- ID:
- ivo://CDS.VizieR/J/A+A/631/A34
- Title:
- KELT-9b radial velocity curve
- Short Name:
- J/A+A/631/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the framework of the GAPS project, we observed the planet-hosting star KELT-9 (A-type star, vsini~110km/s) with the HARPS-N spectrograph at the Telescopio Nazionale Galileo. In this work we analyse the spectra and the extracted radial velocities, to constrain the physical parameters of the system and to detect the planetary atmosphere of KELT-9b. We extracted from the high-resolution optical spectra the mean stellar line profiles with an analysis based on the Least Square Deconvolution technique. Then, we computed the stellar radial velocities with a method optimized for fast rotators, by fitting the mean stellar line profile with a purely rotational profile instead of using a Gaussian function. The new spectra and analysis led us to update the orbital and physical parameters of the system, improving in particular the value of the planetary mass to Mp=2.88+/-0.35M_Jup_. We discovered an anomalous in-transit radial velocity deviation from the theoretical Rossiter- McLaughlin effect solution, calculated from the projected spin-orbit angle {lambda}=-85.78+/-0.46 degrees measured with Doppler tomography. We prove that this deviation is caused by the planetary atmosphere of KELT-9b, thus we name this effect Atmospheric Rossiter-McLaughlin effect. By analysing the magnitude of the radial velocity anomaly, we obtained information on the extension of the planetary atmosphere as weighted by the model used to retrieve the stellar mean line profiles, which is up to 1.22+/-0.02Rp. The Atmospheric Rossiter-McLaughlin effect will be observable for other exo- planets whose atmosphere has non-negligible correlation with the stellar mask used to retrieve the radial velocities, in particular ultra-hot Jupiters with iron in their atmosphere. The duration and amplitude of the effect will depend not only on the extension of the atmosphere, but also on the in-transit planetary radial velocities and on the projected rotational velocity of the parent star.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/761/123
- Title:
- KELT-1 photometry and spectroscopy follow-up
- Short Name:
- J/ApJ/761/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of KELT-1b, the first transiting low-mass companion from the wide-field Kilodegree Extremely Little Telescope-North (KELT-North) transit survey. A joint analysis of the spectroscopic, radial velocity, and photometric data indicates that the V=10.7 primary is a mildly evolved mid-F star with T_eff_=6516+/-49K, logg=4.228^+0.014^_-0.021_, and [Fe/H]=0.052+/-0.079, with an inferred mass M_*_=1.335+/-0.063M_{sun}_ and radius R_*_=1.471^+0.045^_-0.035_R_{sun}_. The companion is a low-mass brown dwarf or a super-massive planet with mass M_P_=27.38+/-0.93M_Jup_ and radius R_P_=1.116^+0.038^_-0.029_R_Jup_. The companion is on a very short (~29 hr) period circular orbit, with an ephemeris T_c_ (BJD_TDB_)=2455909.29280+/-0.00023 and P=1.217501+/-0.000018 days. KELT-1b receives a large amount of stellar insolation, resulting in an estimated equilibrium temperature assuming zero albedo and perfect redistribution of T_eq_=2423^+34^_-27_K. Comparison with standard evolutionary models suggests that the radius of KELT-1b is likely to be significantly inflated. Adaptive optics imaging reveals a candidate stellar companion to KELT-1 with a separation of 588+/-1mas, which is consistent with an M dwarf if it is at the same distance as the primary. Rossiter-McLaughlin measurements during transit imply a projected spin-orbit alignment angle {lambda}=2+/-16deg, consistent with a zero obliquity for KELT-1. Finally, the vsinI_*_=56+/-2km/s of the primary is consistent at ~2{sigma} with tidal synchronization. Given the extreme parameters of the KELT-1 system, we expect it to provide an important testbed for theories of the emplacement and evolution of short-period companions, as well as theories of tidal dissipation and irradiated brown dwarf atmospheres.
- ID:
- ivo://CDS.VizieR/J/AJ/158/113
- Title:
- Kepler-13AB aperture photometry
- Short Name:
- J/AJ/158/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the high-resolution imaging instrument, 'Alopeke, at the Gemini-N telescope, we obtained simultaneous two-channel time-series observations of the binary exoplanet host star Kepler13-AB. Our optical observations were obtained during a transit event of the exoplanet Kepler-13b and light curves were produced using both speckle interferometric and aperture photometry techniques. Both techniques confirm that the transiting object orbits the star Kepler-13A while different transit depths are seen across the optical wavelength range, being ~2 times deeper in the blue. These measurements, as well as mass determinations in the literature, are consistent with Kepler-13b being a highly irradiated gas giant with a bloated atmosphere. Our observations highlight the ability of high-resolution speckle imaging to not only assess binarity in exoplanet host stars but robustly determine which of the stars the transiting object actually orbits.
- ID:
- ivo://CDS.VizieR/J/MNRAS/469/2907
- Title:
- Kepler-410Ab transit timing variations
- Short Name:
- J/MNRAS/469/2907
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For the determination of the individual times of transit we used short- cadence (sampled every 58.8 seconds) de-trended data (PDCSAP_FLUX) from quarters Q1 to Q17, provided by the NASA Exoplanet Archive. As a first step, we extracted parts of the LC around detected transits using the ephemeris given in Van Eylen et al. (2014ApJ...782...14V), where we took an interval 0.2 days around the computed transit time (the interval size is approximately double the transit duration). To remove additional residual trends caused by the stellar activity and instrumental long-term photometric variation, we fitted the out-of-transit part of LC by a second-order polynomial function. Then we subtracted 8% flux contamination from the wide companion Kepler-410B, according to calculations of Van Eylen et al. (2014ApJ...782...14V). All individual parts of the LC with transits were stacked together to obtain the template of the transit. The stacked LC was fitted by our software implementation of Mandel & Agol (2002ApJ...580L.117M) model, where we used theMarkov Chain Monte Carlo (MCMC) simulation method for the determination of transit parameters. This method takes into account individual errors of Kepler observations and gives a realistic and statistically significant estimate of parameter errors. As a starting point for the MCMC fitting, we used the physical parameters of the planet given in Van Eylen et al. (2014ApJ...782...14V). We have adopted a fixed value a=0.1226AU. We have used a quadratic model of limb darkening with starting values of coefficients from Sing (2010, Cat. J/A+A/510/A21). We ran the MCMC simulation with 10^6^ steps. We have repeated the MCMC simulation with the previous solution as the starting point on each of 70 individual transit intervals, and let only the time of transit to update. The new values were used to improve the linear ephemeris and to construct a new O-C diagram. The combined light curve stacked using a linear ephemeris is affected by relatively large amplitude of O-C time shifts. To correct this effect, we used iterative procedure that takes the best-fit O-C values into account. Afterwards, a new stacked light curve was constructed and a new MCMC transit solution was calculated, subsequently a new ephemeris and O-C values were determined. This process was repeated three times until a convergent solution was reached.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/2634
- Title:
- Kepler and K2 best candidates for planets
- Short Name:
- J/MNRAS/465/2634
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A crucial step in planet hunting surveys is to select the best candidates for follow-up observations, given limited telescope resources. This is often performed by human 'eyeballing', a time consuming and statistically awkward process. Here, we present a new, fast machine learning technique to separate true planet signals from astrophysical false positives. We use self-organizing maps (SOMs) to study the transit shapes of Kepler and K2 known and candidate planets. We find that SOMs are capable of distinguishing known planets from known false positives with a success rate of 87.0 per cent, using the transit shape alone. Furthermore, they do not require any candidate to be dispositioned prior to use, meaning that they can be used early in a mission's lifetime. A method for classifying candidates using a SOM is developed, and applied to previously unclassified members of the Kepler Objects of Interest (KOI) list as well as candidates from the K2 mission. The method is extremely fast, taking minutes to run the entire KOI list on a typical laptop. We make PYTHON code for performing classifications publicly available, using either new SOMs or those created in this work. The SOM technique represents a novel method for ranking planetary candidate lists, and can be used both alone or as part of a larger autovetting code.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A29
- Title:
- Kepler-278 and Kepler-391 spectra
- Short Name:
- J/A+A/634/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kepler-278 and Kepler-391 are two of the three evolved stars on the red giant branch (RGB) known to date, to host multiple short-period transiting planets. Moreover, these planets are among the smallest discovered around RGB stars. Here, we present a detailed stellar and planetary characterization of these remarkable systems. Methods. Based on high-quality spectra from Gemini-GRACES of Kepler-278 and Kepler-391, we obtained refined stellar parameters and precise chemical abundances of 25 elements. Nine of these elements and the carbon isotopic ratios, ^12^C/^13^C, were not previously measured. Also, combining our new stellar parameters with a photodynamical analysis of the Kepler light curves, we determined accurate planetary properties of both systems. Results. Our revised stellar parameters agree reasonably well with most of the previous results, although we find that Kepler-278 is ~15% less massive than previously reported. The abundances of C, N, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, and Ce, in both stars, are consistent with those of evolved nearby thin disk stars. Kepler-391 presents a relatively high abundance of lithium (A(Li)NLTE=1.29+/-0.09dex), which is likely a remnant from the main-sequence phase. The precise spectroscopic parameters of Kepler-278 and Kepler-391 along with their high 12 C/13 C ratios show that both stars are just starting their ascent on the RGB. The planets Kepler-278b, Kepler-278c, and Kepler-391c are warm sub-Neptunes, whilst Kepler-391b is a hot sub-Neptune that falls in the Hot Super-Earth desert and therefore it might be undergoing photo-evaporation of its outer envelope. The high-precision obtained in the transit times allowed us not only to confirm Kepler-278c's TTV signal but also to find evidence of a previously undetected TTV signal for the inner planet Kepler-278b. From the presence of gravitational interaction between these bodies we constrain, for the first time, the mass of Kepler-278b (Mp=56M_Earth_) and Kepler-278c (Mp=35M_Earth_). The mass limits, coupled with our precise determinations of the planetary radii, suggest that their bulk compositions are consistent with a significant amount of water content and the presence of H2 gaseous envelopes. Finally, our photodynamical analysis also shows that the orbits of both planets around Kepler-278 are highly eccentric (e~0.7) and, surprisingly, coplanar. Further observations (e.g., precise radial velocities) of this system are needed to confirm the eccentricity values presented here.
- ID:
- ivo://CDS.VizieR/J/MNRAS/412/1210
- Title:
- Kepler asteroseismic targets
- Short Name:
- J/MNRAS/412/1210
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar structure and evolution can be studied in great detail by asteroseismic methods, provided data of high precision are available. We determine the effective temperature (Teff), surface gravity (logg), metallicity, and the projected rotational velocity (vsini) of 44 Kepler asteroseismic targets using our high-resolution (R>20000) spectroscopic observations; these parameters will then be used to compute asteroseismic models of these stars and to interpret the Kepler light curves.We use the method of cross correlation to measure the radial velocity (RV) of our targets, while atmospheric parameters are derived using the ROTFIT code and spectral synthesis method.
- ID:
- ivo://CDS.VizieR/J/A+A/590/A112
- Title:
- Kepler-539 CAFE radial velocity measurements
- Short Name:
- J/A+A/590/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We confirm the planetary nature of Kepler-539 b (aka Kepler object of interest K00372.01), a giant transiting exoplanet orbiting a solar-analogue G2V star. The mass of Kepler-539 b was accurately derived thanks to a series of precise radial velocity measurements obtained with the CAFE spectrograph mounted on the CAHA 2.2-m telescope. A simultaneous fit of the radial-velocity data and Kepler photometry revealed that Kepler-539 b is a dense Jupiter-like planet with a mass of Mp=0.97M_Jup_ and a radius of Rp=0.747R_Jup_, making a complete circular revolution around its parent star in 125.6-days. The semi-major axis of the orbit is roughly 0.5au, implying that the planet is at 0.45au from the habitable zone. By analysing the mid-transit times of the 12 transit events of Kepler-539 b recorded by the Kepler spacecraft, we found a clear modulated transit time variation (TTV), which is attributable to the presence of a planet c in a wider orbit. The few timings available do not allow us to precisely estimate the properties of Kepler-539 c and our analysis suggests that it has a mass between 1.2 and 3.6 M_Jup_, revolving on a very eccentric orbit (0.4<e<0.6) with a period larger than 1000-days. The high eccentricity of planet c is the probable cause of the TTV modulation of planet b. The analysis of the CAFE spectra revealed a relatively high photospheric lithium content, A(Li)=2.48dex, which, together with both a gyrochronological and isochronal analysis, suggests that the parent star is relatively young.
- ID:
- ivo://CDS.VizieR/J/MNRAS/456/2636
- Title:
- Kepler-10 chemical composition
- Short Name:
- J/MNRAS/456/2636
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundance studies of the Sun and solar twins have demonstrated that the solar composition of refractory elements is depleted when compared to volatile elements, which could be due to the formation of terrestrial planets. In order to further examine this scenario, we conducted a line-by-line differential chemical abundance analysis of the terrestrial planet host Kepler-10 and 14 of its stellar twins. Stellar parameters and elemental abundances of Kepler-10 and its stellar twins were obtained with very high precision using a strictly differential analysis of high quality Canada-France-Hawaii Telescope, Hobby-Eberly Telescope and Magellan spectra. When compared to the majority of thick disc twins, Kepler-10 shows a depletion in the refractory elements relative to the volatile elements, which could be due to the formation of terrestrial planets in the Kepler-10 system. The average abundance pattern corresponds to ~13 Earth masses, while the two known planets in Kepler-10 system have a combined ~20 Earth masses. For two of the eight thick disc twins, however, no depletion patterns are found. Although our results demonstrate that several factors [e.g. planet signature, stellar age, stellar birth location and Galactic chemical evolution (GCE)] could lead to or affect abundance trends with condensation temperature, we find that the trends give further support for the planetary signature hypothesis.
- ID:
- ivo://CDS.VizieR/J/MNRAS/409/1470
- Title:
- Kepler compact pulsator candidates
- Short Name:
- J/MNRAS/409/1470
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the first two quarters of a survey to search for pulsations in compact stellar objects with the Kepler spacecraft. The survey sample and the various methods applied in its compilation are described, and spectroscopic observations are presented to separate the objects into accurate classes. From the Kepler photometry we clearly identify nine compact pulsators and a number of interesting binary stars.
