- ID:
- ivo://CDS.VizieR/J/A+A/601/A67
- Title:
- Kepler solar-type stars modeling
- Short Name:
- J/A+A/601/A67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler space telescope yielded unprecedented data for the study of solar-like oscillations in other stars. The large samples of multi-year observations posed an enormous data analysis challenge that has only recently been surmounted. Asteroseismic modeling has become more sophisticated over time, with better methods gradually developing alongside the extended observations and improved data analysis techniques. We apply the latest version of the Asteroseismic Modeling Portal (AMP) to the full-length Kepler data sets for 57 stars, comprising planetary hosts, binaries, solar-analogs, active stars, and for validation purposes, the Sun. From an analysis of the derived stellar properties for the full sample, we identify a variation of the mixing-length parameter with atmospheric properties. We also derive a linear relation between the stellar age and a characteristic frequency separation ratio. In addition, we find that the empirical correction for surface effects suggested by Kjeldsen and coworkers is adequate for solar-type stars that are not much hotter (Teff<~6200K) or significantly more evolved (logg>~4.2, <{Delta}{nu}> >~80uHz80) than the Sun. Precise parallaxes from the Gaia mission and future observations from TESS and PLATO promise to improve the reliability of stellar properties derived from asteroseismology.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/429/1466
- Title:
- Kepler stars in the NGC 6866 field
- Short Name:
- J/MNRAS/429/1466
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of stars in the field of the open cluster NGC 6866 (age 650Myr) using data from the Kepler Input Catalogue (KIC) and time series photometry from the Kepler data base. We identify 31 {delta} Scuti and 8 {gamma} Doradus pulsating variables as well as 23 red giants with solar-like oscillations. There are 4 eclipsing binaries and 106 stars showing rotational modulation indicative of starspots. We attempted to identify cluster members using their proper motions but found very poor discrimination between members and non-members. The KIC shows a concentration of stars with distance modulus V_0_-M_V_=10.47+/-0.02. We used assumed radial modes in 9 {delta} Sct stars to determine their asteroseismic luminosities and found that the distance modulus falls within three narrow ranges depending on the assignment of overtone number. One of these ranges coincides with the KIC distance modulus. The rotation periods of main-sequence stars are correlated with colour, so that a period-age-mass relation can be derived from open clusters and applied to stars of unknown ages. Surprisingly, we find that the correlation applies not only to cool stars, but extends to A-type stars in the cluster. Finally, we present measurements of solar-like oscillations in red giants, a few of which might be cluster members.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/91
- Title:
- Kepler stars with infrared excess
- Short Name:
- J/MNRAS/426/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a search for infrared excess emission from dusty circumstellar material around 180000 stars observed by the Kepler and Wide-field Infrared Survey Explorer missions. This study is motivated by (i) the potential to find bright warm discs around planet host stars, (ii) a need to characterize the distribution of rare warm discs and (iii) the possible identification of candidates for discovering transiting dust concentrations. We find about 8000 stars that have excess emission, mostly at 12um.
- ID:
- ivo://CDS.VizieR/J/MNRAS/472/1618
- Title:
- Kepler study of starspot lifetimes
- Short Name:
- J/MNRAS/472/1618
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Wide-field high-precision photometric surveys such as Kepler have produced reams of data suitable for investigating stellar magnetic activity of cooler stars. Starspot activity produces quasi-sinusoidal light curves whose phase and amplitude vary as active regions grow and decay over time. Here we investigate, first, whether there is a correlation between the size of starspots - assumed to be related to the amplitude of the sinusoid - and their decay time-scale and, secondly, whether any such correlation depends on the stellar effective temperature. To determine this, we computed the auto-correlation functions of the light curves of samples of stars from Kepler and fitted them with apodised periodic functions. The light-curve amplitudes, representing spot size, were measured from the root-mean-squared scatter of the normalized light curves. We used a Monte Carlo Markov Chain to measure the periods and decay time-scales of the light curves. The results show a correlation between the decay time of starspots and their inferred size. The decay time also depends strongly on the temperature of the star. Cooler stars have spots that last much longer, in particular for stars with longer rotational periods. This is consistent with current theories of diffusive mechanisms causing starspot decay. We also find that the Sun is not unusually quiet for its spectral type - stars with solar-type rotation periods and temperatures tend to have (comparatively) smaller starspots than stars with mid-G or later spectral types.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/2342
- Title:
- 4 Kepler systems transit timing observations
- Short Name:
- J/MNRAS/421/2342
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a method to confirm the planetary nature of objects in systems with multiple transiting exoplanet candidates. This method involves a Fourier-domain analysis of the deviations in the transit times from a constant period that result from dynamical interactions within the system. The combination of observed anticorrelations in the transit times and mass constraints from dynamical stability allow us to claim the discovery of four planetary systems, Kepler-25, Kepler-26, Kepler-27 and Kepler-28, containing eight planets and one additional planet candidate.
7556. Kepler Target Search
- ID:
- ivo://archive.stsci.edu/kepler_fov
- Title:
- Kepler Target Search
- Short Name:
- KIC_CT
- Date:
- 12 Feb 2020 19:50:32
- Publisher:
- Space Telescope Science Institute Archive
- Description:
- The Kepler Target Search interface provides access to a 12.5 million row table created by MAST by joining entries from the Kepler Input catalog (KIC) with the Kepler Characteristics table (CT) and merging these with "associated" entries from the United Kingdom Infrared Telescope (IRT) project, the USNOb catalog, GALEX, the Kepler Isaac Newton Telescope Survey (KIS), and the Everett KPNO (UBV) survey. The search interface allows users to find targets within the Kepler field of view (FOV) and allows searches on magnitudes, colors, and other parameters for both KIC and associated non-KIC targets. This is the recommended interface for potential guest observers to locate possible targets for observation. GO proposers however should check on the target's position by either (or both) looking to one of our posted FFI images and seeing if it is on a chip, and (2) confirming this with the GO office.
- ID:
- ivo://CDS.VizieR/J/AJ/152/105
- Title:
- Kepler-80 transit timing observations
- Short Name:
- J/AJ/152/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kepler has discovered hundreds of systems with multiple transiting exoplanets which hold tremendous potential both individually and collectively for understanding the formation and evolution of planetary systems. Many of these systems consist of multiple small planets with periods less than ~50 days known as Systems with Tightly spaced Inner Planets, or STIPs. One especially intriguing STIP, Kepler-80 (KOI-500), contains five transiting planets: f, d, e, b, and c with periods of 1.0, 3.1, 4.6, 7.1, and 9.5 days, respectively. We provide measurements of transit times and a transit timing variation (TTV) dynamical analysis. We find that TTVs cannot reliably detect eccentricities for this system, though mass estimates are not affected. Restricting the eccentricity to a reasonable range, we infer masses for the outer four planets (d, e, b, and c) to be 6.75_-0.51_^+0.69^, 4.13_-0.95_^+0.81^, 6.93_-0.70_^+1.05^, and 6.74_-0.86_^+1.23^ Earth masses, respectively. The similar masses but different radii are consistent with terrestrial compositions for d and e and ~2% H/He envelopes for b and c. We confirm that the outer four planets are in a rare dynamical configuration with four interconnected three-body resonances that are librating with few degree amplitudes. We present a formation model that can reproduce the observed configuration by starting with a multi-resonant chain and introducing dissipation. Overall, the information-rich Kepler-80 planets provide an important perspective into exoplanetary systems.
- ID:
- ivo://CDS.VizieR/J/ApJS/208/16
- Title:
- Kepler transit timing observations. VIII.
- Short Name:
- J/ApJS/208/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following the works of Ford et al. (2011, Cat. J/ApJS/197/2; 2012ApJ...756..185F) and Steffen et al. (2012ApJ...756..186S) we derived the transit timing of 1960 Kepler objects of interest (KOIs) using the pre-search data conditioning light curves of the first twelve quarters of the Kepler data. For 721 KOIs with large enough signal-to-noise ratios, we obtained also the duration and depth of each transit. The results are presented as a catalog for the community to use. We derived a few statistics of our results that could be used to indicate significant variations. Including systems found by previous works, we have found 130 KOIs that showed highly significant times of transit variations (TTVs) and 13 that had short-period TTV modulations with small amplitudes. We consider two effects that could cause apparent periodic TTV -- the finite sampling of the observations and the interference with the stellar activity, stellar spots in particular. We briefly discuss some statistical aspects of our detected TTVs. We show that the TTV period is correlated with the orbital period of the planet and with the TTV amplitude.
7559. Kepler triples
- ID:
- ivo://CDS.VizieR/J/MNRAS/455/4136
- Title:
- Kepler triples
- Short Name:
- J/MNRAS/455/4136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We produce and analyse eclipse time variation (ETV) curves for some 2600 Kepler binaries. We find good to excellent evidence for a third body in 222 systems via either the light-travel-time (LTTE) or dynamical effect delays. Approximately half of these systems have been discussed in previous work, while the rest are newly reported here. Via detailed analysis of the ETV curves using high-level analytic approximations, we are able to extract system masses and information about the three-dimensional characteristics of the triple for 62 systems which exhibit both LTTE and dynamical delays; for the remaining 160 systems, we give improved LTTE solutions. New techniques of pre-processing the flux time series are applied to eliminate false positive triples and to enhance the ETV curves. The set of triples with outer orbital periods shorter than ~2000d is now sufficiently numerous for meaningful statistical analysis. We find that (i) there is a peak near i_m_=~40{deg} in the distribution of the triple versus inner binary mutual inclination angles that provides strong confirmation of the operation of Kozai-Lidov cycles with tidal friction; (ii) the median eccentricity of the third-body orbits is e_2_=0.35; (iii) there is a deficit of triple systems with binary periods <~1d and outer periods between ~50 and 200d which might help guide the refinement of theories of the formation and evolution of close binaries; and (iv) the substantial fraction of Kepler binaries which have third-body companions is consistent with a very large fraction of all binaries being part of triples.
- ID:
- ivo://CDS.VizieR/J/ApJ/900/L44
- Title:
- Kepler TTVs for 6 exomoon candidates
- Short Name:
- J/ApJ/900/L44
- Date:
- 15 Feb 2022 13:03:49
- Publisher:
- CDS
- Description:
- It has been recently claimed that KOIs-268.01, 303.01, 1888.01, 1925.01, 2728.01, and 3320.01 are exomoon candidates, based on an analysis of their transit timing. Here, we perform an independent investigation, which is framed in terms of three questions: (1) Are there significant transit timing variations (TTVs)? (2) Is there a significant periodic TTV? (3) Is there evidence for a nonzero moon mass? We applied rigorous statistical methods to these questions alongside a reanalysis of the Kepler photometry and find that none of the Kepler objects of interest (KOIs) satisfy our three tests. Specifically, KOIs-268.01 and 3220.01 pass none of the tests and KOIs-303.01, 1888.01, and 1925.01 pass a single test each. Only KOI-2728.01 satisfies two, but fails the cross-validation test for predictions. Further, detailed photodynamical modeling reveals that KOI-2728.01 favors a negative-radius moon (as does KOI-268.01). We also note that we find a significant photoeccentric effect for KOI-1925.01 indicating an eccentric orbit of at least e>(0.62+/-0.06). For comparison, we applied the same tests to Kepler-1625b, which reveals that (1) and (3) are passed, but (2) cannot be checked with the cross- validation method used here, due to the limited number of available epochs. In conclusion, we find no compelling evidence for exomoons among the six KOIs. Despite this, we were able to derive exomoon mass upper limits versus semimajor axis, with KOI-3220.01 leading to particularly impressive constraints of MS/MP<0.4% [2{sigma}] at a similar semimajor to that of the Earth-Moon.