Multiwavelength photometry of the secondary eclipses of extrasolar planets is able to disentangle the reflected and thermally emitted light radiated from the planetary dayside. Based on this, we can ...measure the planetary geometric albedo $A_g$ , which is an indicator of the presence of clouds in the atmosphere, and the recirculation efficiency epsilon , which quantifies the energy transport within the atmosphere. We measure $A_g$ and epsilon for the planet a highly irradiated giant planet with an estimated equilibrium temperature of 2450 K. We analyzed archival spectra and the light curves collected by CHEOPS and TESS to characterize the host refine the ephemeris of the system, and measure the eclipse depth in the passbands of the two telescopes. We measured a marginally significant eclipse depth of 70pm 40 ppm in the TESS passband, and a statistically significant depth of 70pm 20 ppm in the CHEOPS passband. Combining the eclipse-depth measurement in the CHEOPS eff AA$) and TESS eff AA$) passbands, we constrained the dayside brightness temperature of in the 2250-2800 K interval. The geometric albedo 0.1<$ A_g$<0.35 generally supports the picture that giant planets are poorly reflective, while the recirculation efficiency $ makes an interesting laboratory for testing the current heat-recirculation models.
ABSTRACT
We report the discovery of a third planet transiting the star TOI-1260, previously known to host two transiting sub-Neptune planets with orbital periods of 3.127 and 7.493 d, respectively. ...The nature of the third transiting planet with a 16.6-d orbit is supported by ground-based follow-up observations, including time-series photometry, high-angular resolution images, spectroscopy, and archival imagery. Precise photometric monitoring with CHEOPS allows to improve the constraints on the parameters of the system, improving our knowledge on their composition. The improved radii of TOI-1260b and TOI-1260c are $2.36 \pm 0.06 \rm R_{\oplus }$, $2.82 \pm 0.08 \rm R_{\oplus }$, respectively while the newly discovered third planet has a radius of $3.09 \pm 0.09 \rm R_{\oplus }$. The radius uncertainties are in the range of 3 per cent, allowing a precise interpretation of the interior structure of the three planets. Our planet interior composition model suggests that all three planets in the TOI-1260 system contains some fraction of gas. The innermost planet TOI-1260b has most likely lost all of its primordial hydrogen-dominated envelope. Planets c and d were also likely to have experienced significant loss of atmospheric through escape, but to a lesser extent compared to planet b.
Context.
Tidal orbital decay is suspected to occur for hot Jupiters in particular, with the only observationally confirmed case of this being WASP-12b. By examining this effect, information on the ...properties of the host star can be obtained using the so-called stellar modified tidal quality factor
Q
*
′
, which describes the efficiency with which the kinetic energy of the planet is dissipated within the star. This can provide information about the interior of the star.
Aims.
In this study, we aim to improve constraints on the tidal decay of the KELT-9, KELT-16, and WASP-4 systems in order to find evidence for or against the presence of tidal orbital decay. With this, we want to constrain the
Q
*
′
value for each star. In addition, we aim to test the existence of the transit timing variations (TTVs) in the HD 97658 system, which previously favoured a quadratic trend with increasing orbital period.
Methods.
Making use of newly acquired photometric observations from CHEOPS (CHaracterising ExOplanet Satellite) and TESS (Transiting Exoplanet Survey Satellite), combined with archival transit and occultation data, we use Markov chain Monte Carlo (MCMC) algorithms to fit three models to the data, namely a constant-period model, an orbital-decay model, and an apsidal-precession model.
Results.
We find that the KELT-9 system is best described by an apsidal-precession model for now, with an orbital decay trend at over 2
σ
being a possible solution as well. A Keplerian orbit model with a constant orbital period provides the best fit to the transit timings of KELT-16 b because of the scatter and scale of their error bars. The WASP-4 system is best represented by an orbital decay model at a 5
σ
significance, although apsidal precession cannot be ruled out with the present data. For HD 97658 b, using recently acquired transit observations, we find no conclusive evidence for a previously suspected strong quadratic trend in the data.
The planetary system around the naked-eye star v2 Lupi (HD 136352; TOI-2011) is composed of three exoplanets with masses of 4.7, 11.2, and 8.6 Earth masses (M⊕). The TESS and CHEOPS missions revealed ...that all three planets are transiting and have radii straddling the radius gap separating volatile-rich and volatile-poor super-earths. Only a partial transit of planet d had been covered so we re-observed an inferior conjunction of the long-period 8.6 M⊕ exoplanet v2 Lup d with the CHEOPS space telescope. We confirmed its transiting nature by covering its whole 9.1 h transit for the first time. We refined the planet transit ephemeris to P = 107.1361−0.0022+0.0019 days and Tc = 2459009.7759−0.0096+0.0101 BJDTDB, improving by ~40 times on the previously reported transit timing uncertainty. This refined ephemeris will enable further follow-up of this outstanding long-period transiting planet to search for atmospheric signatures or explore the planet's Hill sphere in search for an exomoon. In fact, the CHEOPS observations also cover the transit of a large fraction of the planet's Hill sphere, which is as large as the Earth's, opening the tantalising possibility of catching transiting exomoons. We conducted a search for exomoon signals in this single-epoch light curve but found no conclusive photometric signature of additional transiting bodies larger than Mars. Yet, only a sustained follow-up of v2 Lup d transits will warrant a comprehensive search for a moon around this outstanding exoplanet. Undetrended and detrended light curves are only available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/671/A154
Context. Hot subdwarfs experienced strong mass loss on the red giant branch (RGB) and are now hot and small He-burning objects. These stars constitute excellent opportunities for addressing the ...question of the evolution of exoplanetary systems directly after the RGB phase of evolution. Aims. In this project we aim to perform a transit survey in all available light curves of hot subdwarfs from space-based telescopes (Kepler, K2, TESS, and CHEOPS) with our custom-made pipeline SHERLOCK in order to determine the occurrence rate of planets around these stars as a function of orbital period and planetary radius. We also aim to determine whether planets that were previously engulfed in the envelope of their red giant host star can survive, even partially, as a planetary remnant. Methods. For this first paper, we performed injection-and-recovery tests of synthetic transits for a selection of representative Kepler, K2, and TESS light curves to determine which transiting bodies in terms of object radius and orbital period we will be able to detect with our tools. We also provide estimates for CHEOPS data, which we analyzed with the pycheops package. Results. Transiting objects with a radius ≲1.0 R⊕ can be detected in most of the Kepler, K2, and CHEOPS targets for the shortest orbital periods (1 d and shorter), reaching values as low as ~0.3 R⊕ in the best cases. Sub-Earth-sized bodies are only reached for the brightest TESS targets and for those that were observed in a significant number of sectors. We also give a series of representative results for larger planets at greater distances, which strongly depend on the target magnitude and on the length and quality of the data. Conclusions. The TESS sample will provide the most important statistics for the global aim of measuring the planet occurrence rate around hot subdwarfs. The Kepler, K2, and CHEOPS data will allow us to search for planetary remnants, that is, very close and small (possibly disintegrating) objects.
Direct determination of quasar redshifts de Bruijne, J. H. J.; Reynolds, A. P.; Perryman, M. A. C. ...
Astronomy & astrophysics,
01/2002, Letnik:
381, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We present observations of 11 quasars, selected in the range $z \approx 2.2$–4.1, obtained with ESA's Superconducting Tunnel Junction (STJ) camera on the WHT. Using a single template QSO spectrum, we ...show that we can determine the redshifts of these objects to about 1%. A follow-up spectroscopic observation of one QSO for which our best-fit redshift ($z = 2.976$) differs significantly from the tentative literature value ($z \approx 2.30$) confirms that the latter was incorrect.
STJ observations of the eclipsing polar HU Aqr Bridge, C. M.; Cropper, Mark; Ramsay, Gavin ...
Monthly Notices of the Royal Astronomical Society,
11/2002, Letnik:
336, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Abstract
We apply an eclipse mapping technique to observations of the eclipsing magnetic cataclysmic variable HU Aqr. The observations were made with the S-Cam2 superconducting tunnel junction ...detector at the William Herschel Telescope in 2000 October, providing high signal-to-noise ratio observations with simultaneous spectral and temporal resolution. HU Aqr was in a bright (high accretion) state (V= 14.7) and the stream contributes as much to the overall system brightness as the accretion region on the white dwarf. The stream is modelled assuming accretion is occurring on to only one pole of the white dwarf. We find enhanced brightness towards the accretion region from irradiation and interpret enhanced brightness in the threading region, where the ballistic stream is redirected to follow the magnetic field lines of the white dwarf, as magnetic heating from the stream-field interaction, which is consistent with recent theoretical results. Changes in the stream eclipse profile over one orbital period indicate that the magnetic heating process is unstable.
Focal plane cameras for ESA optical astronomy missions Lumb, D.H.; Rando, N.; Peacock, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2003, Letnik:
513, Številka:
1
Journal Article
Recenzirano
Charge-coupled devices (CCDs) have played an important role in imaging and spectroscopic measurements for visible wavelength astronomy. Their introduction has been largely responsible for driving the ...deployment of 8–10
m class telescopes, and in consequence have revolutionized experimental cosmology. Other scientific initiatives such as planet-finding are rapidly increasing in importance for the astronomical community, and we review two future European Space Agency missions which emphasize such new directions. In each case, we address some detailed design issues for their focal planes, showing how new CCD development activities may satisfy the mission requirements.
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