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891. Global energetics of solar flares. VIII.
ID:
ivo://CDS.VizieR/J/ApJ/881/1
Title:
Global energetics of solar flares. VIII.
Short Name:
J/ApJ/881/1
Date:
10 Dec 2021
Publisher:
CDS
Description:
One of the key problems in solar flare physics is the determination of the low-energy cut-off: the value that determines the energy of nonthermal electrons and hence flare energetics. We discuss different approaches to determine the low-energy cut-off in the spectrum of accelerated electrons: (I) the total electron number model, (II) the time-of-flight model (based on the equivalence of the time-of-flight and the collisional deflection time), (III) the warm target model of Kontar et al., and (IV) the model of the spectral cross-over between thermal and nonthermal components. We find that the first three models are consistent with a low-energy cutoff with a mean value of ~10keV, while the cross-over model provides an upper limit for the low-energy cutoff with a mean value of ~21keV. Combining the first three models we find that the ratio of the nonthermal energy to the dissipated magnetic energy in solar flares has a mean value of qE=0.57{+/-}0.08, which is consistent with an earlier study based on the simplified approximation of the warm target model alone (qE=0.51{+/-}0.17). This study corroborates the self-consistency between three different low-energy cutoff models in the calculation of nonthermal flare energies.
892. Global HI content from a stacking experiment
ID:
ivo://CDS.VizieR/J/A+A/580/A43
Title:
Global HI content from a stacking experiment
Short Name:
J/A+A/580/A43
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the atomic neutral hydrogen (HI) content of ~1600 galaxies up to z~0.1 using stacking techniques. The observations were carried out with the Westerbork Synthesis Radio Telescope (WSRT) in the area of the SDSS South Galactic Cap (SSGC), where we selected a galaxy sample from the SDSS spectroscopic catalog. Multi-wavelength information is provided by SDSS, NVSS, GALEX, and WISE. We use the collected information to study HI trends with color, star-forming, and active galactic nuclei (AGN) properties. Using near-UV (NUV)-r colors, galaxies are divided into blue cloud, green valley and red sequence galaxies.
893. Global SFR density over 0.7<z<1.9
ID:
ivo://CDS.VizieR/J/ApJ/696/785
Title:
Global SFR density over 0.7<z<1.9
Short Name:
J/ApJ/696/785
Date:
21 Oct 2021
Publisher:
CDS
Description:
We determine the global star formation rate (SFR) density at 0.7<z<1.9 using emission-line-selected galaxies identified in Hubble Space Telescope-Near Infrared Camera and Multi-Object Spectrograph (HST-NICMOS) grism spectroscopy observations. Observing in a pure parallel mode throughout HST Cycles 12 and 13, our survey covers ~104arcmin^2^ from which we select 80 galaxies with likely redshifted H{alpha} emission lines. In several cases, a somewhat weaker [OIII] doublet emission is also detected.
894. Globules and pillars in Cygnus X
ID:
ivo://CDS.VizieR/J/A+A/653/A108
Title:
Globules and pillars in Cygnus X
Short Name:
J/A+A/653/A108
Date:
22 Feb 2022
Publisher:
CDS
Description:
IRAS 20319+3958 in Cygnus X South is a rare example of a free-floating globule (mass ~240M_{sun}_, length ~1.5pc) with an internal HII region created by the stellar feedback of embedded intermediate-mass stars, in particular, one Herbig Be star. In Schneider et al. (2012A&A...542L..18S) and Djupvik et al. (2017A&A...599A..37D, Cat. J/A+A/599/A37), we proposed that the emission of the far-infrared (FIR) lines of [CII] at 158um and [OI] at 145um in the globule head are mostly due to an internal photodissociation region (PDR). Here, we present a Herschel/HIFI [CII] 158um map of the whole globule and a large set of other FIR lines (mid-to high-J CO lines observed with Herschel/PACS and SPIRE, the [OI] 63um line and the ^12^CO 16->15 line observed with upGREAT on SOFIA), covering the globule head and partly a position in the tail. The [CII] map revealed that the whole globule is probably rotating. Highly collimated, high-velocity [CII] emission is detected close to the Herbig Be star. We performed a PDR analysis using the KOSMA-{tau}PDR code for one position in the head and one in the tail. The observed FIR lines in the head can be reproduced with a two-component model: an extended, non-clumpy outer PDR shell and a clumpy, dense, and thin inner PDR layer, representing the interface between the HII region cavity and the external PDR. The modelled internal UV field of ~2500Go is similar to what we obtained from the Herschel FIR fluxes, but lower than what we estimated from the census of the embedded stars. External illumination from the ~30pc distant Cyg OB2 cluster, producing an UV field of ~150-600Go as an upper limit, is responsible for most of the [CII] emission. For the tail, we modelled the emission with a non-clumpy component, exposed to a UV-field of around 140Go.
895. Gl 49 radial velocities and activity indicators
ID:
ivo://CDS.VizieR/J/A+A/624/A123
Title:
Gl 49 radial velocities and activity indicators
Short Name:
J/A+A/624/A123
Date:
21 Oct 2021
Publisher:
CDS
Description:
Small planets around low-mass stars often show orbital periods in a range that corresponds to the temperate zones of their host stars which are therefore of prime interest for planet searches. Surface phenomena such as spots and faculae create periodic signals in radial velocities and in observational activity tracers in the same range, so they can mimic or hide true planetary signals. We aim to detect Doppler signals corresponding to planetary companions, determine their most probable orbital configurations, and understand the stellar activity and its impact on different datasets. We analyzed 22 years of data of the M1.5V-type star Gl 49 (BD+61 195) including HARPS-N and CARMENES spectrographs, complemented by APT2 and SNO photometry. Activity indices are calculated from the observed spectra, and all datasets are analyzed with periodograms and noise models. We investigated how the variation of stellar activity imprints on our datasets. We further tested the origin of the signals and investigate phase shifts between the different sets. To search for the best-fit model we maximize the likelihood function in a Markov chain Monte Carlo approach. As a result of this study, we are able to detect the super-Earth Gl 49b with a minimum mass of 5.6M_{earth}_. It orbits its host star with a period of 13.85d at a semi-major axis of 0.090au and we calculate an equilibrium temperature of 350K and a transit probability of 2.0%. The contribution from the spot-dominated host star to the different datasets is complex, and includes signals from the stellar rotation at 18.86d, evolutionary timescales of activity phenomena at 40-80d, and a long-term variation of at least four years.
896. Gl686 RV curves and BVR photometry
ID:
ivo://CDS.VizieR/J/A+A/622/A193
Title:
Gl686 RV curves and BVR photometry
Short Name:
J/A+A/622/A193
Date:
21 Oct 2021
Publisher:
CDS
Description:
The HArps-n red Dwarf Exoplanet Survey is providing a major contribution to the widening of the current statistics of low-mass planets, through the in-depth analysis of precise radial velocity measurements in a narrow range of spectral sub-types. Using the HARPS-N spectrograph we reach the precision needed to detect small planets with a few earth masses. Our survey is mainly focused on the M-dwarf population of the northern hemisphere. As part of that programme, we obtained radial velocity measurements of Gl686, an M1 dwarf at d=8.2pc. These measurements show a dispersion much in excess of their internal errors. The analysis of data obtained within an intensive observing campaign, demonstrates that the excess dispersion is due to a coherent signal, with a period of 15.53d. Almost simultaneous photometric observations were carried out within the APACHE and EXORAP programmes to characterize the stellar activity and to distinguish periodic variations related to activity from signals due to the presence of planetary companions, complemented also with ASAS photometric data. We used a Bayesian framework to estimate the orbital parameters and the planet minimum mass, and to properly treat the activity noise. We took advantage of the available radial velocity measurements for this target from other observing campaigns. The analysis of the radial velocity composite time series from the HIRES, HARPS and HARPS-N spectrographs, consisting of 198 measurements taken over 20 years, enabled us to address the nature of periodic signals and also to characterize stellar physical parameters (mass, temperature and rotation). We report the discovery of a super-Earth orbiting at a distance of 0.092AU from the host star Gl686. Gl686 b has a minimum mass of 7.1+/-0.9M_{Earth} and an orbital period of 15.532+/-0.002d. The analysis of the activity indexes, correlated noise through a Gaussian process framework and photometry, provides an estimate of the stellar rotation period at 37d, and highlights the variability of the spot configuration during the long timespan covering 20yrs. The observed periodicities around 2000d likely point to the existence of an activity cycle.
897. GMASS photometry
ID:
ivo://CDS.VizieR/J/A+A/549/A63
Title:
GMASS photometry
Short Name:
J/A+A/549/A63
Date:
21 Oct 2021
Publisher:
CDS
Description:
We designed a spectroscopic observing campaign of a sample of both massive, quiescent and star-forming galaxies at z>1.4, called Galaxy Mass Assembly ultra-deep Spectroscopic Survey (GMASS). To determine redshifts and physical properties, such as metallicity, dust content, dynamical masses, and star formation history, we performed ultra-deep spectroscopy with the red-sensitive optical spectrograph FORS2 at the VLT. Our sample consists of objects, within the CDFS/GOODS area, detected at 4.5 micron, to be sensitive to stellar mass rather than star formation intensity. The spectroscopic targets were selected with a photometric redshift constraint (z>1.4) and magnitude constraints (B(AB)<26, I(AB)<26.5), which should ensure that these are faint, distant, and fairly massive galaxies. Up to 30 hours of spectroscopy of 174 spectroscopic targets and 70 additional objects enabled us to determine 210 redshifts, of which 145 are at z>1.4. We publicly release the redshifts and reduced spectra.
898. GMOS-IFU spectroscopy of dwarf galaxy HS 2236+1344
ID:
ivo://CDS.VizieR/J/A+A/569/A110
Title:
GMOS-IFU spectroscopy of dwarf galaxy HS 2236+1344
Short Name:
J/A+A/569/A110
Date:
21 Oct 2021
Publisher:
CDS
Description:
The main goal of this study is to carry out a spatially resolved investigation of the warm interstellar medium (ISM) in the extremely metal-poor blue compact dwarf galaxy HS 2236+1344. Special emphasis is laid on the analysis of the spatial distribution of chemical abundances, emission-line ratios and kinematics of the ISM, and to the recent star-forming activity in this galaxy.
899. GMOS spectroscopic obs. of SNR candidates in M83
ID:
ivo://CDS.VizieR/J/ApJ/839/83
Title:
GMOS spectroscopic obs. of SNR candidates in M83
Short Name:
J/ApJ/839/83
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results from a spectrophotometric study sampling the 300 candidate supernova remnants (SNRs) in M83 identified through optical imaging with Magellan/IMACS and Hubble Space Telescope/WFC3. Of the 118 candidates identified based on a high [SII]{lambda}{lambda}6716,6731 to H{alpha} emission ratio, 117 show spectroscopic signatures of shock-heated gas, confirming them as SNRs-the largest uniform set of SNR spectra for any galaxy. Spectra of 22 objects with a high [OIII]{lambda}5007 to H{alpha} emission ratio, selected in an attempt to identify young ejecta-dominated SNRs like Cas A, reveal only one (previously reported) object with the broad (1000km/s) emission lines characteristic of ejecta-dominated SNRs, beyond the known SN1957D remnant. The other 20 [OIII]-selected candidates include planetary nebulae, compact HII regions, and one background QSO. Although our spectroscopic sample includes 22 SNRs smaller than 11pc, none of the other objects show broad emission lines; instead their spectra stem from relatively slow (~200km/s) radiative shocks propagating into the metal-rich interstellar medium of M83. With six SNe in the past century, one might expect more of M83's small-diameter SNRs to show evidence of ejecta; this appears not to be the case. We attribute their absence to several factors, including that SNRs expanding into a dense medium evolve quickly to the ISM-dominated phase, and that SNRs expanding into regions already evacuated by earlier SNe are probably very faint.
900. GO And, 84 UMa, kappa Psc ESPaDOnS spectra
ID:
ivo://CDS.VizieR/J/A+A/655/A106
Title:
GO And, 84 UMa, kappa Psc ESPaDOnS spectra
Short Name:
J/A+A/655/A106
Date:
11 Mar 2022 13:28:01
Publisher:
CDS
Description:
The aim of this work is to determine fundamental parameters of three Ap stars, GO And (HD 4778), {kappa} Psc (HD 220825), and 84 UMa (HD 120198), using spectroscopic techniques. By analysing these stars, we complete the sample of Ap stars for which fundamental parameters have additionally been derived by means of interferometry. This enables a cross-comparison of results derived by direct and indirect methods. Our study is based on the analysis of high-resolution spectra with a high signal-to-noise ratio that were obtained with ESPaDOnS spectrograph. We used an iterative method of fundamental parameter determinations that includes self-consistent modelling of the stellar atmosphere, taking individual abundances of chemical elements into account and subsequently fitting a theoretical spectral energy distribution to the observed distribution. The quality of the spectroscopic determinations was evaluated through a comparison with the interferometric results. For all investigated stars we determined fundamental parameters and derived chemical abundances that turn to be typical for Ap stars and are characterised mainly by gradual increase of heavy elements atmospheric abundance from an order of magnitude for iron peak elements up to very significant excesses of 3-4dex of the rare-earth elements relative to the solar values. The only exception is Ba which abundance is close to the solar one. There is also a significant He deficiency in the atmospheres of HD 120198 and HD 220825, whereas He abundance in HD 4778 is close to the solar one. We do not find significant Fe and Cr stratification. Using these abundances we constructed self-consistent atmospheric models for each star. The effect of the surface chemical inhomogeneity on the derived fundamental parameters did not exceed +/-100K in effective temperature which lies within a range of errors in similar self-consistent analyses of Ap stars. Finally, we compared spectroscopically derived effective temperatures, radii, and luminosity for 13 out of 14 Ap stars in benchmarking sample with the interferometric results. While radii and luminosity agree within the quoted errors of both determinations, spectroscopic effective temperatures are higher than the interferometric ones for stars with Teff>9000K. The observed hydrogen line profiles favour the spectroscopically derived temperatures.

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