- 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.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/PASP/106/452
- Title:
- Cool Dwarfs - Temperatures
- Short Name:
- J/PASP/106/452
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The file contains values of Cousins R-I and theta [= 5040/T(eff)] for 417 F-K stars which are on or near the main sequence.
- ID:
- ivo://CDS.VizieR/J/A+A/506/303
- Title:
- CoRoT-7 radial velocities
- Short Name:
- J/A+A/506/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on an intensive observational campaign carried out with HARPS at the 3.6m telescope at La Silla on the star CoRoT-7. Additional simultaneous photometric measurements carried out with the Euler Swiss telescope have demonstrated that the observed radial velocity variations are dominated by rotational modulation from cool spots on the stellar surface. Several approaches were used to extract the radial velocity signal of the planet(s) from the stellar activity signal.
- ID:
- ivo://CDS.VizieR/J/MNRAS/487/3162
- Title:
- Debris disc stars metallicity & Li properties
- Short Name:
- J/MNRAS/487/3162
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dwarf stars with debris discs and planets appear to be excellent laboratories to study the core accretion theory of planets formation. These systems are however, insufficiently studied. In this paper we present the main metallicity and lithium abundance properties of these stars together with stars with only debris discs and stars with only planets. Stars without detected planets nor discs are also considered. The analysed sample is formed by main-sequence FGK field single stars. Apart from the basic stellar parameters, we include the use of dusty discs masses. The main results show for the first time that the dust mass of debris disc stars with planets correlate with metallicity. We confirm that these disc dust masses are related to their central stellar masses. Separately, the masses of stars and those of planets also correlate with metallicity. We conclude that two conditions are necessary to form giant planets: to have a sufficient metallicity and also a sufficient protoplanetary mass of gas and dust. The debris discs masses of stars without giant planets do not correlate with metallicity, because they do not fulfil these two conditions. Concerning lithium, by adopting a stellar model for lithium depletion based on a strong interaction between the star and a protoplanetary disc, we found that in agreement with the model predictions, observations indicate that the main lithium depletion occurs during this initial protoplanetary evolution stage. We show that the ultimately lithium depletion is independent of the presence or absence of planets and appears to be only age dependent.
- ID:
- ivo://CDS.VizieR/J/ApJ/636/1098
- Title:
- Debris disks around solar-type stars
- Short Name:
- J/ApJ/636/1098
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have searched for infrared excesses around a well-defined sample of 69 FGK main-sequence field stars. These stars were selected without regard to their age, metallicity, or any previous detection of IR excess; they have a median age of 4Gyr.
- ID:
- ivo://CDS.VizieR/J/ApJ/688/597
- Title:
- Debris disks in NGC 2232
- Short Name:
- J/ApJ/688/597
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe Spitzer IRAC and MIPS observations of the nearby 25Myr old open cluster NGC 2232. Combining these data with ROSAT All-Sky Survey observations, proper motions, and optical photometry/spectroscopy, we construct a list of highly probable cluster members. We identify one A-type star, HD 45435, that has definite excess emission at 4.5-24um indicative of debris from terrestrial planet formation. We also identify 2-4 late-type stars with possible 8um excesses and 8 early-type stars with definite 24um excesses. Constraints on the dust luminosity and temperature suggest that the detected excesses are produced by debris disks. From our sample of B and A stars, stellar rotation appears to be correlated with 24um excess, a result that would be expected if massive primordial disks evolve into massive debris disks. To explore the evolution of the frequency and magnitude of debris around A-type stars, we combine our results with data for other young clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/441/653
- Title:
- 32 DENIS nearby red dwarfs
- Short Name:
- J/A+A/441/653
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectra of 36 nearby star candidates and 3 red giant candidates, identified in the DENIS database. 32 of the dwarf candidates are nearby red dwarfs, with spectral types from M5.5 to M8.5. Out of 11 targets with low proper motion (mu<0.1arcsec/yr) but a Reduced Proper Motion above an inclusive threshold, 9 are red dwarfs. The 4 contaminants are all reddened F-K main sequence stars, and could have been eliminated by checking for small well-known high latitude molecular clouds. These stars might be of interest as probes of interstellar absorption. For the red dwarfs we derive spectral types and spectroscopic distances, using a new calibration of the PC3 spectral index to absolute magnitudes in the I, J, H and K photometric bands. We confirm 2 new members of the 12 pc volume (2 new M8.5), and one M7.5 NLTT object closer than 10pc; and show that one quarter of the stars with photometric distances under 30pc have too small a proper motion for inclusion in the NLTT catalog.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/1507
- Title:
- Detached M dwarf eclipsing binaries in WTS
- Short Name:
- J/MNRAS/426/1507
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 16 detached M dwarf eclipsing binaries (MEBs) with J<16mag and provide a detailed characterization of three of them, using high-precision infrared light curves from the WFCAM Transit Survey (WTS). Such systems provide the most accurate and model-independent method for measuring the fundamental parameters of these poorly understood yet numerous stars, which currently lack sufficient observations to precisely calibrate stellar evolution models.
- ID:
- ivo://CDS.VizieR/J/A+A/433/185
- Title:
- Detailed abundance analysis of 102 F and G dwarfs
- Short Name:
- J/A+A/433/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a detailed elemental abundance analysis of 102 F and G dwarf stars we present abundance trends in the Galactic thin and thick disks for 14 elements (O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, Y, Ba, and Eu). Stellar parameters and elemental abundances (except for Y, Ba and Eu) for 66 of the 102 stars were presented in our previous studies (Bensby et al. 2003, <J/A+A/410/527>, 2004, <J/A+A/415/155>). The 36 stars that are new in this study extend and confirm our previous results and allow us to draw further conclusions regarding abundance trends. The s-process elements Y and Ba, and the r-element Eu have also been considered here for the whole sample for the first time. To make it easier to gather the elemental abundances for all 102 stars we have included the abundance data from Bensby et al. (2003, Cat. <J/A+A/410/527>) and from Bensby et al. (2004, Cat. <J/A+A/415/155>) in table9.dat
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/2263
- Title:
- Differential photometry of the EB* HATS551-027
- Short Name:
- J/MNRAS/451/2263
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery and characterization of a new M-dwarf binary, with component masses and radii of M_1_=0.244_-0.003_^+0.003^M_{sun}_, R_1_=0.261_-0.009_^+0.006^R_{sun}_, M_2_=0.179_-0.001_^+0.002^M_{sun}_, R_2_=0.218_-0.011_^+0.007^R_{sun}_, and orbital period of ~4.1 d. The M-dwarf binary HATS551-027 (LP 837-20) was identified as an eclipsing binary by the HATSouth survey, and characterized by a series of high-precision photometric observations of the eclipse events, and spectroscopic determinations of the atmospheric parameters and radial velocity orbits. HATS551-027 is one of few systems with both stellar components lying in the fully convective regime of very low mass stars, and can serve as a test for stellar interior models. The radius of HATS551-027A is consistent with models to 1{sigma}, whilst HATS551-027B is inflated by 9 percent at 2{sigma} significance. We measure the effective temperatures for the two stellar components to be T_eff,1_=3190+/-100K and T_eff,2_=2990+/-110K; both are slightly cooler than theoretical models predict, but consistent with other M-dwarfs of similar masses that have previously been studied. We also measure significant H{alpha} emission from both components of the binary system, and discuss this in the context of the correlation between stellar activity and the discrepancies between the observed and model temperatures.
