M. Lundkvist
A5028610409- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Space Exploration and Technology
- Astronomical and nuclear sciences
- Geophysics and Gravity Measurements
- History and Developments in Astronomy
- Scientific Research and Discoveries
- Adaptive optics and wavefront sensing
- Optical Polarization and Ellipsometry
- Nuclear physics research studies
- Fractal and DNA sequence analysis
- Solar and Space Plasma Dynamics
- Galaxies: Formation, Evolution, Phenomena
- Particle Accelerators and Free-Electron Lasers
- Calibration and Measurement Techniques
- Planetary Science and Exploration
- Pulsars and Gravitational Waves Research
- Advanced Statistical Methods and Models
- Geomagnetism and Paleomagnetism Studies
- Astrophysical Phenomena and Observations
Aarhus University
2015-2024
Heidelberg University
2016-2020
The University of Sydney
2014
We report on the masses, sizes, and orbits of planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits 7 revealed by precise Doppler measurements host Based an analysis brightness measurements, along with high-resolution imaging spectroscopy, (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all transiting (41 have FPP under 1%), constrain their sizes masses. Most smaller than three...
Various theoretical models treating the effect of stellar irradiation on planetary envelopes predict presence a radius valley: i.e. bimodal distribution planet radii, with super-Earths and sub-Neptune planets separated by valley at around $\approx 2~R_\oplus$. Such was observed recently, owing to an improvement in precision stellar, therefore radii. Here we investigate presence, location shape such using small sample highly accurate parameters determined from asteroseismology, which includes...
In the Solar system planets' compositions vary with orbital distance, rocky planets in close orbits and lower-density gas giants wider orbits. The detection of close-in giant around other stars was first clue that this pattern is not universal, can change substantially after their formation. Here we report another violation orbit-composition pattern: two orbiting same star distances differing by only 10%, densities a factor 8. One planet likely `super-Earth', whereas more akin to Neptune....
We present a study of 33 Kepler planet-candidate host stars for which asteroseismic observations have sufficiently high signal-to-noise ratio to allow extraction individual pulsation frequencies. implement new Bayesian scheme that is flexible in its input process oscillation frequencies, combinations them, and average parameters, derive robust fundamental properties these targets. Applying this grids evolutionary models yields stellar with median statistical uncertainties 1.2 per cent...
We have used asteroseismology to determine fundamental properties for 66 Kepler planet-candidate host stars, with typical uncertainties of 3% and 7% in radius mass, respectively. The results include new asteroseismic solutions four stars confirmed planets (Kepler-4, Kepler-14, Kepler-23 Kepler-25) increase the total number 77. A comparison stellar catalog by Batalha et al. shows that radii subgiants giants obtained from spectroscopic follow-up are systematically too low up a factor 1.5,...
Misaligned Planets Stars with multiple coplanar planets have not been seen to show misalignments between the equatorial plane of star and orbital planets—a diagnostic dynamical history planetary systems. Huber et al. (p. 331 ) analyzed Kepler 56 system, which contains a giant-sized an intermediate-sized planet. The orbits that are close coplanar, but misaligned stellar equator. A third companion in wide orbit, could be another or planet, explain configuration.
A search of the time-series photometry from NASA's Kepler spacecraft reveals a transiting planet candidate orbiting 11th magnitude G5 dwarf KIC 10593626 with period 290 days. The characteristics host star are well constrained by high-resolution spectroscopy combined an asteroseismic analysis photometry, leading to estimated mass and radius 0.970 ± 0.060 M☉ 0.979 0.020 R☉. depth 492 10 ppm for three observed transits yields 2.38 0.13 Re planet. system passes battery tests false positives,...
Abstract Simulations predict that hot super-Earth sized exoplanets can have their envelopes stripped by photoevaporation, which would present itself as a lack of these exoplanets. However, this absence in the exoplanet population has escaped firm detection. Here we demonstrate, using asteroseismology on sample and candidates observed during Kepler mission that, while there is an abundance with low incident fluxes, none are found high fluxes. We do not find any radii between 2.2 3.8 Earth...
The chemical composition of stars hosting small exoplanets (with radii less than four Earth radii) appears to be more diverse that gas-giant hosts, which tend metal-rich. This implies small, including Earth-size, planets may have readily formed at earlier epochs in the Universe's history when metals were scarce. We report Kepler spacecraft observations Kepler-444, a metal-poor Sun-like star from old population Galactic thick disk and host compact system five transiting with sizes between...
Results on the obliquity of exoplanet host stars—the angle between stellar spin axis and planetary orbital axis—provide important diagnostic information for theories describing formation. Here we present first application asteroseismology to problem determination in systems with transiting planets Sun-like stars. We consider two observed by NASA Kepler mission which have multiple small (super-Earth sized) planets: previously reported Kepler-50 a new system, Kepler-65, whose validate this...
Kepler has revolutionized our understanding of both exoplanets and their host stars. Asteroseismology is a valuable tool in the characterization stars an excellent observing facility to perform asteroseismology. Here we select sample 35 solar-type which transiting (or planet candidates) with detected solar-like oscillations. Using available short cadence data up Quarter 16 create power spectra optimized for asteroseismology We identify modes oscillation estimate mode frequencies by ‘peak...
NASA's Kepler Mission has revealed two transiting planets orbiting Kepler-68. Follow-up Doppler measurements have established the mass of innermost planet and a third jovian-mass beyond planets. Kepler-68b, in 5.4 day orbit 8.3 +/- 2.3 Earth, radius 2.31 0.07 Earth radii, density 3.32 0.92 (cgs), giving Kepler-68b intermediate between that ice giants Earth. Kepler-68c is Earth-sized with 0.953 transits on 9.6 orbit; validation posed unique challenges. Kepler-68d an orbital period 580 15 days...
We present new ground-based, multi-colour, broad-band photometric measurements of the physical parameters, transmission and emission spectra transiting extrasolar planet WASP-19b. The are based on observations eight transits four occultations through a Gunn i filter using 1.54-m Danish Telescope, 14 an Rc at Perth Exoplanet Survey Telescope (PEST) observatory one transit observed simultaneously optical (Sloan g′, r′, i′, z′) three near-infrared (J, H, K) filters, Gamma Ray Burst Optical...
The angle $\psi$ between a planet's orbital axis and the spin of its parent star is an important diagnostic planet formation, migration, tidal evolution. We seek empirical constraints on by measuring stellar inclination $i_{\rm s}$ via asteroseismology for ensemble 25 solar-type hosts observed with NASA's Kepler satellite. Our results are consistent alignment at 2-$\sigma$ level all stars in sample, meaning that system surrounding red-giant Kepler-56 remains as only unambiguous misaligned...
We present the discovery of TOI-197.01, first transiting planet identified by Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology host star is possible. TOI-197 (HIP116158) a bright (V=8.2 mag), spectroscopically classified subgiant oscillates with an average frequency about 430 muHz and displays clear signature mixed modes. The oscillation amplitude confirms that redder TESS bandpass compared to Kepler has small effect on oscillations, supporting expected yield thousands...
The measurement of obliquities in star-planet systems is great importance for the understanding planet system formation and evolution. bright well studied HAT-P-7 intriguing as several Rossiter-McLaughlin (RM) measurements found a large projected obliquity this system, but it was so far not possible to determine if orbit polar and/or retrograde. goal study measure stellar inclination hereby full 3D instead only 2D projection measured by RM effect. In addition we provide an updated set...
We present time-series photometric observations of thirteen transits in the planetary systems WASP-24, WASP-25 and WASP-26. All three have orbital obliquity measurements, WASP-24 WASP-26 been observed with Spitzer, was previously comparatively neglected. Our light curves were obtained using telescope-defocussing method scatters 0.5 to 1.2 mmag relative their best-fitting geometric models. used these data measure physical properties ephemerides high precision, finding that our improved...
Aims: We present 11 high-precision photometric transit observations of the transiting super-Earth planet GJ1214b. Combining these data with from other authors, we investigate ephemeris for possible signs timing variations (TTVs) using a Bayesian approach. Methods: The were obtained telescope-defocusing techniques, and achieve high precision random errors in photometry as low 1mmag per point. To possibility TTVs light curve, calculate overall probability TTV signal methods. Results: are used...
We report the discovery of Kepler-432b, a giant planet ($M_b = 5.41^{+0.32}_{-0.18} M_{\rm Jup}, R_b 1.145^{+0.036}_{-0.039} R_{\rm Jup}$) transiting an evolved star $(M_\star 1.32^{+0.10}_{-0.07} M_\odot, R_\star 4.06^{+0.12}_{-0.08} R_\odot)$ with orbital period $P_b 52.501129^{+0.000067}_{-0.000053}$ days. Radial velocities (RVs) reveal that Kepler-432b orbits its parent eccentricity $e 0.5134^{+0.0098}_{-0.0089}$, which we also measure independently asterodensity profiling (AP;...
We present photometric observations of four transits in the WASP-17 planetary system, obtained using telescope defocusing techniques and with scatters reaching 0.5 mmag per point. Our revised orbital period is 4.0 ± 0.6 s longer than previous measurements, a difference 6.6σ, does not support published detections eccentricity this system. model light curves jktebop code calculate physical properties system by recourse to five sets theoretical stellar predictions. The resulting radius, Rb =...
We report the first asteroseismic results obtained with Hertzsprung SONG Telescope from an extensive high-precision radial-velocity observing campaign of subgiant muHerculis. The data set was collected during 215 nights in 2014 and 2015. detected a total 49 oscillation modes l values 0 to 3, including some = 1 mixed modes. Based on rotational splitting observed modes, we determine period 52 days stellar inclination angle 63 degrees. parameters through modeling frequencies agree very well...
We determine the orbital eccentricities of individual small Kepler planets, through a combination asteroseismology and transit light-curve analysis. are able to constrain 51 systems with single transiting planet, which supplement our previous measurements 66 planets in multi-planet systems. Through Bayesian hierarchical analysis, we find evidence that only one detected planet have different eccentricity distribution than multiple planets. The single-transiting is well described by positive...
We present an analysis of the first 20-second cadence light curves obtained by TESS space telescope during its extended mission. find a precision improvement data compared to 2-minute for bright stars when binned same (~10-25% better T<~8 mag, reaching equal at T~13 mag), consistent with pre-flight expectations based on differences in cosmic ray mitigation algorithms. two results enabled this improvement. First, we use detect oscillations three solar analogs (gamma Pav, zeta Tuc and pi Men)...