- ID:
- ivo://CDS.VizieR/J/ApJS/199/30
- Title:
- Effective temperature scale for KIC stars
- Short Name:
- J/ApJS/199/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of revised effective temperatures for stars observed in long-cadence mode in the Kepler Input Catalog (KIC). We use Sloan Digital Sky Survey (SDSS) griz filters tied to the fundamental temperature scale. Polynomials for griz color-temperature relations are presented, along with correction terms for surface gravity effects, metallicity, and statistical corrections for binary companions or blending. We compare our temperature scale to the published infrared flux method (IRFM) scale for V_T_JKs in both open clusters and the Kepler fields. We find good agreement overall, with some deviations between (J-Ks)-based temperatures from the IRFM and both SDSS filter and other diagnostic IRFM color-temperature relationships above 6000K. For field dwarfs, we find a mean shift toward hotter temperatures relative to the KIC, of order 215K, in the regime where the IRFM scale is well defined (4000K to 6500K). This change is of comparable magnitude in both color systems and in spectroscopy for stars with T_eff_ below 6000K. Systematic differences between temperature estimators appear for hotter stars, and we define corrections to put the SDSS temperatures on the IRFM scale for them. When the theoretical dependence on gravity is accounted for, we find a similar temperature scale offset between the fundamental and KIC scales for giants. We demonstrate that statistical corrections to color-based temperatures from binaries are significant. Typical errors, mostly from uncertainties in extinction, are of order 100K.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/367/1329
- Title:
- Elemental abundances for 176 stars
- Short Name:
- J/MNRAS/367/1329
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed an abundance analysis for F- and G- dwarfs of the Galactic thick-disc component. A sample of 176 nearby (d<=150pc) thick-disc candidate stars was chosen from the Hipparcos catalogue and subjected to a high-resolution spectroscopic analysis. Using accurate radial velocities combined with the Hipparcos astrometry, kinematics (U, V and W) and Galactic orbital parameters were computed. We estimate the probability for a star to belong to the thin disc, the thick disc or the halo. With a probability P>=70 per cent taken as certain membership, we assigned 95 stars to the thick disc, 13 to the thin disc, and 20 to the halo. The remaining 48 stars in the sample cannot be assigned with reasonable certainty to one of the three components. Abundances of C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Ba, Ce, Nd and Eu have been obtained.
- ID:
- ivo://CDS.VizieR/J/MNRAS/364/272
- Title:
- Elemental abundances in Blanco 1
- Short Name:
- J/MNRAS/364/272
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectroscopy is used to determine the detailed chemical abundances of a group of eight F- and G-type stars in the young open cluster Blanco 1. An average [Fe/H] of +0.04+/-0.02 (internal error)+/-0.04 (external error) is found, considerably lower than a previous spectroscopic estimate for this cluster. The difference is due mainly to our adoption of significantly cooler temperatures that are consistent with both photometric and spectroscopic constraints. Blanco 1 exhibits subsolar [Ni/Fe](0.18+/-0.01+/-0.01), [Si/Fe](0.09+/-0.02+/-0.03), [Mg/Fe](0.14+/-0.02+/-0.03) and [Ca/Fe](0.09+/-0.03+/-0.03); ratios that are not observed among nearby field stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/563
- Title:
- Elemental abundances in Hyades supercluster
- Short Name:
- J/MNRAS/415/563
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The existence of a kinematically defined moving group of stars centred at U=-40, V=-17km/s, referred to as the Hyades supercluster, has been suggested to be the debris of an originally large star-forming event, with its core being the present-day Hyades open cluster. Using high-resolution UV-Visual Echelle Spectrograph (UVES) spectra, we present the elemental abundances for a range of alpha, Fe-peak and neutron-capture elements for 26 proposed supercluster stars. Our results show that the sample stars display a heterogeneous abundance distribution, with a clump around [Fe/H]=+0.15. We also calculate stellar radial velocities and U, V, W space velocities. Enforcing strict chemical and kinematical membership criteria, we find that four supercluster stars share the Hyades open cluster abundances and kinematics, while many of the remaining stars fit the disc field kinematics and abundance range. We discuss our findings in the context of the Hyades supercluster being a dispersed star-forming remnant, a stellar stream of purely dynamical origin or a result of several processes.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1111
- Title:
- Elemental abundances of field red giants
- Short Name:
- J/AJ/130/1111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We summarize a selection process to identify red giants in the direction of the southern warp of the Galactic disk, employing VI_C_ photometry and multi-object spectroscopy.
- ID:
- ivo://CDS.VizieR/J/AJ/155/68
- Title:
- Elemental abundances of KOIs in APOGEE. I.
- Short Name:
- J/AJ/155/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has observed ~600 transiting exoplanets and exoplanet candidates from Kepler (Kepler Objects of Interest, KOIs), most with >=18 epochs. The combined multi-epoch spectra are of high signal-to-noise ratio (typically >=100) and yield precise stellar parameters and chemical abundances. We first confirm the ability of the APOGEE abundance pipeline, ASPCAP, to derive reliable [Fe/H] and effective temperatures for FGK dwarf stars - the primary Kepler host stellar type - by comparing the ASPCAP-derived stellar parameters with those from independent high-resolution spectroscopic characterizations for 221 dwarf stars in the literature. With a sample of 282 close-in (P<100 days) KOIs observed in the APOGEE KOI goal program, we find a correlation between orbital period and host star [Fe/H] characterized by a critical period, P_crit_=8.3_-4.1_^+0.1^ days, below which small exoplanets orbit statistically more metal-enriched host stars. This effect may trace a metallicity dependence of the protoplanetary disk inner radius at the time of planet formation or may be a result of rocky planet ingestion driven by inward planetary migration. We also consider that this may trace a metallicity dependence of the dust sublimation radius, but we find no statistically significant correlation with host T_eff_ and orbital period to support such a claim.
- ID:
- ivo://CDS.VizieR/J/AJ/159/46
- Title:
- Elemental abundances of 416 stars in 5 dSphs of M31
- Short Name:
- J/AJ/159/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep spectroscopy from Keck/DEIMOS (DEep Imaging Multi-Object Spectrograph) of Andromeda I, III, V, VII, and X, all of which are dwarf spheroidal satellites (dSphs) of M31. The sample includes 256 spectroscopic members across all five dSphs. We confirm previous measurements of the velocity dispersions and dynamical masses, and we provide upper limits on bulk rotation. Our measurements confirm that M31 satellites obey the same relation between stellar mass and stellar metallicity as Milky Way (MW) satellites and other dwarf galaxies in the Local Group. The metallicity distributions show trends with stellar mass that are similar to those of MW satellites, including evidence in massive satellites for external influence, like pre-enrichment or gas accretion. We present the first measurements of individual element ratios, like [Si/Fe], in the M31 system, as well as measurements of the average [{alpha}/Fe] ratio. The trends of [{alpha}/Fe] with [Fe/H] also follow the same galaxy mass-dependent patterns as MW satellites. Less massive galaxies have more steeply declining slopes of [{alpha}/Fe] that begin at lower [Fe/H]. Finally, we compare the chemical evolution of M31 satellites to M31's Giant Stellar Stream and smooth halo. The properties of the M31 system support the theoretical prediction that the inner halo is composed primarily of massive galaxies that were accreted early. As a result, the inner halo exhibits higher [Fe/H] and [{alpha}/Fe] than surviving satellite galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/884
- Title:
- EMBLA survey. Galactic bulge metal-poor stars
- Short Name:
- J/MNRAS/460/884
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cosmological models predict the oldest stars in the Galaxy should be found closest to the centre of the potential well, in the bulge. The Extremely Metal-poor BuLge stars with AAOmega survey (EMBLA) successfully searched for these old, metal-poor stars by making use of the distinctive SkyMapper photometric filters to discover candidate metal-poor stars in the bulge. Their metal-poor nature was then confirmed using the AAOmega spectrograph on the Anglo-Australian Telescope. Here we present an abundance analysis of 10 bulge stars with -2.8<[Fe/H]<-1.7 from MIKE/Magellan observations, in total determining the abundances of 22 elements. Combining these results with our previous high-resolution data taken as part of the Gaia-ESO Survey, we have started to put together a picture of the chemical and kinematic nature of the most metal-poor stars in the bulge. The currently available kinematic data are consistent with the stars belonging to the bulge, although more accurate measurements are needed to constrain the stars' orbits. The chemistry of these bulge stars deviates from that found in halo stars of the same metallicity. Two notable differences are the absence of carbon-enhanced metal-poor bulge stars, and the {alpha} element abundances exhibit a large intrinsic scatter and include stars which are underabundant in these typically enhanced elements.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/1043
- Title:
- Emission-line galaxies from SDSS DR7
- Short Name:
- J/MNRAS/421/1043
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 2865 emission-line galaxies with strong nebular HeII{lambda}4686 emissions in the Sloan Digital Sky Survey Data Release 7 and use this sample to investigate the origin of this line in star-forming galaxies. We show that star-forming galaxies and galaxies dominated by an active galactic nucleus form clearly separated branches in the HeII{lambda}4686/H{beta} versus [NII]{lambda}6584/H{alpha} diagnostic diagram and derive an empirical classification scheme which separates the two classes. We also present an analysis of the physical properties of 189 star-forming galaxies with strong HeII{lambda}4686 emissions. These star-forming galaxies provide constraints on the hard ionizing continuum of massive stars.
- ID:
- ivo://CDS.VizieR/J/AJ/143/145
- Title:
- Emission-line objects from ALFALFA H{alpha} survey
- Short Name:
- J/AJ/143/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- During a wide-field narrowband H{alpha} imaging survey, we noted the presence of numerous isolated emission-line point sources in the data. These objects could represent ultra-low-luminosity galaxies at low-redshift (detection via H{alpha}), isolated extragalactic HII regions associated with the galaxy targeted by the original observation, or background galaxies or QSOs where strong emission lines (most often [OIII]{lambda}5007) redshift into our narrowband filter. We have carried out a systematic search for these "H{alpha} dots" in over 200 15x15arcmin fields. To date we have cataloged 61 candidate emission-line sources in roughly 11.7deg^2^. The sample has a median R magnitude of 19.5, and detects objects as faint as R=22.6. Follow-up spectroscopy reveals that ~85% of the candidates are bona fide emission-line objects, with roughly 60% of the real sources being lower-redshift objects (detection via H{alpha}) and 40% being higher-redshift objects detected via [OIII] emission or some other emission line. Here we present the results of our initial survey and follow-up spectroscopy. We use our sample to study the properties (including star-formation rates and metal abundances) of low-luminosity star-forming galaxies in the nearby universe and of low-metallicity star-forming galaxies at z~0.33.
