Search

Start Over Subject spectroscopy Content Level Research
1881. Optical and HI properties of galaxies in voids
ID:
ivo://CDS.VizieR/J/AJ/144/16
Title:
Optical and HI properties of galaxies in voids
Short Name:
J/AJ/144/16
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have carefully selected a sample of 60 galaxies that reside in the deepest underdensities of geometrically identified voids within the Sloan Digital Sky Survey. HI imaging of 55 galaxies with the Westerbork Synthesis Radio Telescope reveals morphological and kinematic signatures of ongoing interactions and gas accretion. We probe a total volume of 485Mpc^3^ within the voids, with an angular resolution of 8kpc at an average distance of 85Mpc. We reach column density sensitivities of 5x10^19^/cm^-2^, corresponding to an HI mass limit of 3x10^8^M_{sun}_. We detect HI in 41 galaxies, with total masses ranging from 1.7x10^8^ to 5.5x10^9^M_{sun}_. The upper limits on the 14 non-detections are not inconsistent with their luminosities, given their expected HI mass-to-light ratios. We find that the void galaxies are generally gas-rich, low-luminosity, blue disk galaxies, with optical and HI properties that are not unusual for their luminosity and morphology. The sample spans a range of absolute magnitudes (-16.1>M_r_>-20.4) and colors (0.06<g-r<0.87), and includes disk and irregular galaxies. We also identify three as early-type galaxies, all of which are not detected in HI. All galaxies have stellar masses less than 3x10^10^M_{sun}_, and many have kinematic and morphological signs of ongoing gas accretion, suggesting that the void galaxy population is still in the process of assembling. The small-scale clustering in the void, within 600kpc and 200km/s, is similar to that in higher density regions, and we identify 18 HI-rich neighboring galaxies in the voids. Most are within 100kpc and 100km/s of the targeted galaxy, and we find no significant population of HI-rich low-luminosity galaxies filling the voids, contrary to what is predicted by simulations.
1882. Optical and IR spectroscopy of Europa
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.
1883. Optical and IUE spectra of NGC 7026
ID:
ivo://CDS.VizieR/J/ApJ/614/745
Title:
Optical and IUE spectra of NGC 7026
Short Name:
J/ApJ/614/745
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigated spectroscopic data of the extended planetary nebula NGC 7026 in the wavelengths 3700-10050{AA}, secured with the Hamilton Echelle Spectrograph at Lick Observatory. This optical wavelength spectrum has been analyzed along with the International Ultraviolet Explorer (IUE) UV spectral data.
1884. Optical and NIR spectra and LCs of SN2016ija
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.
1885. Optical and NIR spectra of SN iPTF13ebh
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.
1886. Optical and UV follow-up of 1ES 1927+654
ID:
ivo://CDS.VizieR/J/ApJ/883/94
Title:
Optical and UV follow-up of 1ES 1927+654
Short Name:
J/ApJ/883/94
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the sudden optical and ultraviolet (UV) brightening of 1ES1927+654, which until now was known as a narrow-line active galactic nucleus (AGN). 1ES 1927+654 was part of the small and peculiar class of "true Type-2" AGNs that lack broad emission lines and line-of-sight obscuration. Our high-cadence spectroscopic monitoring captures the appearance of a blue, featureless continuum, followed several weeks later by the appearance of broad Balmer emission lines. This timescale is generally consistent with the expected light travel time between the central engine and the broadline emission region in (persistent) broadline AGN. Hubble Space Telescope spectroscopy reveals no evidence for broad UV emission lines (e.g., CIV{lambda}1549, CIII]{lambda}1909, MgII{lambda}2798), probably owing to dust in the broadline emission region. To the best of our knowledge, this is the first case where the lag between the change in continuum and in broadline emission of a "changing look" AGN has been temporally resolved. The nature and timescales of the photometric and spectral evolution disfavor both a change in line-of-sight obscuration and a change of the overall rate of gas inflow as driving the drastic spectral transformations seen in this AGN. Although the peak luminosity and timescales are consistent with those of tidal disruption events seen in inactive galaxies, the spectral properties are not. The X-ray emission displays a markedly different behavior, with frequent flares on timescales of hours to days, and will be presented in a companion publication.
1887. Optical and UV Spectrum of KQ Pup
ID:
ivo://CDS.VizieR/J/A+AS/92/685
Title:
Optical and UV Spectrum of KQ Pup
Short Name:
J/A+AS/92/685
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
1888. Optical chromospheric activity of V711 Tau
ID:
ivo://CDS.VizieR/J/MNRAS/449/1380
Title:
Optical chromospheric activity of V711 Tau
Short Name:
J/MNRAS/449/1380
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present long-term high-resolution spectroscopic observations of the very active RS Canum Venaticorum-type star V711 Tau, obtained during several observing runs from 1998 to 2004, and study its chromospheric activity. Using the spectral subtraction technique, several optical chromospheric activity indicators [including the He I D_3_, Na I D_1_, D_2_, H{alpha} and Ca II infrared triplet (IRT) lines] formed at different atmospheric heights are analysed. Strong chromospheric emission supports earlier results that indicate that V711 Tau is a very active system. Two large optical flares were detected during our observations. The results suggest that the main part of chromospheric emission is attributed to the primary star of the system. The secondary also presents weak emission but is less active. The ratios of EW_8542_/EW_8498_ indicate that CaII IRT emission arises predominantly from plage-like regions. We have found rotational modulation of chromospheric activity in the H{alpha} and CaII IRT lines, which suggests the presence of the chromospheric active longitudes over the surface of V711 Tau. Two active longitudes separated by about 180{deg} were observed to dominate the activity, and the so-called flip-flop phenomenon was seen during our observations. Moreover, the chromospheric activity level shows a long-term variation that gradually increases from a deep minimum near the year 2002. A close spatial connection of photospheric spots and chromospheric active regions in both short and long timescales was found for V711 Tau.
1889. Optical classification of southern ULIRGs
ID:
ivo://CDS.VizieR/J/MNRAS/414/702
Title:
Optical classification of southern ULIRGs
Short Name:
J/MNRAS/414/702
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of the optical spectral properties of 115 ultraluminous infrared galaxies (ULIRGs) in the southern sky. Using the optical spectra obtained at the Cerro Tololo Inter-American Observatory (CTIO) 4m telescope and provided by the Two-degree Field (2dF) Galaxy Redshift Survey and the Six-degree Field (6dF) Galaxy Survey, we measure emission linewidths and fluxes for spectral classification.
1890. Optical constants of H_2_O-ice
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.

Limit your search

more »

more »

more »

more »