- ID:
- ivo://CDS.VizieR/J/A+A/367/597
- Title:
- ups Her, phi Her & HR 7018 abundances
- Short Name:
- J/A+A/367/597
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Elemental abundances analyses are performed for the Mercury-Manganese stars {upsilon} Her, {phi} Her, and HR 7018 consistent with previous studies of this series using spectrograms obtained with Reticon and CCD detectors. Comparisons of the first two analyses with those performed using coadded photographic plates show the general consistency of the derived elemental abundances. For {upsilon} Her and for {phi} Her, abundances were newly found for O, and for Al, V, Zn, and Ce, respectively. HR 7018 is discovered to be a single-lined spectroscopic binary. Its Sc abundance is the smallest of any class member with derived abundances and its Sr abundance the largest of any known HgMn star. A correlation analysis of the most complete abundance sets for 20 HgMn stars shows that the abundances of some elements are correlated with one another and some are functions of the stellar effective temperature.
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- ID:
- ivo://CDS.VizieR/J/A+A/415/273
- Title:
- UVBRI photometry and spectroscopy of AG Dra
- Short Name:
- J/A+A/415/273
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric UBVri observations of the symbiotic star AG Dra in Piwnice Observatory, Torun, Poland, are presented in tables 2 and 3. The 60cm telescope and a single-channel photoelectric photometer have been used. Table 2 lists observations with the EMI9558B photomultiplier tube from March 1996 to September 1999. Table 3 lists observations with the cooled C31034 photomultiplier tube from October 2001 to May 2003. Table 4 lists equivalent widths (EW) of the four emission lines in the spectrum of AG Dra: The Raman scattered line at 6825{AA}, H{alpha}, H{beta} and He II 4686{AA}. The spectroscopic observations have been performed in Tartu Observatory, Estonia, using the 1.5m telescope and a Cassegrain spectrograph. The time interval extends from September 1997 to March 2003.
- ID:
- ivo://CDS.VizieR/J/A+A/370/426
- Title:
- UVES Spectrum of APM BR J0307-4945
- Short Name:
- J/A+A/370/426
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first high-resolution (6.2 to 7.7km/s FWHM) spectra of the APM BR J0307-4945 quasar at z_em_=4.73 obtained with UVES on the 8.2m VLT Kueyen telescope. We focus our analysis on a damped Lyman-{alpha} system at z_abs_=4.466, the most distant DLA system known to the present date, observed when the age of the universe was only 1.3Gyr. The following table lists the wavelengths and equivalent widths for all absorption-line features (except the telluric lines) redwards of the quasar Ly-{alpha} emission detected at 4{sigma} in equivalent width. The transition names and approximate redshifts are specified for the features we successfully identified. About 80% of the absorption lines redwards of the quasar Ly-{alpha} emission have been identified, corresponding to 13 metal-line systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/599/116
- Title:
- UV properties of absorbed quasars
- Short Name:
- J/ApJ/599/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A statistical study is presented of (1) the frequency of narrow C IV {lambda}1549 absorption lines in 1.5<=z<~3.6 radio-quiet and radio-loud quasars and (2) the UV and radio properties of the absorbed quasars. The quasar sample is unbiased with respect to absorption properties, and the radio-quiet and radio-loud subsamples are well matched in redshift and luminosity.
- ID:
- ivo://CDS.VizieR/J/ApJS/71/983
- Title:
- UV spectrum of eta Car
- Short Name:
- J/ApJS/71/983
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/MNRAS/505/963
- Title:
- Vanishing natural coronagraph of eta Car
- Short Name:
- J/MNRAS/505/963
- Date:
- 17 Jan 2022 00:16:02
- Publisher:
- CDS
- Description:
- Eta Carinae is a massive interacting binary system shrouded in a complex circumstellar environment whose evolution is the source of the long-term brightening observed during the last 80yr. An occulter, acting as a natural coronagraph, impacts observations from our perspective, but not from most other directions. Other sight-lines are visible to us through studies of the Homunculus reflection nebula. The coronagraph appears to be vanishing, decreasing the extinction towards the central star, and causing the star's secular brightening. In contrast, the Homunculus remains at an almost constant brightness. The coronagraph primarily suppresses the stellar continuum, to a lesser extent the wind lines, and not the circumstellar emission lines. This explains why the absolute values of equivalent widths (EWs) of the emission lines in our direct view are larger than those seen in reflected by the Homunculus, why the direct view absolute EWs are decreasing with time, and why lower-excitation spectral wind lines formed at larger radii (e.g FeII 4585{AA}) decrease in intensity at a faster pace than higher excitation lines that form closer to the star (e.g. H{delta}). Our main result is that the star, despite its 10-fold brightening over two decades, is relatively stable. A vanishing coronagraph that can explain both the large flux evolution and the much weaker spectral evolution. This is contrary to suggestions that the long-term variability is intrinsic to the primary star that is still recovering from the Great Eruption with a decreasing mass-loss rate and a polar wind that is evolving at a slower pace than at the equator.
- ID:
- ivo://CDS.VizieR/J/ApJS/250/3
- Title:
- Variable MgII NALs in SDSS DR14
- Short Name:
- J/ApJS/250/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Compared to high ionization CIV absorption lines, variable MgII absorption lines are rare. Using spectra from the Sloan Digital Sky Survey, we investigate the variations in MgII narrow absorption lines (NALs) for quasars with multi-epoch observations. We have compiled 8958 MgII NALs in the spectral regions from the red wings of CIV emission lines to the red wings of MgII emission lines. Among these 8958 MgII NALs, 22 variable NALs are detected with |{Delta}W_r_^{lambda}2796^|>=3{sigma}_W_ and with velocity offsets ranging from {upsilon}_r_=522 to 145513km/s. We find that: (1) the detected frequency of MgII NALs with {upsilon}_r_<=10000km/s is significantly larger than the uniformly random value expected for the MgII NALs with {upsilon}_r_>10000km/s, (2) the incidence rates of the variable MgII NALs with {upsilon}_r_<=10000km/s are much larger than those with {upsilon}_r_>10000km/s, (3) the velocity offsets of variable MgII NALs with {upsilon}_r_<=10000km/s are much smaller than the maximum velocities expected from radiation-driven outflows, and (4) the variations of variable MgII NALs with {upsilon}_r_<=10000km/s are obviously correlated with the changes in the quasar radiative output. Therefore, the 16 variable MgII NALs, whose velocities are smaller than the maximum velocities expected from radiation-driven outflows, are likely related to quasar outflows, while the 6 variable MgII NALs, whose velocities are much larger than the maximum velocities expected from radiation-driven outflows, possibly originated in intervening gas. We also find that both the variations and fractional variations in absorption strengths are not related to the velocity offsets of MgII NALs and the time intervals between the two epochs of observations. Also, the fractional variations in absorption strengths are inversely correlated with absorption strengths. In addition, both the associated and intervening MgII NALs can significantly vary on a timescale of days.
- ID:
- ivo://CDS.VizieR/J/A+A/338/1006
- Title:
- V723 Cas equivalent widths
- Short Name:
- J/A+A/338/1006
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The monitoring of spectral evolution of the very slow nova V723 Cas started at the Asiago Astrophysical Observatory just on the announcement of discovery. In this paper the spectral evolution during the long pre-maximum stage, which lasted from August to December 1995, is reported. Emission lines of H I and Fe II were prominent in the early stage. Most of the lines were accompanied by P Cygni type absorption components. The emission lines gradually weakened with time and the absorption components developed. The mean of the blue-shifts of the absorption components with respect to the emissions was about -126km/s in September and -96km/s in December 1995. Some lines of Fe I, Fe II, Y II, Sc II, Ba II, etc. appeared in the later stage. All emission lines, except for H{alpha}, once nearly disappeared in November when the nova slightly brightened to V=~8.6. Some emission lines appeared again several days before the beginning of the final rise to maximum luminosity, then a pure absorption spectrum of F type supergiant was seen on the maximum of V=~7.1 at the middle of December. The absorption components of Si II lines at 634.7 and 637.1nm showed fairly different profiles from those of the other metallic lines, which suggests a complicated gas motion in the atmosphere. The distance and the absolute magnitude at maximum are estimated to be 2.95+/-0.7kpc and M_V_(max)=-6.1+/-0.5, respectively. The mass of the white dwarf in this system may be about 0.58+/-0.07M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/3258
- Title:
- Velocities and EW of PTF SNe Ia
- Short Name:
- J/MNRAS/444/3258
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an investigation of the optical spectra of 264 low-redshift (z<0.2) Type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory, an untargeted transient survey. We focus on velocity and pseudo-equivalent width measurements of the SiII 4130, 5972, and 6355{AA} lines, as well those of the CaII near-infrared (NIR) triplet, up to +5days relative to the SN B-band maximum light. We find that a high-velocity component of the CaII NIR triplet is needed to explain the spectrum in ~95% of SNe Ia observed before -5days, decreasing to ~80% at maximum. The average velocity of the CaII high-velocity component is ~8500km/s higher than the photospheric component. We confirm previous results that SNe Ia around maximum light with a larger contribution from the high-velocity component relative to the photospheric component in their CaII NIR feature have, on average, broader light curves and lower CaII NIR photospheric velocities. We find that these relations are driven by both a stronger high-velocity component and a weaker contribution from the photospheric CaII NIR component in broader light curve SNe Ia. We identify the presence of CII in very-early-time SN Ia spectra (before -10days), finding that >40% of SNe Ia observed at these phases show signs of unburnt material in their spectra, and that CII features are more likely to be found in SNe Ia having narrower light curves.
- ID:
- ivo://CDS.VizieR/J/ApJ/676/1109
- Title:
- Velocities of stars in the Orion Nebula Cluster
- Short Name:
- J/ApJ/676/1109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from 1351 high-resolution spectra of 1215 stars in the Orion Nebula Cluster (ONC) and the surrounding Orion 1c association, obtained with the Hectochelle multiobject echelle spectrograph on the 6.5m MMT. We confirmed 1111 stars as members, based on their radial velocity and/or H{alpha} emission. The radial velocity distribution of members shows a dispersion of {sigma}=3.1km/s. We found a substantial north-south velocity gradient and spatially coherent structure in the radial velocity distribution, similar to that seen in the molecular gas in the region. We also identified several binary and high velocity stars, a region exhibiting signs of triggered star formation, and a possible foreground population of stars somewhat older than the ONC.
