- ID:
- ivo://CDS.VizieR/J/ApJ/725/1252
- Title:
- Confirmed members of RX J0152.7-1357
- Short Name:
- J/ApJ/725/1252
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectrophotometric analysis of galaxies belonging to the dynamically young, massive cluster RX J0152.7-1357 at z~0.84, aimed at understanding the effects of the cluster environment on the star formation history (SFH) of cluster galaxies and the assembly of the red sequence (RS). We use VLT/FORS spectroscopy, ACS/WFC optical, and NTT/SofI near-IR data to characterize SFHs as a function of color, luminosity, morphology, stellar mass, and local environment from a sample of 134 spectroscopic members. In order to increase the signal-to-noise ratio, individual galaxy spectra are stacked according to these properties. Moreover, the D4000, Balmer, CN3883, Fe4383, and C4668 indices are also quantified.
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- ID:
- ivo://CDS.VizieR/J/A+A/608/A46
- Title:
- Constraining cosmic scatter
- Short Name:
- J/A+A/608/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the stellar parameters, abundances, associated errors and the linelist of a set of 23 metal-poor and very metal-poor halo stars. Stellar parameters and chemical abundances were derived in a line-by-line differential analysis from equivalent widths of UVES/VLT spectra. The differential analysis provided us unprecedented small data scatter and errors. Our sample, along with data from different authors in different metallicity ranges, allowed us to do an extensive comparison of the chemical abundances with the predictions of a Galaxy chemical evolution model.
- ID:
- ivo://CDS.VizieR/J/ApJ/866/133
- Title:
- Continuum-H{beta} light curves of 5 Seyfert 1
- Short Name:
- J/ApJ/866/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from a reverberation-mapping campaign undertaken during the first half of 2012, with additional data on one active galactic nucleus (AGN) (NGC 3227) from a 2014 campaign. Our main goals are (1) to determine the black hole masses from continuum-H{beta} reverberation signatures, and (2) to look for velocity-dependent time delays that might be indicators of the gross kinematics of the broad-line region. We successfully measure H{beta} time delays and black hole masses for five AGNs, four of which have previous reverberation mass measurements. The values measured here are in agreement with earlier estimates, though there is some intrinsic scatter beyond the formal measurement errors. We observe velocity-dependent H{beta} lags in each case, and find that the patterns have changed in the intervening five years for three AGNs that were also observed in 2007.
- ID:
- ivo://CDS.VizieR/J/A+A/654/A168
- Title:
- Convective blueshifts for solar-type stars
- Short Name:
- J/A+A/654/A168
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The detection of earth-mass exoplanets in the habitable zone around solar-mass stars using the radial velocity technique requires extremely high- precision of the order of 10cm/s. This puts the required noise floor below the intrinsic variability of even relatively inactive stars, like the Sun. One such variable is convective blueshift varying temporally, spatially and between spectral lines. We develop a novel approach to measure convective blueshift and determine the strength of convective blueshift for 810 stars observed by the HARPS spectrograph, spanning spectral types from late-F, G, K to early-M. We derive a model to infer blueshift velocity for lines of any depth in later-type stars of any effective temperature. Using a custom list of spectral lines, covering a wide range of absorption depths, we create a model for the line-core shift as a function of line depth, commonly known as the third signature of granulation. For this we utilize an extremely high-resolution solar spectrum (R~1.000.000) to empirically account for the non-linear nature of the third signature. The solar third signature is then scaled to all 810 stars. Through this we obtain a measure of the convective blueshift relative to the Sun as a function of stellar effective temperature. We confirm the general correlation of increasing convective blueshift with effective temperature and establish a tight, cubic relation between the two that strongly increases for stars above ~5800K. For stars between ~4100K and ~4700K we show for the first time a plateau in convective shift and a possible onset of a plateau for stars above 6000K. Stars below ~4000K show neither blue or red shift. We provide a table listing expected blueshift velocities for each spectral subtype in the data set to quickly access the intrinsic noise floor through convective blueshift for the RV technique.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A57
- Title:
- Convective blueshifts in solar atmos.
- Short Name:
- J/A+A/624/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Convective motions in the solar atmosphere cause spectral lines to become asymmetric and shifted in wavelength. For photospheric lines, this differential Doppler shift varies from the solar disk center to the limb. Precise and comprehensive observations of the convective blueshift and its center-to-limb variation improve our understanding of the atmospheric hydrodynamics and ensuing line formation, and provide the basis to refine 3D models of the solar atmosphere. We performed systematical spectroscopic measurements of the convective blueshift of the quiet Sun with the Laser Absolute Reference Spectrograph (LARS) at the German Vacuum Tower Telescope. The spatial scanning of the solar disk covered 11 heliocentric positions each along four radial (meridional and equatorial) axes. The high-resolution spectra of 26 photospheric to chromospheric lines in the visible range were calibrated with a laser frequency comb to absolute wavelengths at the 1m/s accuracy. Applying ephemeris and reference corrections, the bisector analysis provided line asymmetries and Doppler shifts with an uncertainty of only few m/s. To allow for a comparison with other observations, we convolved the results to lower spectral resolutions.
- ID:
- ivo://CDS.VizieR/J/A+A/554/A11
- Title:
- CO observations of polar ring galaxies
- Short Name:
- J/A+A/554/A11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have searched for CO lines in a sample of 21 new morphologically determined polar ring galaxies (of which 9 are kinematically confirmed), obtained from a wide search in the Galaxy Zoo project by Moiseev and collaborators. Polar ring galaxies (PRG) are a unique class of objects, tracing special episodes in the galaxy mass assembly: they could be formed through galaxy interaction, merging, but also through accretion from cosmic filaments. Beside, they enable the study of dark matter haloes in 3 dimensions. The polar ring itself is a sub-system rich in gas, where molecular gas is expected, and new stars are formed. Among the sample of 21 PRG, we have detected five CO-rich systems, that can now be followed up with higher spatial resolution. Their average molecular mass is 9.4x10^9^M_{sun}_, and their average gas fraction is 27% of their baryonic mass, with a range from 15 to 43%, implying that they just accreted a large amount of gas. The position of the detected objects in the velocity- magnitude diagram is offset from the Tully-Fisher relation of normal spirals, as was already found for PRG. This work is part of our multi-wavelength project to determine the detailed morphology and dynamics of Polar-Ring galaxies, test through numerical models their formation scenario, and deduce their dark matter content and 3D-shape.
- ID:
- ivo://CDS.VizieR/J/AJ/158/87
- Title:
- 86 cool dwarfs observed during K2 Campaigns 1-17
- Short Name:
- J/AJ/158/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present revised stellar properties for 172 K2 target stars that were identified as possible hosts of transiting planets during Campaigns 1-17. Using medium-resolution near-infrared spectra acquired with the NASA Infrared Telescope Facility/SpeX and Palomar/TripleSpec, we found that 86 of our targets were bona fide cool dwarfs, 74 were hotter dwarfs, and 12 were giants. Combining our spectroscopic metallicities with Gaia parallaxes and archival photometry, we derived photometric stellar parameters and compared them to our spectroscopic estimates. Although our spectroscopic and photometric radius and temperature estimates are consistent, our photometric mass estimates are systematically {Delta}M_*_=0.11 M_{sun}_ (34%) higher than our spectroscopic mass estimates for the least massive stars (M_*,phot_<0.4 M_{sun}_). Adopting the photometric parameters and comparing our results to parameters reported in the Ecliptic Plane Input Catalog, our revised stellar radii are {Delta}R_*_=0.15 R_{sun}_ (40%) larger, and our revised stellar effective temperatures are roughly {Delta}T_eff_=65 K cooler. Correctly determining the properties of K2 target stars is essential for characterizing any associated planet candidates, estimating the planet search sensitivity, and calculating planet occurrence rates. Even though Gaia parallaxes have increased the power of photometric surveys, spectroscopic characterization remains essential for determining stellar metallicities and investigating correlations between stellar metallicity and planetary properties.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A143
- Title:
- Cool, evolved stars PACS and SPIRE spectroscopy
- Short Name:
- J/A+A/618/A143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- At the end of their lives AGB stars are prolific producers of dust and gas. The details of this mass-loss process are still not understood very well. Herschel PACS and SPIRE spectra which cover the wavelength range from ~55 to 670um almost continuously, offer a unique way of investigating properties of AGB stars in general and the mass-loss process in particular as this is the wavelength region where dust emission is prominent and molecules have many emission lines. We present the community with a catalogue of AGB stars and red supergiants (RSGs) with PACS and/or SPIRE spectra reduced according to the current state of the art. The Herschel Interactive Processing Environment (HIPE) software with the latest calibration is used to process the available PACS and SPIRE spectra of 40 evolved stars. The SPIRE spectra of some objects close to the Galactic plane require special treatment because of the weaker fluxes in combination with the strong and complex background emission at those wavelengths. The spectra are convolved with the response curves of the PACS and SPIRE bolometers and compared to the fluxes measured in imaging data of these sources. Custom software is used to identify lines in the spectra, and to determine the central wavelengths and line intensities. Standard molecular line databases are used to associate the observed lines. Because of the limited spectral resolution of the PACS and SPIRE spectrometers (~1500), several known lines are typically potential counterparts to any observed line. To help identifications in follow-up studies the relative contributions in line intensity of the potential counterpart lines are listed for three characteristic temperatures based on local thermodynamic equilibrium (LTE) calculations and assuming optically thin emission. The following data products are released: the reduced spectra, the lines that are measured in the spectra with wavelength, intensity, potential identifications, and the continuum spectra, i.e. the full spectra with all identified lines removed. As simple examples of how this data can be used in future studies we have fitted the continuum spectra with three power laws (two wavelength regimes covering PACS, and one covering SPIRE) and find that the few OH/IR stars seem to have significantly steeper slopes than the other oxygen- and carbon-rich objects in the sample, possibly related to a recent increase in mass-loss rate. As another example we constructed rotational diagrams for CO (and HCN for the carbon stars) and fitted a two-component model to derive rotational temperatures.
- ID:
- ivo://CDS.VizieR/J/ApJS/213/5
- Title:
- Cool KOIs. VI. H- and K- band spectra
- Short Name:
- J/ApJS/213/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present H- and K-band spectra for late-type Kepler Objects of Interest (the "Cool KOIs"): low-mass stars with transiting-planet candidates discovered by NASA's Kepler Mission that are listed on the NASA Exoplanet Archive. We acquired spectra of 103 Cool KOIs and used the indices and calibrations of Rojas-Ayala et al. (2012, Cat. J/ApJ/748/93) to determine their spectral types, stellar effective temperatures, and metallicities, significantly augmenting previously published values. We interpolate our measured effective temperatures and metallicities onto evolutionary isochrones to determine stellar masses, radii, luminosities, and distances, assuming the stars have settled onto the main sequence. As a choice of isochrones, we use a new suite of Dartmouth predictions that reliably include mid-to-late M dwarf stars. We identify five M4V stars: KOI-961 (confirmed as Kepler 42), KOI-2704, KOI-2842, KOI-4290, and the secondary component to visual binary KOI-1725, which we call KOI-1725B. We also identify a peculiar star, KOI-3497, which has Na and Ca lines consistent with a dwarf star but CO lines consistent with a giant. Visible-wavelength adaptive optics imaging reveals two objects within a 1 arcsec diameter; however, the objects' colors are peculiar. The spectra and properties presented in this paper serve as a resource for prioritizing follow-up observations and planet validation efforts for the Cool KOIs.
- ID:
- ivo://CDS.VizieR/J/A+A/616/A108
- Title:
- Cool stars chromospheric activity catalog
- Short Name:
- J/A+A/616/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chromospheric activity monitoring of a wide range of cool stars can provide valuable information on stellar magnetic activity and its dependence on fundamental stellar parameters such as effective temperature and rotation. We compile a chromospheric activity catalogue of 4454 cool stars from a combination of archival HARPS spectra and multiple other surveys, including the Mount Wilson data that have recently been released by the NSO. We explore the variation in chromospheric activity of cool stars along the main sequence for stars with different effective temperatures. Additionally, we also perform an activity-cycle period search and investigate its relation with rotation. The chromospheric activity index, S-index, was measured for 304 main-sequence stars from archived high-resolution HARPS spectra. Additionally, the measured and archived S-indices were converted into the chromospheric flux ratio logR'HK. The activity-cycle periods were determined using the generalised Lomb-Scargle periodogram to study the active and inactive branches on the rotation-activity-cycle period plane. The global sample shows that the bimodality of chromospheric activity, known as the Vaughan-Preston gap, is not prominent, with a significant percentage of the stars at an intermediate-activity level around logR'HK=-4.75. Independently, the cycle period search shows that stars can lie in the region intermediate between the active and inactive branch, which means that the active branch is not as clearly distinct as previously thought. The weakening of the Vaughan-Preston gap indicates that cool stars spin down from a higher activity level and settle at a lower activity level without a sudden break at intermediate activity. Some cycle periods are close to the solar value between the active and inactive branch, which suggests that the solar dynamo is most likely a common case of the stellar dynamo.
