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22441. Transit timing variations on Qatar-1
ID:
ivo://CDS.VizieR/J/A+A/555/A92
Title:
Transit timing variations on Qatar-1
Short Name:
J/A+A/555/A92
Date:
21 Oct 2021
Publisher:
CDS
Description:
Variations in the timing of transiting exoplanets provide a powerful tool detecting additional planets in the system. Thus, the aim of this paper is to discuss the plausibility of transit timing variations on the Qatar-1 system by means of primary transit light curves analysis. Furthermore, we provide an interpretation of the timing variation. We observed Qatar-1 between March 2011 and October 2012 using the 1.2m OLT telescope in Germany and the 0.6m PTST telescope in Spain. We present 26 primary transits of the hot Jupiter Qatar-1b. In total, our light curves cover a baseline of 18 months. We also refine the ephemeris of Qatar-1b, which we find to be T0=2456157.42204+/-0.0001BJD_TDB_ and P=1.4200246+/-0.0000007 days, and improve the system orbital parameters.
22442. Transmission Spectroscopy Metric of exoplanets
ID:
ivo://CDS.VizieR/J/AJ/159/239
Title:
Transmission Spectroscopy Metric of exoplanets
Short Name:
J/AJ/159/239
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recent years have seen increasing interest in the characterization of sub-Neptune-sized planets because of their prevalence in the Galaxy, contrasted with their absence in our solar system. HD97658 is one of the brightest stars hosting a planet of this kind, and we present the transmission spectrum of this planet by combining four Hubble Space Telescope transits, 12 Spitzer/IRAC transits, and eight Microvariability and Oscillations of Stars Telescope (MOST) transits of this system. Our transmission spectrum has a higher signal-to-noise ratio than those from previous works, and the result suggests that the slight increase in transit depth from wavelength 1.1-1.7{mu}m reported in previous works on the transmission spectrum of this planet is likely systematic. Nonetheless, our atmospheric modeling results are inconclusive, as no model provides an excellent match to our data. Nonetheless, we find that atmospheres with high C/O ratios (C/O~>0.8) and metallicities of ~>100 solar metallicity are favored. We combine the mid-transit times from all of the new Spitzer and MOST observations and obtain an updated orbital period of P=9.489295{+/-}0.000005, with a best-fit transit time center at T0=2456361.80690{+/-}0.00038(BJD). No transit timing variations are found in this system. We also present new measurements of the stellar rotation period (34{+/-}2days) and stellar activity cycle (9.6yr) of the host star HD97658. Finally, we calculate and rank the Transmission Spectroscopy Metric of all confirmed planets cooler than 1000K and with sizes between 1R_{Earth}_ and 4R_{Earth}_. We find that at least a third of small planets cooler than 1000K can be well characterized using James Webb Space Telescope, and of those, HD97658b is ranked fifth, meaning that it remains a high-priority target for atmospheric characterization.
22443. Transmission spectroscopy of HAT-P-32b
ID:
ivo://CDS.VizieR/J/A+A/590/A100
Title:
Transmission spectroscopy of HAT-P-32b
Short Name:
J/A+A/590/A100
Date:
21 Oct 2021
Publisher:
CDS
Description:
We obtained low-resolution, multi-object spectra of the planet host star HAT-P-32 and multiple comparison stars during a transit event of HAT-P-32b. The spectral flux was binned in 62 narrow channels from 3300 to 10000{AA} and used to create differential photometric light curves. These light curves were analysed for a wavelength dependence of the effective planetary radius.
22444. Transmission spectrum of Venus
ID:
ivo://CDS.VizieR/J/A+A/537/L2
Title:
Transmission spectrum of Venus
Short Name:
J/A+A/537/L2
Date:
21 Oct 2021
Publisher:
CDS
Description:
On 5-6 June 2012, Venus will be transiting the Sun for the last time before 2117. This event is an unique opportunity to assess the feasibility of the atmospheric characterisation of Earth-size exoplanets near the habitable zone with the transmission spectroscopy technique and provide an invaluable proxy for the atmosphere of such a planet. In this letter, we provide a theoretical transmission spectrum of the atmosphere of Venus that could be tested with spectroscopic observations during the 2012 transit. This is done using radiative transfer across Venus' atmosphere, with inputs from in-situ missions such as Venus Express and theoretical models. The transmission spectrum covers a range of 0.1-5m and probes the limb between 70 and 150km in altitude. It is dominated in UV by carbon dioxide absorption producing a broad transit signal of ~20ppm as seen from Earth, and from 0.2 to 2.7m by Mie extinction (~5ppm at 0.8m) caused by droplets of sulfuric acid composing an upper haze layer above the main deck of clouds. These features are not expected for a terrestrial exoplanet and could help discriminating an Earth-like habitable world from a cytherean planet.
22445. Trapezium Multiple Systems
ID:
ivo://CDS.VizieR/I/134
Title:
Trapezium Multiple Systems
Short Name:
I/134
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
22446. TRAPPIST-1 analogue stars TESS light curves
ID:
ivo://CDS.VizieR/J/A+A/650/A138
Title:
TRAPPIST-1 analogue stars TESS light curves
Short Name:
J/A+A/650/A138
Date:
22 Feb 2022
Publisher:
CDS
Description:
As more exoplanets are being discovered around ultracool dwarfs, understanding their magnetic activity - and the implications for habitability - is of prime importance. To find stellar flares and photometric signatures related to starspots, continuous monitoring is necessary, which can be achieved with spaceborn observatories like the Transiting Exoplanet Survey Satellite (TESS). We present an analysis of TRAPPIST-1 like ultracool dwarfs with TESS full- frame image photometry from the first two years of the primary mission. A volume-limited sample up to 50pc is constructed consisting of 339 stars closer than 0.5mag to TRAPPIST-1 on the Gaia colour-magnitude diagram. The 30-min cadence TESS light curves of 248 stars were analysed, searching for flares and rotational modulation caused by starspots. The composite flare frequency distribution of the 94 identified flares shows a power law index similar to TRAPPIST-1, and contains flares up to E_TESS_=3*10^33^erg. Rotational periods shorter than 5 days were determined for 42 stars, sampling the regime of fast rotators. The ages of 88 stars from the sample were estimated using kinematic information. A weak correlation between rotational period and age is observed, which is consistent with magnetic braking.
22447. TRAPPIST-1 best-fit parameters
ID:
ivo://CDS.VizieR/J/A+A/658/A170
Title:
TRAPPIST-1 best-fit parameters
Short Name:
J/A+A/658/A170
Date:
22 Feb 2022
Publisher:
CDS
Description:
We analyze solutions drawn from the recently published posterior distribution of the TRAPPIST-1 system, which consists of seven Earth-size planets appearing to be in a resonant chain around a red dwarf. We show that all the planets are simultaneously in 2-planet and 3-planet resonances, apart from the innermost pair for which the 2-planet resonant angles circulate. By means of a frequency analysis, we highlight that the transit-timing variation (TTV) signals possess a series of common periods varying from days to decades, which are also present in the variations of the dynamical variables of the system. Shorter periods (e.g., the TTVs characteristic timescale of 1.3yr) are associated with 2-planet mean-motion resonances, while longer periods arise from 3-planet resonances. By use of N-body simulations with migration forces, we explore the origin of the resonant chain of TRAPPIST-1 and find that for particular disc conditions, a chain of resonances -- similar to the observed one -- can be formed which accurately reproduces the observed TTVs. Our analysis suggests that while the 4-yr collected data of observations hold key information on the 2-planet resonant dynamics, further monitoring of TRAPPIST-1 will soon provide signatures of three-body resonances, in particular the 3.3 and 5.1yr periodicities expected for the current best-fit solution. Additional observations would help to assess whether the innermost pair of planets is indeed resonant (its proximity to the 8:5 resonance being challenging to explain), and therefore give additional constraints on formation scenarios.
22448. TRAPPIST-1 h NIR spectrum
ID:
ivo://CDS.VizieR/J/A+A/658/A133
Title:
TRAPPIST-1 h NIR spectrum
Short Name:
J/A+A/658/A133
Date:
22 Feb 2022
Publisher:
CDS
Description:
The TRAPPIST-1 planetary system is favorable for transmission spectroscopy and offers the unique opportunity to study rocky-planets with possibly non-primary envelopes. We present here the transmission spectrum of the seventh planet of the TRAPPIST-1 system, TRAPPIST-1 h (R_P_=0.752R_{Earth}_, Teq=173K) using Hubble Space Telescope (HST), Wide Field Camera 3 Grism 141 (WFC3/G141) data. Our purpose is to reduce the HST observations of the seventh planet of TRAPPIST-1 system and by testing simple atmospheric hypothesis put new constraint on the composition and the nature of the planet. First we extracted and corrected the raw data to obtain a transmission spectrum in the Near-IR band (1.1-1.7um). TRAPPIST-1 is a cold M-dwarf and its activity could affect the transmission spectrum. We correct for stellar modulations using three different stellar contamination models, while some fit better the data, they are statistically not significant and the conclusion remains unchanged concerning the presence or not of an atmosphere. Finally, using a Bayesian atmospheric retrieval code we put new constraints on the atmosphere composition of TRAPPIST-1h. According to the retrieval analysis, there is no evidence of molecular absorption in the Near-InfraRed (NIR) spectrum. This suggests the presence of a high cloud deck or a layer of photochemical hazes in a primary atmosphere or a secondary atmosphere dominated by heavy species like nitrogen. This result could even be the consequence of the lack of an atmosphere as the spectrum is better fitted using a flat-line. Variations of transit depth around 1.3um are likely due to remaining scattering noise and results are not improved while changing the spectral resolution. TRAPPIST-1 h has probably lost its atmosphere or possesses a layer of clouds and hazes blocking the NIR signal. We can not distinguish yet between a primary cloudy or a secondary clear envelope using HST/WFC3 data but we can reject, in most cases with more than 3{sigma} confidence, the hypothesis of a clear atmosphere dominated by hydrogen and helium. By testing forced secondary atmospheric scenario, we find that a CO-rich atmosphere (i.e with a volume mixing ratio of 0.2) is one of the best fit to the spectrum with a Bayes Factor of 1.01 corresponding to a 2.1{sigma} detection.
22449. TRAPPIST monitoring of comet C/2012 F6 (Lemmon)
ID:
ivo://CDS.VizieR/J/A+A/574/A38
Title:
TRAPPIST monitoring of comet C/2012 F6 (Lemmon)
Short Name:
J/A+A/574/A38
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of the long-term narrowband photometry and imaging monitoring of comet C/2012 F6 (Lemmon) with the robotic TRAPPIST telescope (La Silla observatory). Observations covered 52 nights pre- and post-perihelion between December 11, 2012 and June 11, 2013. We followed the evolution of the OH, NH, CN, C_3_ and C_2_ production rates computed with the Haser model as well as the evolution of the A({theta})f_{rho}_ parameter as a proxy for the dust production. All five gas species display similar slopes for the heliocentric dependence. An asymmetry about perihelion is observed, the rate of brightening being steeper than the rate of fading. The chemical composition of the comet's coma is changing slightly along the orbit: the relative abundance of C_2_ to CN is decreasing for heliocentric distances larger than 1.4AU while the C_3_ to CN ratio is constant during our observations. The behavior of the dust is different from that of the gas, the slope of the heliocentric dependence becoming steeper in early February, correlated to a change of the visual lightcurve slope. However, the dust color does not vary during the observations. The application of several enhancement techniques on the images revealed structures in the CN, C3 and C2 images. These features imply the existence of one or several active zone(s) on the comet nucleus. The shape of the structures is similar in those three filters and changes from a roughly hourglass shape in December and January to a corkscrew shape in February and March. The structures in the continuum filters (sampling the dust) are not correlated to those observed for the gas. During several full nights in February, we observed changes in the CN and C2 structures repeating periodically due to the nucleus rotation, our derived rotational period being of 9.52+/-0.05 hours.
22450. TRAPPIST-South UCD Transit Survey
ID:
ivo://CDS.VizieR/J/MNRAS/497/3790
Title:
TRAPPIST-South UCD Transit Survey
Short Name:
J/MNRAS/497/3790
Date:
21 Oct 2021
Publisher:
CDS
Description:
We conducted a global analysis of the TRAPPIST Ultra-Cool Dwarf Transit Survey - a prototype of the SPECULOOS transit search conducted with the TRAPPIST-South robotic telescope in Chile from 2011 to 2017 - to estimate the occurrence rate of close-in planets such as TRAPPIST-1b orbiting ultra-cool dwarfs. For this purpose, the photometric data of 40 nearby ultra-cool dwarfs were reanalysed in a self-consistent and fully automated manner starting from the raw images. The pipeline developed specifically for this task generates differential light curves, removes non-planetary photometric features and stellar variability, and searches for transits. It identifies the transits of TRAPPIST-1b and TRAPPIST-1c without any human intervention. To test the pipeline and the potential output of similar surveys, we injected planetary transits into the light curves on a star-by-star basis and tested whether the pipeline is able to detect them. The achieved photometric precision enables us to identify Earth-sized planets orbiting ultra-cool dwarfs as validated by the injection tests. Our planet-injection simulation further suggests a lower limit of 10 per cent on the occurrence rate of planets similar to TRAPPIST-1b with a radius between 1 and 1.3 R_{Earth}_ and the orbital period between 1.4 and 1.8d.

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