- ID:
- ivo://CDS.VizieR/J/AJ/155/104
- Title:
- MEGaSaURA. I. The sample and the spectra
- Short Name:
- J/AJ/155/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce Project MEGaSaURA: the Magellan Evolution of Galaxies Spectroscopic and Ultraviolet Reference Atlas. MEGaSaURA comprises medium-resolution, rest-frame ultraviolet spectroscopy of N=15 bright gravitationally lensed galaxies at redshifts of 1.68<z<3.6, obtained with the MagE spectrograph on the Magellan telescopes. The spectra cover the observed-frame wavelength range 3200<{lambda}_o_<8280{AA}; the average spectral resolving power is R=3300. The median spectrum has a signal-to- noise ratio (S/N)=21 per resolution element at 5000{AA}. As such, the MEGaSaURA spectra have superior S/N and wavelength coverage compared to what COS/HST provides for starburst galaxies in the local universe. This paper describes the sample, the observations, and the data reduction. We compare the measured redshifts for the stars, the ionized gas as traced by nebular lines, and the neutral gas as traced by absorption lines; we find the expected bulk outflow of the neutral gas, and no systemic offset between the redshifts measured from nebular lines and the redshifts measured from the stellar continuum.
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- ID:
- ivo://CDS.VizieR/VI/99
- Title:
- Merged Log of IUE Observations
- Short Name:
- VI/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The log contains a summary of all IUE Newly Extracted Spectra (INES), which resulted from a post-processing effort at Vilspa. It was constructed by using verified data from the IUE Final Archive Master Catalogue. The observations cover the whole life of the satellite, from March 1978 to September 1996.
- ID:
- ivo://CDS.VizieR/VI/75
- Title:
- Merged Log of IUE Observations
- Short Name:
- VI/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The log contains data from January 26, 1978 through Dec. 92. It is sorted by right ascension.
- ID:
- ivo://CDS.VizieR/J/ApJ/871/151
- Title:
- METAL Hubble program. I. Initial results
- Short Name:
- J/ApJ/871/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Metal Evolution, Transport, and Abundance in the Large Magellanic Cloud (METAL) is a large cycle 24 program on the Hubble Space Telescope aimed at measuring dust extinction properties and interstellar depletions in the Large Magellanic Cloud (LMC) at half-solar metallicity. The 101-orbit program is composed of Cosmic Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph (STIS) spectroscopy toward 33 LMC massive stars between 1150 and 3180{AA} and parallel Wide Field Camera 3 (WFC3) imaging in seven near-UV to near-IR filters. The fraction of silicon in the gas phase (depletion) obtained from the spectroscopy decreases with increasing hydrogen column density. Depletion patterns for silicon differ between the Milky Way, LMC, and Small Magellanic Cloud (SMC), with the silicon depletion level offsetting almost exactly the metallicity differences, leading to constant gas-phase abundances in those galaxies for a given hydrogen column density. The silicon depletion correlates linearly with the absolute-to-selective extinction, RV, indicating a link between gas depletion and dust grain size. Extinction maps are derived from the resolved stellar photometry in the parallel imaging, which can be compared to far-IR images from Herschel and Spitzer to estimate the emissivity of dust at LMC metallicity. The full METAL sample of depletions, UV extinction curves, and extinction maps will inform the abundance, size, composition, and optical properties of dust grains in the LMC, comprehensively improve our understanding of dust properties, and improve the accuracy with which dust-based gas masses, star formation rates, and star formation histories in nearby and high-redshift galaxies are estimated. This overview paper describes the goals, design, data reduction, and initial results of the METAL survey.
- ID:
- ivo://CDS.VizieR/J/A+A/404/689
- Title:
- Metallicities of Slowly Pulsating B stars
- Short Name:
- J/A+A/404/689
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derived the stellar parameters (angular diameters, effective temperatures, metallicities) and interstellar reddenings for 20 Slowly Pulsating B (SPB) and 34 reference stars observed during the IUE satellite mission. The parameters were derived by means of an algorithmic procedure of fitting theoretical flux distributions to the low-resolution IUE spectra and optical spectrophotometric observations. Since the metallicity [m/H] has a special importance for pulsating B type stars, we focused our attention on that parameter. We found that the mean value of the metallicity of the considered SPB and reference stars amounts to [m/H]~-0.20. The results only slightly depend on the reduction procedure used for the IUE images (NEWSIPS and INES). The metal abundances obtained in this paper are in accordance with the average value of -0.2dex for stars in the solar neighborhood recently reported by other investigators.
- ID:
- ivo://CDS.VizieR/J/ApJ/763/L36
- Title:
- MgII and FeII flux of the blazar 3C 454.3
- Short Name:
- J/ApJ/763/L36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of a statistically significant flare-like event in the MgII {lambda}2800 emission line of 3C 454.3 during the outburst of autumn 2010. The highest levels of emission line flux recorded over the monitoring period (2008-2011) coincide with a superluminal jet component traversing through the radio core. This finding crucially links the broad emission line fluctuations to the non-thermal continuum emission produced by relativistically moving material in the jet and hence to the presence of broad-line region clouds surrounding the radio core. If the radio core were located at several parsecs from the central black hole, then our results would suggest the presence of broad-line region material outside the inner parsec where the canonical broad-line region is envisaged to be located. We briefly discuss the implications of broad emission line material ionized by non-thermal continuum in the context of virial black hole mass estimates and gamma-ray production mechanisms.
- ID:
- ivo://CDS.VizieR/J/ApJ/794/156
- Title:
- MgII/FeII absorption profile for 0.3<z<1.4 galaxies
- Short Name:
- J/ApJ/794/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze Mg II {lambda}{lambda}2796, 2803 and Fe II {lambda}{lambda}2586, 2600 absorption profiles in individual spectra of 105 galaxies at 0.3<z<1.4. The galaxies, drawn from redshift surveys of the GOODS fields and the Extended Groth Strip, sample the range in star formation rates (SFRs) occupied by the star-forming sequence with stellar masses log M_*_/M_{sun}_>~9.6 down to SFR>~2 M_{sun}_/yr at 0.3<z<0.7. Using the Doppler shifts of Mg II and Fe II absorption as tracers of cool gas kinematics, we detect large-scale winds in 66+/-5% of the galaxies. Hubble Space Telescope Advanced Camera for Surveys imaging and our spectral analysis indicate that the outflow detection rate depends primarily on galaxy orientation: winds are detected in ~89% of galaxies having inclinations (i) <30{deg} (face-on), while the wind detection rate is ~45% in objects having i>50{deg} (edge-on). Combined with the comparatively weak dependence of wind detection rate on intrinsic galaxy properties, this implies that biconical outflows are ubiquitous in normal, star-forming galaxies at z~0.5. We find that wind velocity is correlated with galaxy M_*_ at 3.4{sigma} significance, while outflow equivalent width is correlated with SFR at 3.5{sigma} significance, suggesting hosts with higher SFR launch more material and/or generate a larger velocity spread for the absorbing clouds. Assuming the gas is driven into halos with isothermal density profiles, the wind velocities (~200-400 km/s) permit escape from the halo potentials only for the lowest-M_*_systems in the sample. However, the gas carries sufficient energy to reach distances >~50 kpc, and may therefore be a viable source of material for the massive, cool circumgalactic medium around bright galaxies at z~0.
- ID:
- ivo://CDS.VizieR/J/A+A/430/303
- Title:
- MgII-K line fluxes in cool active and quiet stars
- Short Name:
- J/A+A/430/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The MgIIk emission line is a good indicator of the level of chromospheric activity in late-type stars. We investigate the dependence of this activity indicator on fundamental stellar parameters. To this purpose we use IUE observations of the MgIIk line in 225 late-type stars of luminosity classes I-V, with different levels of chromospheric activity. We first re-analyse the relation between MgIIk line luminosity and stellar absolute magnitude, performing linear fits to the points. The ratio of MgII surface flux to total surface flux is found to be independent of stellar luminosity for evolved stars and to increase with decreasing luminosity for dwarfs. We also analyse the MgIIk line surface flux-metallicity connection.
- ID:
- ivo://CDS.VizieR/J/A+A/374/1085
- Title:
- Mg II K line Wilson-Bappu relationship
- Short Name:
- J/A+A/374/1085
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An investigation is carried out on the Wilson-Bappu effect in the MgII K line at 2796.34{AA}. The work is based on a selection of 230 stars observed by both the IUE and HIPPARCOS satellites, covering a wide range of spectral types (F to M) and absolute visual magnitudes (-5.4<=M_V_<=9.0). A semi-automatic procedure is used to measure the line widths, which applies also in the presence of strong central absorption reversal. The Wilson-Bappu relationship here provided is considered to represent an improvement over previous recent results for the considerably larger data sample used, as well as for a proper consideration of the measurement errors. No evidence has been found for a possible dependence of the WB effect on stellar metallicity and effective temperature.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/484
- Title:
- MgII UV feature in T Tauri stars
- Short Name:
- J/MNRAS/448/484
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The atmospheric structure of T Tauri stars (TTSs) and its connection with the large-scale outflow is poorly known. Neither the effect of the magnetically mediated interaction between the star and the disc is well understood. The MgII multiplet is a fundamental tracer of TTSs atmospheres and outflows, and is the strongest feature in the near-ultraviolet spectrum of TTSs. The International Ultraviolet Explorer and Hubble Space Telescope data archives provide a unique set to study the main physical compounds contributing to the line profile and to derive the properties of the line formation region. The MgII profiles of 44 TTSs with resolution 13000-30000 are available in these archives. In this work, we use this data set to measure the main observables: flux, broadening, asymmetry, terminal velocity of the outflow, and the velocity of the discrete absorption components. For some few sources repeated observations are available and variability has been studied. There is a warm wind that at sub-au scales absorbs the blue wing of the MgII profiles. The main result found in this work is the correlation between the line broadening, MgII flux, terminal velocity of the flow and accretion rate. Both outflow and magnetospheric plasma contribute to the MgII flux. The flux-flux correlation between MgII and CIV or HeII is confirmed; however, no correlation is found between the MgII flux and the UV continuum or the H_2_ emission.