- ID:
- ivo://CDS.VizieR/J/PAZh/39/58
- Title:
- Equivalent widths of thick-disk red giants
- Short Name:
- J/PAZh/39/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The atmospheric parameters and elemental abundances for ten thick-disk red giants have been determined from high-resolution spectra by the method of model stellar atmospheres. The results of a comparative analysis of the [Na/Fe] abundances in the atmospheres of the investigated stars and thindisk red giants are presented. Sodium in the atmospheres of thick-disk red giants is shown to have no overabundances typical of thin-disk red giants.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/440/1153
- Title:
- Equivalent widths of 7 thin-disk stars
- Short Name:
- J/A+A/440/1153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In Papers I (del Peloso et al. 2005, Cat. <J/A+A/434/275>) and II (2005A&A...434..301D) we performed the first determination of the age of the Galactic thin disk from Th/Eu nucleocosmochronology. The present work aimed at reducing the age uncertainty by expanding the stellar sample with the inclusion of seven new objects. The Th and Eu abundances used in the dating procedure were obtained through spectral synthesis, and to perform the synthesis it was necessary to know the atmospheric parameters and chemical abundances of contaminating elements.
- ID:
- ivo://CDS.VizieR/J/A+A/417/269
- Title:
- Equivalent widths of two post-AGB stars
- Short Name:
- J/A+A/417/269
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In an effort to extend the still limited sample of s-process enriched post-AGB stars, high-resolution, high signal-to-noise VLT+UVES spectra of the optical counterparts of the infrared sources IRAS 06530-0213 and IRAS 08143-4406 were analysed.
- ID:
- ivo://CDS.VizieR/J/A+A/421/59
- Title:
- Equivalent widths of VMF73 and VMF74 galaxies
- Short Name:
- J/A+A/421/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic analysis of two galaxy clusters out to ~4Mpc at z~0.2. The two clusters VMF73 and VMF74 identified by Vikhlinin et al. (1998, Cat. <J/ApJ/502/558>) were observed with MOSCA at the Calar Alto 3.5m telescope. Both clusters lie in the ROSAT PSPC field R285 and were selected from the X-ray Dark Cluster Survey (Gilbank et al., 2004MNRAS.348..551G) that provides optical V- and I-band data. VMF73 and VMF74 are located at respective redshifts of z=0.25 and z=0.18 with velocity dispersions of 671km/s and 442km/s, respectively. The spectroscopic observations reach out to ~2.5 virial radii. Line strength measurements of the emission lines H_alpha and [OII]3727 are used to assess the star formation activity of cluster galaxies which show radial and density dependences. The mean and median of both line strength distributions as well as the fraction of star forming galaxies increase with increasing clustercentric distance and decreasing local galaxy density. Except for two galaxies with strong H_alpha and [OII] emission, all of the cluster galaxies are normal star forming or passive galaxies. Our results are consistent with other studies that show the truncation in star formation occurs far from the cluster centre.
- ID:
- ivo://CDS.VizieR/J/ApJ/819/19
- Title:
- Equivalent widths of WASP-94A and WASP-94B
- Short Name:
- J/ApJ/819/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Binary stars provide an ideal laboratory for investigating the potential effects of planet formation on stellar composition. Assuming that the stars formed in the same environment/from the same material, any compositional anomalies between binary components might indicate differences in how material was sequestered in planets, or accreted by the star in the process of planet formation. We present here a study of the elemental abundance differences between WASP-94A and B, a pair of stars that each host a hot Jupiter exoplanet. The two stars are very similar in spectral type (F8 and F9), and their ~2700AU separation suggests that their protoplanetary disks were likely not influenced by stellar interactions, but WASP-94Ab's orbit --misaligned with the host star spin axis and likely retrograde-- points toward a dynamically active formation mechanism, perhaps different from that of WASP-94Bb, which is not misaligned and has a nearly circular orbit. Based on our high-quality spectra and strictly relative abundance analysis, we detect a depletion of volatiles (~-0.02dex, on average) and enhancement of refractories (~0.01dex) in WASP-94A relative to B (standard errors are ~0.005dex). This is different from every other published case of binary host star abundances, in which either no significant abundance differences are reported or there is some degree of enhancement in all elements, including volatiles. Several scenarios that may explain the abundance trend are discussed, but none can be definitively accepted or rejected. Additional high-contrast imaging observations to search for companions that may be dynamically affecting the system, as well as a larger sample of binary host star studies, are needed to better understand the curious abundance trends we observe in WASP-94A and B.
- ID:
- ivo://CDS.VizieR/J/A+A/420/683
- Title:
- Equivalent widths of 23 wide binaries
- Short Name:
- J/A+A/420/683
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present iron abundance analysis for 23 wide binaries with main sequence components in the temperature range 4900-6300K, taken from the sample of the pairs currently included in the radial velocity planet search on going at the Telescopio Nazionale Galileo (TNG) using the high resolution spectrograph SARG. The use of a line-by-line differential analysis technique between the components of each pair allows us to reach errors of about 0.02dex in the iron content difference. Most of the pairs have abundance differences lower than 0.02dex and there are no pairs with differences larger than 0.07dex. The four cases of differences larger than 0.02dex may be spurious because of the larger error bars affecting pairs with large temperature difference, cold stars and rotating stars.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A32
- Title:
- Equivalent widths of WINGS galaxies
- Short Name:
- J/A+A/566/A32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of Equivalent Width (EW) measurements of spectra from the spectroscopic follow-up of the WIde-field Nearby Galaxy-cluster Survey (WINGS).Using the Anglo Australian Telescope (AAT) and the William Herschel Telescope (WHT), we have obtained optical spectra for about 6000 galaxies selected in fields centered on 48 local (0.04<z<0.07) X-ray selected. We apply a method we have developed to automatically measure the EW of spectral lines in a robust way even in spectra with a non optimal signal to noise. This way, we derive a spectral classification reflecting the stellar content, based on the presence and strength of the [OII] (3727) and H{delta} lines.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/3039
- Title:
- Eruptive variable protostars from VVV EW
- Short Name:
- J/MNRAS/465/3039
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a companion work (Contreras Pena et al., 2017MNRAS.465.3011C, Paper I), we detected a large population of highly variable Young Stellar Objects (YSOs) in the Vista Variables in the Via Lactea (VVV) survey, typically with class I or flat spectrum spectral energy distributions and diverse light-curve types. Here we present infrared spectra (0.9-2.5 {mu}m) of 37 of these variables, many of them observed in a bright state. The spectra confirm that 15/18 sources with eruptive light curves have signatures of a high accretion rate, either showing EXor-like emission features ({Delta}v=2 CO, Br{gamma}) and/or FUor-like features ({Delta}v=2 CO and H_2_O strongly in absorption). Similar features were seen in some long-term periodic YSOs and faders but not in dippers or short-term variables. The sample includes some dusty Mira variables (typically distinguished by smooth Mira-like light curves), two cataclysmic variables and a carbon star. In total, we have added 19 new objects to the broad class of eruptive variable YSOs with episodic accretion. Eruptive variable YSOs in our sample that were observed at bright states show higher accretion luminosities than the rest of the sample. Most of the eruptive variables differ from the established FUor and EXor subclasses, showing intermediate outburst durations and a mixture of their spectroscopic characteristics. This is in line with a small number of other recent discoveries. Since these previously atypical objects are now the majority amongst embedded members of the class, we propose a new classification for them as MNors. This term (pronounced emnor) follows V1647 Ori, the illuminating star of McNeil's Nebula.
- ID:
- ivo://CDS.VizieR/J/MNRAS/432/2112
- Title:
- Estimating gas masses from HI and CO data
- Short Name:
- J/MNRAS/432/2112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a method to estimate the total gas column density, dust-to-gas and dust-to-metal ratios of distant galaxies from rest-frame optical spectra. The technique exploits the sensitivity of certain optical lines to changes in depletion of metals on to dust grains and uses photoionization models to constrain these physical ratios along with the metallicity and dust column density. We compare our gas column density estimates with HI and CO gas mass estimates in nearby galaxies to show that we recover their total gas mass surface density to within a factor of 2 up to a total surface gas mass density of ~75M{sun}/pc^2^. Our technique is independent of the conversion factor of CO to H_2_ and we show that a metallicity-dependent X_CO_ is required to achieve good agreement between our measurements and that provided by CO and HI. However, we also show that our method cannot be reliably aperture corrected to total integrated gas mass. We calculate dust-to-gas ratios for all star-forming galaxies in the Sloan Digital Sky Survey Data Release 7 and show that the resulting dependence on metallicity agrees well with the trend inferred from modelling of the dust emission of nearby galaxies using far-IR data. We also present estimates of the variation of the dust-to-metal ratio with metallicity and show that this is poorly constrained at metallicities below 50% solar. We conclude with a study of the inventory of gas in the central regions, defined both in terms of a fixed physical radius and as a fixed fraction of the half-light radius, of ~70000 star-forming galaxies from the Sloan Digital Sky Survey. We show that their central gas content and gas depletion time are not accurately predicted by a single parameter, but in agreement with recent studies we find that a combination of the stellar mass and some measure of central concentration provides a good predictor of gas content in galaxies. We also identify a population of galaxies with low surface densities of stars and very long gas depletion times.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A122
- Title:
- eta Carinae's 2014.6 spectroscopic event
- Short Name:
- J/A+A/578/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Every 5.5-years, {eta} Car's light curve and spectrum change remarkably across all observed wavelength bands. These so-called spectroscopic events are most likely caused by the close approach of a companion. We compare the recent spectroscopic event in mid-2014 to the events in 2003 and 2009 and investigate long-term trends. Eta Car was observed with HST STIS, VLT UVES, and CTIO 1.5m CHIRON for a period of more than two years in 2012-2015. Archival observations with these instruments cover three orbital cycles and the events of 2003.5, 2009.1, and 2014.6. The STIS spectra provide high spatial resolution and include epochs during the 2014 event when observations from most ground-based observatories were not feasible. The strategy for UVES observations allows for a multidimensional analysis, because each location in the reflection nebula is correlated with a different stellar latitude. Important spectroscopic diagnostics during {eta} Car's events show significant changes in 2014 compared to previous events. While the timing of the first HeII {lambda}4686 flash was remarkably similar to previous events, the HeII equivalent widths were slightly larger, and the line flux increased by a factor of ~7 compared to 2003. The second HeII peak occurred at about the same phase as in 2009, but was stronger. The HeI line flux grew by a factor of ~8 in 2009-2014 compared to 1998-2003. The NII emission lines also increased in strength. On the other hand, H{alpha} and FeII lines show the smallest emission strengths ever observed in {eta} Car. The optical continuum brightened by a factor of ~4 in the past 10-15 years. The polar spectrum shows fewer changes in the broad wind emission lines: the FeII emission strength decreased by a factor of ~2 (compared to a factor of ~4 in our direct line of sight). The HeII equivalent widths at FOS4 were larger in 2009 and 2014 than during the 2003 event.
