INFLUENCE OF STELLAR FLARES ON THE CHEMICAL COMPOSITION OF EXOPLANETS AND SPECTRA
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More than 3000 exoplanets have been detected so far, and more and more spectroscopic observations of exoplanets are performed. Future instruments are eagerly awaited as they will be able to provide spectroscopic data with a greater accuracy and sensitivity than what is currently available. An important aspect to consider is temporal stellar atmospheric disturbances that can influence the planetary composition, and hence spectra, and potentially can lead to incorrect assumptions about the steady-state atmospheric composition of the planet. We focus on perturbations that come from the host star in the form of flare events that significantly increase the photon flux impingement on the exoplanet atmosphere. In some cases, and particularly for M stars, this sudden increase may last for several hours. We aim at answering the question to what extent a stellar flare is able to modify the chemical composition of the planetary atmosphere and, therefore influence the resulting spectra. We use a 1D thermo-photochemical model to study the neutral atmospheric composition of two hypothetic planets located around the star AD Leo. This active star has already been observed during a flare. We use the spectroscopic data from this flare event to simulate the evolution of the chemical composition of the atmospheres of the two hypothetic planets. We compute synthetic spectra to evaluate the implications for observations. The increase of the incoming photon flux affects the chemical abundances of some important species down to altitudes associated with an atmospheric pressure of 1 bar, that can lead to variations in planetary spectra if performed during transit.Keywords:
Flare
The colloquium "Detection and Dynamics of Transiting Exoplanets" was held at the Observatoire de Haute-Provence and discussed the status of transiting exoplanet investigations in a 4.5 day meeting. Topics addressed ranged from planet detection, a discussion on planet composition and interior structure, atmospheres of hot-Jupiter planets, up to the effect of tides and the dynamical evolution of planetary systems. Here, I give a summary of the recent developments of transiting planet detections and investigations discussed at this meeting.
Jupiter (rocket family)
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"An Introduction to Planets. Ours and Others; From Earth to Exoplanets, by Therese Encrenaz." Contemporary Physics, 56(4), p. 511
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A NEW CONCEPT FOR DIRECT IMAGING AND SPECTRAL CHARACTERIZATION OF EXOPLANETS IN MULTI-PLANET SYSTEMS
We present a novel method for direct detection and characterization of exoplanets from space. This method uses four collecting telescopes, combined with phase chopping and a spectrometer, with observations on only a few baselines rather than on a continuously rotated baseline. Focusing on the contiguous wavelength spectra of typical exoplanets, the (u, v) plane can be simultaneously and uniformly filled by recording the spectrally resolved signal. This concept allows us to perfectly remove speckles from reconstructed images. For a target comprising a star and multiple planets, observations on three baselines are sufficient to extract the position and spectrum of each planet. Our simulations show that this new method allows us to detect an analog Earth around a Sun-like star at 10 pc and to acquire its spectrum over the wavelength range from 8 to 19 {\mu}m with a high spectral resolution of 100. This method allows us to fully characterize an analog Earth and to similarly characterize each planet in multi-planet systems.
Direct imaging
Spectral resolution
Position (finance)
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ABSTRACT Optical and ultraviolet spectroscopy can enable the assessment of the physical conditions characterizing a stellar flare atmosphere and thereby potentially elucidate the possible radiative and hydrodynamic transport mechanisms operative during stellar flares. In this review, I present illustrative examples of the spectroscopic diagnostic techniques that can be applied to the analysis of stellar flare spectroscopic data and the resulting inferences concerning stellar flare properties for M dwarf flare events.
Flare
Flare star
Ultraviolet
Solar flare
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To test the standard flare model (CSHKP-model), we measured the magnetic-flux change rate in five flare events of different GOES classes using chromospheric/photospheric observations and compared its progression with observed nonthermal flare emission. We calculated the cumulated positive and negative magnetic flux participating in the reconnection process, as well as the total reconnection flux. Finally, we investigated the relations between the total reconnection flux, the GOES class of the events, and the linear velocity of the flare-associated CMEs. Using high-cadence H-alpha and TRACE 1600 A image time-series data and MDI/SOHO magnetograms, we measured the required observables (newly brightened flare area and magnetic-field strength inside this area). RHESSI and INTEGRAL hard X-ray time profiles in nonthermal energy bands were used as observable proxies for the flare-energy release rate. We detected strong temporal correlations between the derived magnetic-flux change rate and the observed nonthermal emission of all events. The cumulated positive and negative fluxes, with flux ratios of between 0.64 and 1.35, were almost equivalent to each other. Total reconnection fluxes ranged between 1.8 x 10^21 Mx for the weakest event (GOES class B9.5) and 15.5 x 10^21 Mx for the most energetic one (GOES class X17.2). The amount of magnetic flux participating in the reconnection process was higher in more energetic events than in weaker ones. Flares with more reconnection flux were associated with faster CMEs.
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Solar flare
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In this work, we present transit timing variations detected for the exoplanet TrES-5b. To obtain the necessary amount of photometric data for this exoplanet, we have organized an international campaign to search for exoplanets based on the Transit Timing Variation method (TTV) and as a result of this we collected 30 new light curves, 15 light curves from the Exoplanet Transit Database (ETD) and 8 light curves from the literature for the timing analysis of the exoplanet TrES-5b. We have detected timing variations with a semi-amplitude of A ~ 0.0016 days and a period of P ~ 99 days. We carried out the N-body modeling based on the three-body problem. The detected perturbation of TrES-5b may be caused by a second exoplanet in the TrES-5 system. We have calculated the possible mass and resonance of the object: M ~ 0.24MJup at a 1:2 Resonance.
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Planets are common around Sun-like stars. ‘Exoplanets’ examines this type of planet. The first discovery of an exoplanet was made in 1995, and hundreds of exoplanets are now known to exist. Exoplanets have been found by detecting slight changes in a star's radial velocity, and by looking for ‘transits’ (a tiny fraction of a star's light that is cut off during the passage of an exoplanet in front of it) using Earth-based and space-based automated telescopes. What do we actually know about exoplanets? Are they named? How do we image them? How many multiple exoplanet systems are there, and is it possible that life could thrive on exoplanets?
Direct imaging
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We present the results of analyzing the XMM-Newton data obtained in 2001 November 7-8. A flare is observed simultaneously in X-ray and UV together with a quiescence. We find that during the flare event X-ray flux varies with UV with no significant time lag, indicating a close correlation of flux variation for X-ray and UV flares. An upper limit of the lag is estimated to be ~1 minute. From a timing analysis for X-ray data, we find that both pulsed and unpulsed flux increase clearly as the flare advances in the entire energy band 0.15-10 keV. The net increase of pulsed flux to the quiescence is, however, small and corresponds to about 3%-4% of the increase in unpulsed flux, confirming that a flux variation of flare in AE Aqr is dominated by unpulsed X-rays. A spectral analysis reveals that the energy spectrum is similar to that of the quiescence at the beginning of the flare, but the spectrum becomes harder as the flare advances. Based on these results, we discuss the current issues that need to be clarified, e.g., the possible flaring site and the mass accretion problem of the white dwarf. We also discuss the flare properties obtained in this study.
Flare
Accretion disc
Solar flare
Flare star
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Flare
Line (geometry)
Photon flux
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Exoplanets are planets orbiting a star other than the Sun. These exoplanets may exist in many different forms, such as a hot Jupiter and super earth. Detecting is the first step to further studying the properties of these exoplanets. In this paper, based on data of star Qatar-1 gathered from July 22nd 2022, a light flux curve is developed during the period of 04:28 - 07:01 UTC through which the star is observed. The presence of an exoplanet, presumably Qatar-1b, is revealed in the analyzing results of the collected data, showing the validity of the transit approach for exoplanet detection. By using this approach, exoplanets planets can be discovered for further research in regards to potentially habitable and/or resource-rich exoplanets.
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