://CDS.VizieR/J/ApJ/899/14
- Title:
- Optical & FeII sources in Supernova remnant with HST
- Short Name:
- J/ApJ/899/14
- Date:
- 14 Mar 2022 07:07:21
- Publisher:
- CDS
- Description:
- NGC6946 is a high-star-formation-rate, face-on, spiral galaxy that has hosted 10 supernovae since 1917. Not surprisingly, a large number of supernova remnants and candidates have been identified either as optical nebulae with high [SII]:H{alpha} line ratios (147) or as compact non-thermal radio sources (35). However, there are only seven overlaps between these two samples. Here, we apply [FeII] 1.644{mu}m emission as a new diagnostic to search for supernova remnants in an attempt to resolve this discrepancy. [FeII] is expected to be relatively strong in the radiative shocks of supernova remnants and almost absent in HII regions. It is less susceptible to the effects of absorption along the line of sight than the optical lines normally used to identify remnants. Using data from the WFC3 camera on Hubble Space Telescope (HST), we identify 132 [FeII] emission nebulae in NGC6946 as likely supernova remnants. Of these, 54 align with previously known optical supernova remnants. The remaining 78 objects are new; of these 44 are visible in new HST imagery in H{alpha} and [SII]. This brings the total number of supernova remnant candidates (from optical and/or IR data) in NGC6946 to 225. A total of 14 coincidences with radio supernova remnant candidates (out of 30 in our search area) are found in this expanded list. The identification of so many new remnant candidates validates the use of [FeII] imagery for finding remnants, and suggests that previous remnant searches in other galaxies may be far from complete.
- ID:
- ivo://CDS.VizieR/J/MNRAS/472/334
- Title:
- Optical/MIR properties of Type 1 AGNs
- Short Name:
- J/MNRAS/472/334
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigated the connection between the mid-infrared (MIR) and optical spectral characteristics in a sample of 82 Type 1 active galactic nuclei (AGNs), observed with Infrared Spectrometer on Spitzer (IRS) and Sloan Digital Sky Survey (SDSS, DR12). We found several interesting correlations between optical and MIR spectral properties: (i) as starburst significators in MIR increase, the equivalent widths (EWs) of optical lines H{beta}NLR and FeII, increase as well; (ii) as MIR spectral index increases, EW([OIII]) decreases, while fractional contribution of AGN (RAGN) is not connected with EW([OIII]); (iii) The log([OIII]5007/H{beta}NLR) ratio is weakly related to the fractional contribution of polycyclic aromatic hydrocarbons (RPAHs). We compare the two different MIR and optical diagnostics for starburst contribution to the overall radiation (RPAH and Baldwin, Philips & Terlevich diagram, respectively). The significant differences between optical and MIR starburst diagnostics were found. The starburst influence to observed correlations between optical and MIR parameters is discussed.
- ID:
- ivo://CDS.VizieR/J/A+A/431/779
- Title:
- Optical/near-IR atlas of OH/IR stars
- Short Name:
- J/A+A/431/779
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present optical and near-infrared finding charts, accurate astrometry (~1") and single-epoch near-infrared photometry for 371 IRAS sources, 96% of those included in the so-called "Arecibo sample of OH/IR stars" (Eder et al., 1988ApJS...66..183E; Lewis et al., 1990ApJ...362..634L; Chengalur et al., 1993, Cat. <J/ApJS/89/189>). The main photometric properties of the stars in the sample are presented and discussed as well as the problems found during the process of identification of the optical/near-infrared counterparts. In addition, we also identify suitable reference stars in each field to be used for differential photometry purposes in the future.
- ID:
- ivo://CDS.VizieR/J/ApJ/720/679
- Title:
- Optical spectroscopy in Cygnus X region
- Short Name:
- J/ApJ/720/679
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new images and photometry of the massive star-forming complex Cygnus X obtained with the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer for Spitzer (MIPS) on board the Spitzer Space Telescope. A combination of IRAC, MIPS, UKIRT Deep Infrared Sky Survey, and Two Micron All Sky Survey data are used to identify and classify young stellar objects (YSOs). Of the 8231 sources detected exhibiting infrared excess in Cygnus X North, 670 are classified as class I and 7249 are classified as class II. Using spectra from the FAST Spectrograph at the Fred L. Whipple Observatory and Hectospec on the MMT, we spectrally typed 536 sources in the Cygnus X complex to identify the massive stars. We find that YSOs tend to be grouped in the neighborhoods of massive B stars (spectral types B0 to B9).
- ID:
- ivo://CDS.VizieR/J/A+A/458/173
- Title:
- Optical spectroscopy of 253 IRAS sources
- Short Name:
- J/A+A/458/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the optical spectral properties of a sample of stars showing far infrared colours similar to those of well-known planetary nebulae. The large majority of them were unidentified sources or poorly known in the literature at the time when this spectroscopic survey started, some 15 years ago. We present low-resolution optical spectroscopy, finding charts and improved astrometric coordinates of a sample of 253 IRAS sources.
- ID:
- ivo://CDS.VizieR/J/A+A/306/924
- Title:
- Optical spectrum of HR 4049
- Short Name:
- J/A+A/306/924
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution optical spectra (UES/WHT) of the extreme metal-poor post-AGB star HR 4049 were obtained at four different orbital phases. The spectra cover the wavelength region from 3650A to 10850A at a resolution of R=5.2x10^4^. These observations are supplemented with four high-resolution spectra of the NaI D1 & D2 and CaII K lines at R=~10^5^ (CAT/CES). The optical spectrum shows 217 spectral lines: the Balmer series (H{alpha} - H35), the Paschen series (P9 - P23), NI, OI and numerous CI lines. We show that the lines of H{alpha}, H{beta}, H{gamma} and NaI D show significant changes in profile between different observation dates. Nine components were identified in the profile of the NaI D lines of which three are circumstellar and six interstellar. The stronger CI lines are asymmetric and we derive a post-AGB mass-loss of {dot}(M)=6+/-4x10^-7^M_{sun}_/yr from the asymmetry. The [OI]6300A line has been detected in emission at the system velocity and we argue that the emission is from an almost edge-on disk with a radius of about 20R_*_. HR 4049 is at J2000 position: 00 42 45.8 - 20 21 36
