Ultra-hot Jupiters present a unique opportunity to understand the physics and chemistry of planets at extreme conditions. WASP-12b stands out as an archetype of this class of exoplanets. We performed ...comprehensive analyses of the transits, occultations, and phase curves of WASP-12b by combining new CHEOPS observations with previous TESS and Spitzer data to measure the planet's tidal deformation, atmospheric properties, and orbital decay rate. The planet was modeled as a triaxial ellipsoid parameterized by the second-order fluid Love number, \(h_2\), which quantifies its radial deformation and provides insight into the interior structure. We measured the tidal deformation of WASP-12b and estimated a Love number of \(h_2=1.55_{-0.49}^{+0.45}\) (at 3.2\(\sigma\)) from its phase curve. We measured occultation depths of \(333\pm24\)ppm and \(493\pm29\)ppm in the CHEOPS and TESS bands, respectively, while the dayside emission spectrum indicates that CHEOPS and TESS probe similar pressure levels in the atmosphere at a temperature of 2900K. We also estimated low geometric albedos of \(0.086\pm0.017\) and \(0.01\pm0.023\) in the CHEOPS and TESS passbands, respectively, suggesting the absence of reflective clouds in the dayside of the WASP-12b. The CHEOPS occultations do not show strong evidence for variability in the dayside atmosphere of the planet. Finally, we refine the orbital decay rate by 12% to a value of -30.23\(\pm\)0.82 ms/yr. WASP-12b becomes the second exoplanet, after WASP-103b, for which the Love number has been measured (at 3\(sigma\)) from the effect of tidal deformation in the light curve. However, constraining the core mass fraction of the planet requires measuring \(h_2\) with a higher precision. This can be achieved with high signal-to-noise observations with JWST since the phase curve amplitude, and consequently the induced tidal deformation effect, is higher in the infrared.
HD 139139 (a.k.a. 'The Random Transiter') is a star that exhibited enigmatic transit-like features with no apparent periodicity in K2 data. The shallow depth of the events (\(\sim\)200 ppm -- ...equivalent to transiting objects with radii of \(\sim\)1.5 R\(_\oplus\) in front of a Sun-like star), and their non-periodicity, constitutes a challenge for the photometric follow-up of this star. The goal of this study is to confirm with independent measurements the presence of shallow, non-periodic transit-like features on this object. We performed observations with CHEOPS, for a total accumulated time of 12.75 d, distributed in visits of roughly 20 h in two observing campaigns in years 2021 and 2022. The precision of the data is sufficient to detect 150 ppm features with durations longer than 1.5 h. We use the duration and times of the events seen in the K2 curve to estimate how many should have been detected in our campaigns, under the assumption that their behaviour during the CHEOPS observations would be the same as in the K2 data of 2017. We do not detect events with depths larger than 150 ppm in our data set. If the frequency, depth, and duration of the events were the same as in the K2 campaign, we estimate the probability of having missed all events due to our limited observing window would be 4.8 %. We suggest three different scenarios to explain our results: 1) Our observing window was not long enough, and the events were missed with the estimated 4.8 % probability. 2) The events recorded in the K2 observations were time critical, and the mechanism producing them was either not active in the 2021 and 2022 campaigns or created shallower events under our detectability level. 3) The enigmatic events in the K2 data are the result of an unidentified and infrequent instrumental noise in the original data set or its data treatment.
Nature Astronomy, Volume 5, Pages 775-787, June 2021 Exoplanets transiting bright nearby stars are key objects for advancing our
knowledge of planetary formation and evolution. The wealth of photons ...from the
host star gives detailed access to the atmospheric, interior, and orbital
properties of the planetary companions. $\nu^2$ Lupi (HD 136352) is a naked-eye
($V = 5.78$) Sun-like star that was discovered to host three low-mass planets
with orbital periods of 11.6, 27.6, and 107.6 days via radial velocity
monitoring (Udry et al. 2019). The two inner planets (b and c) were recently
found to transit (Kane et al. 2020), prompting a photometric follow-up by the
brand-new $CHaracterising\:ExOPlanets\:Satellite\:(CHEOPS)$. Here, we report
that the outer planet d is also transiting, and measure its radius and mass to
be $2.56\pm0.09$ $R_{\oplus}$ and $8.82\pm0.94$ $M_{\oplus}$, respectively.
With its bright Sun-like star, long period, and mild irradiation ($\sim$5.7
times the irradiation of Earth), $\nu^2$ Lupi d unlocks a completely new region
in the parameter space of exoplanets amenable to detailed characterization. We
refine the properties of all three planets: planet b likely has a rocky mostly
dry composition, while planets c and d seem to have retained small
hydrogen-helium envelopes and a possibly large water fraction. This diversity
of planetary compositions makes the $\nu^2$ Lupi system an excellent laboratory
for testing formation and evolution models of low-mass planets.
Observations of metal absorption systems in the spectra of distant quasars allow to constrain a possible variation of the fine-structure constant throughout the history of the Universe. Such a test ...poses utmost demands on the wavelength accuracy and previous studies were limited by systematics in the spectrograph wavelength calibration. A substantial advance in the field is therefore expected from the new ultra-stable high-resolution spectrograph Espresso, recently installed at the VLT. In preparation of the fundamental physics related part of the Espresso GTO program, we present a thorough assessment of the Espresso wavelength accuracy and identify possible systematics at each of the different steps involved in the wavelength calibration process. Most importantly, we compare the default wavelength solution, based on the combination of Thorium-Argon arc lamp spectra and a Fabry-Pérot interferometer, to the fully independent calibration obtained from a laser frequency comb. We find wavelength-dependent discrepancies of up to 24m/s. This substantially exceeds the photon noise and highlights the presence of different sources of systematics, which we characterize in detail as part of this study. Nevertheless, our study demonstrates the outstanding accuracy of Espresso with respect to previously used spectrographs and we show that constraints of a relative change of the fine-structure constant at the \(10^{-6}\) level can be obtained with Espresso without being limited by wavelength calibration systematics.
We present a software solution for processing recordings of honeybee brain activity in real time. In the honeybee brain, odors elicit spatio-temporal activity patterns that encode odor identity. ...These patterns of neural activity in units called glomeruli can be recorded by calcium imaging with fluorescent dyes, but so far glomerulus segmentation was only possible offline, making interactive experiments impossible. Our main contribution is an adaptive algorithm for image processing, along with a fast implementation for the graphics processing unit that enables semantic segmentation in real time. Semantics is based on the temporal dimension, relying on the fact that time series of pixels within a glomerulus are correlated. We evaluate our software on reference data, demonstrate applicability in a biological experiment, and provide free source code. This paves the way for interactive experiments where neural units can be selected online based on their past activity.
Exoplanets transiting bright nearby stars are key objects for advancing our knowledge of planetary formation and evolution. The wealth of photons from the host star gives detailed access to the ...atmospheric, interior, and orbital properties of the planetary companions. \(\nu^2\) Lupi (HD 136352) is a naked-eye (\(V = 5.78\)) Sun-like star that was discovered to host three low-mass planets with orbital periods of 11.6, 27.6, and 107.6 days via radial velocity monitoring (Udry et al. 2019). The two inner planets (b and c) were recently found to transit (Kane et al. 2020), prompting a photometric follow-up by the brand-new \(CHaracterising\:ExOPlanets\:Satellite\:(CHEOPS)\). Here, we report that the outer planet d is also transiting, and measure its radius and mass to be \(2.56\pm0.09\) \(R_{\oplus}\) and \(8.82\pm0.94\) \(M_{\oplus}\), respectively. With its bright Sun-like star, long period, and mild irradiation (\(\sim\)5.7 times the irradiation of Earth), \(\nu^2\) Lupi d unlocks a completely new region in the parameter space of exoplanets amenable to detailed characterization. We refine the properties of all three planets: planet b likely has a rocky mostly dry composition, while planets c and d seem to have retained small hydrogen-helium envelopes and a possibly large water fraction. This diversity of planetary compositions makes the \(\nu^2\) Lupi system an excellent laboratory for testing formation and evolution models of low-mass planets.
Direct AMS radiocarbon dates of around 31 ka BP (Wild et al., 2005) for several well preserved crania and other human specimens from Mladeč, Czech Republic, confirm their association with the ...Aurignacian. This material, which thus represents the earliest modern European remains with archaeological associations, has long featured in discussions of regional continuity or gene flow from Neanderthal into early Cro-Magnon populations. Here, the four most complete Mladeč crania are compared with Neanderthal fossils in metrical characters of the frontofacial region. Both univariate and multivariate analyses show no evidence of Neanderthal affinities, and thus of Neanderthal-derived genes.
We present a new flare star, which was discovered during our survey on a selected field at the edge of the Pleiades cluster. The field was observed in the period 2007 - 2010 with three different ...CCD-cameras at the University Observatory Jena with telescopes from 25 to 90 cm. The flare duration is almost one hour with an amplitude in the R-band of about 1.08 mag. The location of the flare star in a color-magnitude diagram is consistent with age and distance of the Pleiades. In the optical PSF of the flare star there are two 2MASS objects (unresolved in most images in the optical Jena PSF), so it is not yet known which one of them is responsible for this flare. The BVRIJHK colors yield spectral types of M1 and M2 with extinction being A_V=0.231+/-0.024 mag and A_V=0.266+/-0.020 for those two stars, consistent with the Pleiades cluster.
We report on observation and determination of rotational periods of ten weak-line T Tauri stars in the Cepheus-Cassiopeia star-forming region. Observations were carried out with the ...Cassegrain-Teleskop-Kamera (CTK) at University Observatory Jena between 2007 June and 2008 May. The periods obtained range between 0.49 d and 5.7 d, typical for weak-line and post T Tauri stars.