- ID:
- ivo://CDS.VizieR/J/ApJ/860/109
- Title:
- Keck HIRES obs. of 245 subgiants (retired A stars)
- Short Name:
- J/ApJ/860/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exoplanet surveys of evolved stars have provided increasing evidence that the formation of giant planets depends not only on stellar metallicity ([Fe/H]) but also on the mass (M*). However, measuring accurate masses for subgiants and giants is far more challenging than it is for their main-sequence counterparts, which has led to recent concerns regarding the veracity of the correlation between stellar mass and planet occurrence. In order to address these concerns, we use HIRES spectra to perform a spectroscopic analysis on a sample of 245 subgiants and derive new atmospheric and physical parameters. We also calculate the space velocities of this sample in a homogeneous manner for the first time. When reddening corrections are considered in the calculations of stellar masses and a -0.12M_{sun}_ offset is applied to the results, the masses of the subgiants are consistent with their space velocity distributions, contrary to claims in the literature. Similarly, our measurements of their rotational velocities provide additional confirmation that the masses of subgiants with M*>=1.6M_{sun}_ (the "retired A stars") have not been overestimated in previous analyses. Using these new results for our sample of evolved stars, together with an updated sample of FGKM dwarfs, we confirm that giant planet occurrence increases with both stellar mass and metallicity up to 2.0M_{sun}_. We show that the probability of formation of a giant planet is approximately a one-to-one function of the total amount of metals in the protoplanetary disk M* 10^[Fe/H]. This correlation provides additional support for the core accretion mechanism of planet formation.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/869/123
- Title:
- Keck Lyman continuum spectroscopic survey (KLCS)
- Short Name:
- J/ApJ/869/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a deep spectroscopic survey quantifying the statistics of the escape of ionizing radiation from star-forming galaxies at z~3. We measure the ratio of ionizing to non-ionizing UV flux density <f_900_/f_1500_>_obs_, where f_900_ is the mean flux density evaluated over the range [880,910]{AA}. We quantify the emergent ratio of ionizing to non-ionizing UV flux density by analyzing high signal-to-noise ratio composite spectra formed from subsamples with common observed properties and numbers sufficient to reduce the statistical uncertainty in the modeled IGM+CGM correction to obtain precise values of <f_900_/f_1500_>_out_, including a full-sample average <f_900_/f_1500>_out_=0.057{+/-}0.006. We show that <f_900_/f_1500_>_out_ increases monotonically with W_{lambda}_(Ly{alpha}), inducing an inverse correlation with UV luminosity as a by-product. We fit the composite spectra using stellar spectral synthesis together with models of the ISM in which a fraction f_c_ of the stellar continuum is covered by gas with column density N_HI_. We show that the composite spectra simultaneously constrain the intrinsic properties of the stars (L_900_/L_1500_)_int_ along with f_c_, N_HI_, E(B-V), and f_esc,abs_, the absolute escape fraction of ionizing photons. We find a sample-averaged f_esc,abs_=0.09{+/-}0.01, with subsamples falling along a linear relation <f_esc,abs_>~0.75[W_{lambda}_(Ly{alpha})/110{AA}]. Using the far-UV luminosity function, the distribution function n(W(Ly{alpha})), and the relationship between W_{lambda}_(Ly{alpha}) and <f_900_/f_1500_>_out_, we estimate the total ionizing emissivity of z~3 star-forming galaxies with M_uv_<=-19.5, which exceeds the contribution of quasi-stellar objects by a factor of ~3, and accounts for ~50% of the total {epsilon}LyC at z~3 estimated using indirect methods.
- ID:
- ivo://CDS.VizieR/J/MNRAS/494/2429
- Title:
- Kinematics of nearby young stars
- Short Name:
- J/MNRAS/494/2429
- Date:
- 19 Nov 2021 14:22:11
- Publisher:
- CDS
- Description:
- In the last three decades several hundred nearby members of young stellar moving groups (MGs) have been identified, but there has been less systematic effort to quantify or characterize young stars that do not belong to previously identified MGs. Using a kinematically unbiased sample of 225 lithium-rich stars within 100 pc, we find that only 50+/-10 per cent of young (<=125Myr), low-mass (0.5<M/M_{sun}_<1.0) stars, are kinematically associated with known MGs. Whilst we find some evidence that five of the non-MG stars may be connected with the Lower Centaurus-Crux association, the rest form a kinematically 'hotter' population, much more broadly dispersed in velocity, and with no obvious concentrations in space. The mass distributions of the MG members and non-MG stars are similar, but the non-MG stars may be older on average. We briefly discuss several explanations for the origin of the non-MG population.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A94
- Title:
- Kinematics of the Gamma Vel cluster
- Short Name:
- J/A+A/563/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A key science goal of the Gaia-ESO survey (GES) at the VLT is to use the kinematics of low-mass stars in young clusters and star forming regions to probe their dynamical histories and how they populate the field as they become unbound. The clustering of low-mass stars around the massive Wolf-Rayet binary system {gamma}^2^ Velorum was one of the first GES targets. Targets were selected from colour-magnitude diagrams and intermediate resolution spectroscopy was used to derive radial velocities and assess membership from the strength of the LiI 6708{AA} line. The radial velocity distribution was analysed using a maximum likelihood technique that accounts for unresolved binaries.
- ID:
- ivo://CDS.VizieR/J/AJ/130/496
- Title:
- KISS emission-line galaxy candidates
- Short Name:
- J/AJ/130/496
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic observations for 315 emission-line galaxy (ELG) candidates from the KPNO International Spectroscopic Survey (KISS) have been obtained using the MDM Observatory 2.4m telescope on Kitt Peak. KISS is a wide-field objective-prism survey for extragalactic emission-line objects that has cataloged over 2200 ELG candidates to date. Spectroscopic follow-up observations are being carried out to study the characteristics of the survey objects. The observational data presented here include redshifts, reddening estimates, line equivalent widths, H{alpha} line fluxes, and emission-line ratios. The galaxies have been classified based on their emission-line characteristics.
- ID:
- ivo://CDS.VizieR/J/AJ/130/2584
- Title:
- KISS emission-line galaxy candidates. IV
- Short Name:
- J/AJ/130/2584
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic observations for 614 emission-line galaxy (ELG) candidates from the KPNO International Spectroscopic Survey (KISS) have been obtained using the KPNO 2.1m telescope and the WIYN 3.5m telescope. KISS is a wide-field objective-prism survey for extragalactic emission-line objects that has cataloged over 2400 ELG candidates to date. Spectroscopic follow-up observations are being carried out at several telescopes to study the characteristics of the survey objects. We present the following data derived from the KPNO spectra: redshifts, reddening estimates, line equivalent widths, H{alpha} line fluxes, and emission-line ratios. The galaxies have been classified based on their emission-line characteristics.
- ID:
- ivo://CDS.VizieR/J/AJ/130/2571
- Title:
- KISS H{alpha}-selected survey list 3
- Short Name:
- J/AJ/130/2571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The KPNO International Spectroscopic Survey (KISS) is an objective-prism survey designed to detect extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys with the advantages of modern CCD detectors and is the first purely digital objective-prism survey for emission-line galaxies (ELGs). Here we present the third list of ELG candidates selected from our red spectral data, which cover the wavelength range 6400-7200{AA}. In most cases, the detected emission line is H{alpha}. The current survey list covers the region of the NOAO Deep Wide Field Survey (NDWFS). This survey covers two fields; the first is 3{deg}x3{deg} and located at RA=14h30m, DE=34{deg}30' (B1950.0), and the second is 2.3{deg}x4.0{deg} and centered at RA=2h7m30s, DE=-4{deg}44'. A total area of 19.65deg^2^ is covered by the KISS data. A total of 261 candidate emission-line objects have been selected for inclusion in the survey list (13.3deg^-2^). We tabulate accurate coordinates and photometry for each source, as well as estimates of the redshift, emission-line flux, and line equivalent width based on measurements of the digital objective-prism spectra. The properties of the KISS ELGs are examined using the available observational data.
- ID:
- ivo://CDS.VizieR/J/AJ/121/66
- Title:
- KISS H{alpha} survey list 1
- Short Name:
- J/AJ/121/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The KPNO International Spectroscopic Survey (KISS) is a new objective-prism survey for extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys with the advantages of modern CCD detectors and is the first purely digital objective-prism survey for emission-line galaxies. Here we present the first list of emission-line galaxy candidates selected from our red spectral data, which cover the spectral range 6400 to 7200{AA}. In most cases, the detected emission line is H{alpha}. The current survey list covers a 1{deg}-wide strip located at {delta}= 29{deg} 30' (B1950.0) and spanning the right ascension range 12h 15m to 17h 0m. An area of 62.2{deg}^2^ is covered. A total of 1128 candidate emission-line objects have been selected for inclusion in the survey list (18.1{deg}^-2^). We tabulate accurate coordinates and photometry for each source, as well as estimates of the redshift and emission-line flux and equivalent width based on measurements of the digital objective-prism spectra. The properties of the KISS emission-line galaxies are examined using the available observational data.
- ID:
- ivo://CDS.VizieR/J/AJ/123/1292
- Title:
- KISS III. [O III]-selected survey list
- Short Name:
- J/AJ/123/1292
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The KPNO International Spectroscopic Survey (KISS) is an objective-prism survey for extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys with the advantages of modern CCD detectors, and it is the first purely digital objective-prism survey for emission-line galaxies. Here we present the first list of emission-line galaxy candidates selected from our blue spectral data, which cover the wavelength range 4800-5500{AA}. In most cases, the detected emission line is [O III] {lambda}5007. The current survey list covers a 1{deg}-wide strip located at {delta}=29{deg}30' (B1950.0) and spanning the right ascension range 8h30min to 17h0min. An area of 116.6d{deg}^2^ is covered. A total of 223 candidate emission-line objects have been selected for inclusion in the survey list (1.91{deg}^-2^). We tabulate accurate coordinates and photometry for each source, as well as estimates of the redshift, emission-line flux, and equivalent width based on measurements of the digital objective-prism spectra. The median apparent magnitude of the sample is B=18.2, and galaxies with redshifts approaching z=0.1 are detected.
- ID:
- ivo://CDS.VizieR/J/A+A/328/175
- Title:
- K & M giants equivalent widths
- Short Name:
- J/A+A/328/175
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analyses of high resolution infrared spectra have been done for CN lines in oxygen-rich cool evolved stars including 2 K giants, 20 M giants and 1 S-type star. Since CN lines analyzed in the present work are weak and resolved well, they are appropriate for quantitative analyses. CN lines of {DELTA}v=-2 and -1 sequences (red system) which are in the K- and the H-window regions, respectively, give the consistent nitrogen abundance for each star. The analyses of NH lines in the L-window region have been done for 5 late M giants for which CN lines have been also analyzed. Although the triplet structure of NH lines cannot be fully resolved, they are preferable because determination of nitrogen abundance is almost independent of other elemental abundances while nitrogen abundance based on CN depends on carbon abundance. The nitrogen abundances derived from NH for late M giants agree well with those from CN for which we adopt 7.75eV as the dissociation energy in the analysis. The results show that the nitrogen abundances in late M giants are larger than those in early M giants while decrease of the carbon abundance was found in late M giants by our previous work (Tsuji, 1991A&A...245..203T). These variations of abundances can not be explained by the first dredge-up model but require additional processing by the CN cycle and mixing after the first dredge-up. However, there is no obvious evidence of other processes such as the 3{alpha}-process and subsequent hot bottom burning in our program stars. Such variation of the carbon and nitrogen abundances is not well understood by the present evolutionary models of low-mass and intermediate-mass stars.
