- ID:
- ivo://CDS.VizieR/J/A+A/641/A127
- Title:
- 13 dsph and ultra-faint galaxies analysis
- Short Name:
- J/A+A/641/A127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a large homogeneous set of stellar parameters and abundances across a broad range of metallicities, involving 13 classical dwarf spheroidal (dSph) and ultra-faint dSph (UFD) galaxies. In total, this study includes 380 stars in Fornax, Sagittarius, Sculptor, Sextans, Carina, Ursa Minor, Draco, Reticulum II, Bootes I, Ursa Major II, Leo I, Segue I, and Triangulum II. This sample represents the largest, homogeneous, high-resolution study of dSph galaxies to date. With our homogeneously derived catalog, we are able to search for similar and deviating trends across different galaxies. We investigate the mass dependence of the individual systems on the production of alpha-elements, but also try to shed light on the long-standing puzzle of the dominant production site of r-process elements. We used data from the Keck observatory archive and the ESO reduced archive to reanalyze stars from these 13 classical dSph and UFD galaxies. We automatized the step of obtaining stellar parameters, but ran a full spectrum synthesis (1D, local thermal equilibrium) to derive all abundances except for iron to which we applied nonlocal thermodynamic equilibrium corrections where possible. The homogenized set of abundances yielded the unique possibility of deriving a relation between the onset of type Ia supernovae and the stellar mass of the galaxy. Furthermore, we derived a formula to estimate the evolution of alpha-elements. This reveals a universal relation of these systems across a large range in mass. Finally, we show that between stellar masses of 2.1x10^7^M_{sun}_ and 2.9x10^5^M_{sun}_ , there is no dependence of the production of heavy r-process elements on the stellar mass of the galaxy. Placing all abundances consistently on the same scale is crucial to answering questions about the chemical history of galaxies. By homogeneously analyzing Ba and Eu in the 13 systems, we have traced the onset of the s-process and found it to increase with metallicity as a function of the galaxy's stellar mass. Moreover, the r-process material correlates with the alpha-elements indicating some coproduction of these, which in turn would point toward rare core-collapse supernovae rather than binary neutron star mergers as a host for the r-process at low [Fe/H] in the investigated dSph systems.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/606/A71
- Title:
- dSph RGB abundance and velocities
- Short Name:
- J/A+A/606/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From ESO VLT/FLAMES/GIRAFFE spectra, abundance measurements of Zn have been made in ~100 individual red giant branch (RGB) stars in the Sculptor dwarf spheroidal galaxy. This is the largest sample of individual Zn abundance measurements within a stellar system beyond the Milky Way. In the observed metallicity range, -2.7<=[Fe/H]<=-0.9, the general trend of Zn abundances in Sculptor is similar to that of {alpha}-elements. That is, super-solar abundance ratios of [Zn/Fe] at low metallicities, which decrease with increasing [Fe/H], eventually reaching subsolar values. However, at the higher metallicities in Sculptor, [Fe/H]>~-1.8, we find a significant scatter, -0.8<~[Zn/Fe]<~+0.4, which is not seen in any {alpha}-element. Our results are consistent with previous observations of a limited number of stars in Sculptor and in other dwarf galaxies. These results suggest that zinc has a complex nucleosynthetic origin, behaving neither completely like an {alpha}- nor an iron-peak element.
- ID:
- ivo://CDS.VizieR/J/ApJ/779/7
- Title:
- dSph satellites of M31. I. Variables in And XIX
- Short Name:
- J/ApJ/779/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present B, V time-series photometry of Andromeda XIX (And XIX), the most extended (half-light radius of 6.2') of Andromeda's dwarf spheroidal companions, which we observed with the Large Binocular Cameras at the Large Binocular Telescope. We surveyed a 23'x23' area centered on And XIX and present the deepest color-magnitude diagram (CMD) ever obtained for this galaxy, reaching, at V~26.3mag, about one magnitude below the horizontal branch (HB). The CMD shows a prominent and slightly widened red giant branch, along with a predominantly red HB, which extends to the blue to significantly populate the classical instability strip. We have identified 39 pulsating variable stars, of which 31 are of RR Lyrae type and 8 are Anomalous Cepheids (ACs). Twelve of the RR Lyrae variables and three of the ACs are located within And XIX's half light radius. The average period of the fundamental mode RR Lyrae stars (<P_ab_>{=}0.62days, {sigma}=0.03days) and the period-amplitude diagram qualify And XIX as an Oosterhoff-Intermediate system. From the average luminosity of the RR Lyrae stars (<V(RR)>=25.34mag, {sigma}=0.10mag), we determine a distance modulus of (m-M)_0_=24.52+/-0.23mag in a scale where the distance to the Large Magellanic Cloud (LMC) is 18.5+/-0.1mag. The ACs follow a well-defined Period-Wesenheit (PW) relation that appears to be in very good agreement with the PW relationship defined by the ACs in the LMC.
- ID:
- ivo://CDS.VizieR/J/AJ/150/151
- Title:
- DSSI observations of binaries. VI. Measures in 2014
- Short Name:
- J/AJ/150/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of 938 speckle measures of double stars and suspected double stars drawn mainly from the Hipparcos Catalog, as well as 208 observations where no companion was noted. One hundred fourteen pairs have been resolved for the first time. The data were obtained during four observing runs in 2014 using the Differential Speckle Survey Instrument at Lowell Observatory's Discovery Channel Telescope. The measurement precision obtained when comparing to ephemeris positions of binaries with very well-known orbits is generally less than 2mas in separation and 0.5{deg} in position angle. Differential photometry is found to have internal precision of approximately 0.1mag and to be in very good agreement with Hipparcos measures in cases where the comparison is most relevant. We also estimate the detection limit in the cases where no companion was found. Visual orbital elements are derived for six systems.
- ID:
- ivo://CDS.VizieR/J/AJ/157/56
- Title:
- DSSI observations of binary & trinary star systems
- Short Name:
- J/AJ/157/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 248 speckle observations of 43 binary and 19 trinary star systems chosen to make progress in two main areas of investigation: the fundamental properties of metal-poor stars and star formation mechanisms. The observations were taken at the Gemini North and South telescopes during the period 2015 July to 2018 April, mainly with the Differential Speckle Survey Instrument but also with a few early results from the new 'Alopeke speckle camera at Gemini North. We find that the astrometry and photometry of these observations as a whole are consistent with previous work at Gemini. We present five new visual orbits for systems important in understanding metal-poor stars, three of which have orbital periods of less than 4 yr, and we indicate the degree to which these and future observations can impact our knowledge of stellar properties and star formation. In particular, we find a decrease in mass at fixed spectral type for metal-poor stars versus their solar-metallicity analogs that is consistent with predictions that are made from current stellar models.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/208
- Title:
- 2D stellar kinematics of Mrk 1216
- Short Name:
- J/ApJ/835/208
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mrk 1216 is a nearby, early-type galaxy with a small effective radius of 2.8kpc and a large stellar velocity dispersion of 308km/s for its K-band luminosity of 1.4x10^11^L_{sun}_. Using integral field spectroscopy assisted by adaptive optics from Gemini North, we measure spatially resolved stellar kinematics within ~450pc of the galaxy nucleus. The galaxy exhibits regular rotation with velocities of +/-180km/s and a sharply peaked velocity dispersion profile that reaches 425km/s at the center. We fit axisymmetric, orbit-based dynamical models to the combination of these high angular resolution kinematics, large-scale kinematics extending to roughly three effective radii, and Hubble Space Telescope imaging, resulting in a constraint of the mass of the central black hole in Mrk 1216. After exploring several possible sources of systematics that commonly affect stellar-dynamical black hole mass measurements, we find a black hole mass of M_BH_=(4.9+/-1.7)x10^9^M_{sun}_ and an H-band stellar mass-to-light ratio of {Upsilon}_H_=1.3+/-0.4{Upsilon}_{sun}_ (1{sigma} uncertainties). Mrk 1216 is consistent with the local black hole mass-stellar velocity dispersion relation, but is a factor of ~5-10 larger than expectations from the black hole mass-bulge luminosity and black hole mass-bulge mass correlations when conservatively using the galaxy's total luminosity or stellar mass. This behavior is quite similar to the extensively studied compact galaxy NGC 1277. Resembling the z~2 quiescent galaxies, Mrk 1216 may be a passively evolved descendant, and perhaps reflects a previous era when galaxies contained over-massive black holes relative to their bulge luminosities/masses, and the growth of host galaxies had yet to catch up.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A66
- Title:
- DS Tuc A radial velocity curve
- Short Name:
- J/A+A/650/A66
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The observations of young close-in exoplanets are providing first indications of the characteristics of the population and, in turn, clues on the early stages of their evolution. Transiting planets at young ages are also key benchmarks for our understanding of planetary evolution through the verification of atmospheric escape models. We performed a radial velocity (RV) monitoring of the 40Myr old star DS Tuc A with HARPS at the ESO-3.6m to determine the planetary mass of its 8.14-days planet, first revealed by the NASA TESS satellite. We also observed two planetary transits with HARPS and ESPRESSO at ESO-VLT, to measure the Rossiter-McLaughlin (RM) effect and characterise the planetary atmosphere. We measured the high-energy emission of the host with XMM-Newton observations to investigate models for atmospheric evaporation. We employed Gaussian Processes (GP) regression to model the high level of the stellar activity, which is more than 40 times larger than the expected RV planetary signal. GPs were also used to correct the stellar contribution to the RV signal of the RM effect. We extracted the transmission spectrum of DS Tuc A b from the ESPRESSO data and searched for atmospheric elements/molecules either by single-line retrieval and by performing cross-correlation with a set of theoretical templates. Through a set of simulations, we evaluated different scenarios for the atmospheric photo-evaporation of the planet induced by the strong XUV stellar irradiation. While the stellar activity prevented us from obtaining a clear detection of the planetary signal from the RVs, we set a robust mass upper limit of 14.4Me for DS Tuc A b. We also confirm that the planetary system is almost (but not perfectly) aligned. The strong level of stellar activity hampers the detection of any atmospheric compounds, in line with other studies presented in the literature. The expected evolution of DS Tuc A b from our grid of models indicates that the planetary radius after the photo-evaporation phase will be 1.8-2.0Re, falling within the Fulton gap. The comparison of the available parameters of known young transiting planets with the distribution of their mature counterpart confirms that the former are characterised by a low density, with DS Tuc A b being one of the less dense. A clear determination of their distribution is still affected by the lack of a robust mass measurement, in particular for planets younger than ~100Myr.
- ID:
- ivo://CDS.VizieR/J/A+A/333/658
- Title:
- D-type symbiotic stars emission line fluxes
- Short Name:
- J/A+A/333/658
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of five D-type symbiotics are presented: three oxygen Mira (He2-38, H2-38 and H1-36) and two carbon Mira symbiotics (AS 210 and SS 38). The observations in the spectral range between 3200{AA} and 7400{AA} show the presence of several emission lines in various states of excitation. A line list is provided with their suggested identifications. Several parameters were derived for each object: interstellar reddening as determined from Balmer decrement and He II lines, temperature and electronic density, abundance ratios of Ne/O, Ar/O, Fe/Ne, N/O and He/H. We found nitrogen enrichment while for the other elements their abundances are compatible with solar, except iron which is depleted. We did not detect significant changes in the line and in the continuos spectra of the stars analyzed here, except for He2-38, which increased its degree of excitation compared to Allen's (1984PASAu...5..562N) catalogue.
- ID:
- ivo://CDS.VizieR/J/ApJ/746/L22
- Title:
- Dual AGNs in the nearby Universe
- Short Name:
- J/ApJ/746/L22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the fraction of dual active galactic nuclei (AGNs) in a sample of 167 nearby (z < 0.05), moderate-luminosity, ultra-hard X-ray-selected AGNs from the all-sky Swift Burst Alert Telescope (BAT) survey. Combining new Chandra and Gemini observations together with optical and X-ray observations, we find that the dual AGN frequency at scales <100 kpc is ~10% (16/167). Of the 16 dual AGNs, only 3 (19%) were detected using X-ray spectroscopy and were not detected using emission line diagnostics. Close dual AGNs (<30 kpc) tend to be more common among the most X-ray luminous systems. In dual AGNs, the X-ray luminosity of both AGNs increases strongly with decreasing galaxy separation, suggesting that the merging event is key in powering both AGNs. Fifty percent of the AGNs with a very close companion (<15 kpc) are dual AGNs. We also find that dual AGNs are more likely to occur in major mergers and tend to avoid absorption line galaxies with elliptical morphologies. Finally, we find that SDSS Seyferts are much less likely than BAT AGNs (0.25% versus 7.8%) to be found in dual AGNs at scales <30 kpc because of a smaller number of companion galaxies, fiber collision limits, a tendency for AGNs at small separations to be detected only in X-rays, and a higher fraction of dual AGN companions with increasing AGN luminosity.
- ID:
- ivo://CDS.VizieR/J/A+AS/95/1
- Title:
- Dumb-bell galaxies in Southern Rich Clusters
- Short Name:
- J/A+AS/95/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)