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Optical spectroscopic observations sometimes show asymmetrically broadened wings and/or transient extra-emissions in chromospheric lines during or shortly after flares. Such events appear most commonly on active M dwarfs. These signatures could be due to prominence eruptions, which are closely related to CMEs on the Sun. Here we present an updated semi-empirical model which combines predictions of intrinsic stellar CME rates with radiative transfer calculations in the Balmer lines. Although Balmer signatures of (eruptive) prominences are typically dominated by scattering of the incident radiation on the Sun, we find that for M dwarfs the contribution of thermal emission should not be neglected. Its inclusion can lead to modified visibility compared to our previous study which assumed only scattering. Our updated model also predicts that filaments (i.e. prominences located in front of the stellar disk) can appear in emission for a wide range of plasma parameters on M dwarfs, in contrast to the Sun. This finding is consistent with existing observations of M dwarfs, which show typically blue asymmetries/blue-shifted line components in emission, but reports of absorption signatures are uncommon., Acknowledgments: Austrian Science Fund (FWF): P30949-N36, I 5711-N; Czech Science Foundation 19-17102S, 22-34841S; 'Excellence Initiative - Research University' 2020-2026 at University of Wrocław project No. BPIDUB.4610.96.2021.KG., {"references":["Heinzel, P. (2015), ASSL, 415, 103","Labrosse, N. et al. (2010), SSR, 151, 243","Leitzinger, M. et al. (2022), Poster at Cool Stars 21, doi:10.5281/zenodo.7404528","Leitzinger, M. et al. (2022), MNRAS, 513, 6058","Odert, P. et al. (2020), MNRAS, 494, 3766","Odert, P. et al. (2017), MNRAS, 472, 876"]}

Stellar flares and coronal mass ejections (CMEs) can have serious effects on their surroundings: they can erode or completely destroy atmospheres of orbiting planets over time and also have high importance in stellar evolution. Most of the stellar CME detections in the literature are single events found serendipitously sparse for statistical investigation. We present a search in archive spectra of dwarf stars from solar-like objects to M-dwarfs aimed to find a large number of stellar CMEs suitable for statistical analysis. For M-dwarfs, we found event rates that are lower than we could expect from the solar paradigm, and no convincing events for solar-like stars. What can be behind this low number of events? Can high-resolution solar spectra help us to learn more on stellar CMEs?, This work was supported by the Hungarian National Research, Development and Innovation Office grant NKFIH (OTKA) K-131508 and by the NKFIH grant 2019-2.1.11-TÉT-2019-00056. Authors acknowledge the financial support of the Austrian-Hungarian Action Foundation (101öu13, 104öu2). L.K. acknowledges the financial support of the Hungarian National Research, Development and Innovation Office grant NKFIH PD-134784. L.K. and K.V. are Bolyai János Research Fellows.

The influence of the hydrogen hydrodynamic upper atmosphere escape, driven by the solar soft X-ray and extreme ultraviolet radiation (XUV) flux, on an expected magma ocean outgassed steam atmosphere of early Venus is studied. By assuming that the young Sun was either a weak or moderate active young G star, we estimated the water loss from a hydrogen dominated thermosphere due to the absorption of the solar XUV flux and the precipitation of solar wind produced energetic hydrogen atoms (ENAs). The production of ENAs and their interaction with the hydrodynamic extended upper atmosphere, including collision-related feedback processes, have been calculated by means of Monte Carlo models. ENAs that collide in the upper atmosphere deposit their energy and heat the surrounding gas mainly above the main XUV energy deposition layer. It is shown that precipitating ENAs modify the thermal structure of the upper atmosphere, but the enhancement of the thermal escape rates caused by these energetic hydrogen atoms is negligible. Our results also indicate that the majority of oxygen arising from dissociated H$_2$O molecules is left behind during the first 100 Myr. It is thus suggested that the main part of the remaining oxygen has been absorbed by crustal oxidation., 6 figures and 2 tables

International audience; While Venus and Earth were accumulating mass within the solar nebular these protoplanets also captured significant hydrogen dominated atmospheres by picking up gas from the circumstellar disk during the formation of the Solar System (e.g. Stökl et al. 2016). These primordial atmospheres were then quickly lost by hydrodynamic escape after the disk dissipated. After a short but efficient boil-off phase the EUV-driven hydrodynamic flow of H atoms dragged heavier elements with it at different rates, leading to changes in their isotopic and elemental ratios (Zahnle and Kasting 1986, Hunten et al. 1987, Odert et al. 2018), which is reflected in the present-day atmospheric noble gas isotope and elemental ratios of Venus and Earth. Depending on the disk lifetime and the initial composition of the protoplanets, we find that the atmospheric 36Ar/38Ar, 20Ne/22Ne, and bulk K/U ratios observed for both planets can be best explained if the Sun was born between a weakly and moderately active star and if Venus and Earth had grown to 85-100% and 53-58% respectively of their current masses by the time the nebula gas dissipated approximately 3.5 Myr after formation of the Sun. If proto-Earth accreted its mass from 60% volatile poor ureilite-like and 40% carbonatious chondritic-like material (Schiller et al. 2018) then the planet must have been grown to about 80% of its final mass as long as it was surrounded by the escaping primordial atmosphere ( 7 Myr). Our results are therefore in agreement with a fast accretion of thermally-processed disk material into asteroidal bodies and/or planetary embryos, as well as Hafnium-Tungsten chronometric fast accretion scenarios of the proto-Earth (e.g. Yu & Jacobsen 2011), as well as a noble gas origin based on a mixture of primitive meteoroids and a small remnant of the proto-solar nebula (Marty 2012). This also indicates that a significant amount of the terrestrial building blocks were delivered from behind the so-called snow line early-on.

Hydrogen-dominated atmospheres of hot exoplanets expand and escape due to the intense heating by the X-ray and extreme ultraviolet (XUV) irradiation of their host stars. Excess absorption of neutral hydrogen has been observed in the Ly$��$ line during transits of several close-in exoplanets, indicating such extended atmospheres. For the hot Jupiter HD 189733b, this absorption shows temporal variability. Variations in stellar XUV emission and/or stellar wind conditions have been invoked to explain this effect. We apply a 1D hydrodynamic upper atmosphere model and a 3D MHD stellar wind flow model to study the effect of variations of the stellar XUV and wind conditions on the neutral hydrogen distribution, including the production of energetic neutral atoms (ENAs), and the related Ly$��$ transit signature. We obtain comparable, albeit slightly higher Ly$��$ absorption as observed in 2011 with a stellar XUV flux of $1.8\times10^4$ erg cm$^{-2}$ s$^{-1}$, rather typical activity conditions for this star. Flares similar to the one observed 8 h before the transit are unlikely to have caused a significant modulation of the transit signature. The resulting Ly$��$ absorption is dominated by atmospheric broadening, whereas the contribution of ENAs is negligible, as they are formed inside the bow shock from decelerated wind ions that are heated to high temperatures. Thus, within our modeling framework and assumptions, we find an insignificant dependence on the stellar wind parameters. Since the transit absorption can be modeled with typical stellar XUV and wind conditions, it is possible that the non-detection of the absorption in 2010 was affected by less typical stellar activity conditions, such as a very different magnitude and/or shape of the star's spectral XUV emission, or temporal/spatial variations in Ly$��$ affecting the determination of the transit absorption., 22 pages, 19 figures, 4 tables; A&A, published

We modeled the transit signatures in the Lya line of a putative Earth-sized planet orbiting in the HZ of the M dwarf GJ436. We estimated the transit depth in the Lya line for an exo-Earth with three types of atmospheres: a hydrogen-dominated atmosphere, a nitrogen-dominated atmosphere, and a nitrogen-dominated atmosphere with an amount of hydrogen equal to that of the Earth. We calculated the in-transit absorption they would produce in the Lya line. We applied it to the out-of-transit Lya observations of GJ 436 obtained by the HST and compared the calculated in-transit absorption with observational uncertainties to determine if it would be detectable. To validate the model, we also used our method to simulate the deep absorption signature observed during the transit of GJ 436b and showed that our model is capable of reproducing the observations. We used a DSMC code to model the planetary exospheres. The code includes several species and traces neutral particles and ions. At the lower boundary of the DSMC model we assumed an atmosphere density, temperature, and velocity obtained with a hydrodynamic model for the lower atmosphere. We showed that for a small rocky Earth-like planet orbiting in the HZ of GJ436 only the hydrogen-dominated atmosphere is marginally detectable with the STIS/HST. Neither a pure nitrogen atmosphere nor a nitrogen-dominated atmosphere with an Earth-like hydrogen concentration in the upper atmosphere are detectable. We also showed that the Lya observations of GJ436b can be reproduced reasonably well assuming a hydrogen-dominated atmosphere, both in the blue and red wings of the Lya line, which indicates that warm Neptune-like planets are a suitable target for Lya observations. Terrestrial planets can be observed in the Lya line if they orbit very nearby stars, or if several observational visits are available., 17 pages, 12 figures, accepted for publication in Astronomy & Astrophysics

The NASA Kepler mission revealed the existence of a large variety of planets very different from what we know from the Solar System. Among them, a large number of planets was found in the range between Earth and Neptune (e.g. [1]), with a large spread in average densities (e.g. [2-4]). These planets are easier to detect and characterize in comparison to Earth-like planets, making them primary targets for a number of upcoming missions such as CHEOPS [5], TESS [6], JWST [7], PLATO [8], and ARIEL [9]. As part of the work carried out in support to the scientific preparations for the CHEOPS mission, we have assembled a large grid of upper planetary atmosphere models covering super-Earths hosting hydrogen-dominated atmospheres and orbiting early M- to late F-type main-sequence stars. The planetary mass ranges between 1 and 39 Earth masses (up to twice Neptune mass), while the radii cover the 1 to 10 Earth radii (up to 2.5 Neptune radius) range. The equilibrium temperature of the planets spans from 300 to 2000 K. For each stellar mass, we considered three distinct values of the high-energy (XUV) stellar fluxes, which cover roughly the interval from a chromospherically active to a quiet star. The base physical model is an upgraded version of the model from [10], that is a 1D hydrodynamic model of an XUV-heated atmosphere accounting for hydrogen dissociation, recombination and ionization, Lα- and H3+-cooling, and X-ray heating. The boundaries are the planet photosphere and Roche lobe. To allow the computation of a large grid, the XUV stellar spectrum is simplified to two wavelength points: 60 nm and 5 nm for the emission in the extreme ultraviolet (EUV) and X-ray spectral ranges, respectively. The grid of models consists of about 7000 points and provides the height profiles of the main atmospheric parameters, namely temperature, velocity, bulk density, and hydrogen species fractions, from which we compute the atmospheric escape rates and other relevant quantities. We further developed an interpolation routine allowing one to obtain the output of the model grid for any planet lying inside the grid boundaries. We coupled the interpolation routine with a planetary structure code providing the atmospheric mass fractions for any given planet on the basis of the system parameters and basic assumptions [13]. By employing the two codes, we compute planetary atmosphere evolution tracks for a number of known planets. We further employ the MESA Isochrones and Stellar Tracks (MIST; [11]) to account for changes of stellar temperature, radius (controlling the planetary equilibrium temperature), and bolometric luminosity (involved in the computation of the stellar XUV flux [12]). We present the modeling scheme, the code upgrades, the model grid, and the interpolation routine. We further show how the current lack of a hydrogen-dominated atmosphere for close-in, high- density super-Earths can be the result of atmospheric escape. We finally apply our simple atmospheric evolution scheme to planets hosting a hydrogen-dominated atmosphere showing how it can lead to further constraining important planetary and stellar properties.

Very long baseline interferometry at millimetre/submillimetre wavelengths (mmVLBI) offers the highest achievable spatial resolution at any wavelength in astronomy. The anticipated inclusion of ALMA as a phased array into a global VLBI network will bring unprecedented sensitivity and a transformational leap in capabilities for mmVLBI. Building on years of pioneering efforts in the US and Europe the ongoing ALMA Phasing Project (APP), a US-led international collaboration with MPIfR-led European contributions, is expected to deliver a beamformer and VLBI capability to ALMA by the end of 2014 (APP: Fish et al. 2013, arXiv:1309.3519). This report focuses on the future use of mmVLBI by the international users community from a European viewpoint. Firstly, it highlights the intense science interest in Europe in future mmVLBI observations as compiled from the responses to a general call to the European community for future research projects. A wide range of research is presented that includes, amongst others: - Imaging the event horizon of the black hole at the centre of the Galaxy - Testing the theory of General Relativity an/or searching for alternative theories - Studying the origin of AGN jets and jet formation - Cosmological evolution of galaxies and BHs, AGN feedback - Masers in the Milky Way (in stars and star-forming regions) - Extragalactic emission lines and astro-chemistry - Redshifted absorption lines in distant galaxies and study of the ISM and circumnuclear gas - Pulsars, neutron stars, X-ray binaries - Testing cosmology - Testing fundamental physical constants

Very long baseline interferometry at millimetre/submillimetre wavelengths (mmVLBI) offers the highest achievable spatial resolution at any wavelength in astronomy. The anticipated inclusion of ALMA as a phased array into a global VLBI network will bring unprecedented sensitivity and a transformational leap in capabilities for mmVLBI. Building on years of pioneering efforts in the US and Europe the ongoing ALMA Phasing Project (APP), a US-led international collaboration with MPIfR-led European contributions, is expected to deliver a beamformer and VLBI capability to ALMA by the end of 2014 (APP: Fish et al. 2013, arXiv:1309.3519). This report focuses on the future use of mmVLBI by the international users community from a European viewpoint. Firstly, it highlights the intense science interest in Europe in future mmVLBI observations as compiled from the responses to a general call to the European community for future research projects. A wide range of research is presented that includes, amongst others: - Imaging the event horizon of the black hole at the centre of the Galaxy - Testing the theory of General Relativity an/or searching for alternative theories - Studying the origin of AGN jets and jet formation - Cosmological evolution of galaxies and BHs, AGN feedback - Masers in the Milky Way (in stars and star-forming regions) - Extragalactic emission lines and astro-chemistry - Redshifted absorption lines in distant galaxies and study of the ISM and circumnuclear gas - Pulsars, neutron stars, X-ray binaries - Testing cosmology - Testing fundamental physical constants

Transit observations of HD 209458b in the stellar Lyman-$��$ (Ly$��$) line revealed strong absorption in both blue and red wings of the line interpreted as hydrogen atoms escaping from the planet's exosphere at high velocities. The following sources for the absorption were suggested: acceleration by the stellar radiation pressure, natural spectral line broadening, charge exchange with stellar wind. We reproduce the observation by means of modelling that includes all aforementioned processes. Our results support a stellar wind with a velocity of $\approx400$ km$\times$s$^{-1}$ at the time of the observation and a planetary magnetic moment of $\approx 1.6 \times 10^{26}$ A$\times$m$^2$., This is the author's version of the work. It is posted here by permission of the AAAS for non-commercial research use only. The definitive version was published in Science, vol. 346, p. 981, 21 November 2014, DOI: 10.1126/science.1257829. 3 pages, 3 figures

Very long baseline interferometry at millimetre/submillimetre wavelengths (mmVLBI) offers the highest achievable spatial resolution at any wavelength in astronomy. The anticipated inclusion of ALMA as a phased array into a global VLBI network will bring unprecedented sensitivity and a transformational leap in capabilities for mmVLBI. Building on years of pioneering efforts in the US and Europe the ongoing ALMA Phasing Project (APP), a US-led international collaboration with MPIfR-led European contributions, is expected to deliver a beamformer and VLBI capability to ALMA by the end of 2014 (APP: Fish et al. 2013, arXiv:1309.3519). This report focuses on the future use of mmVLBI by the international users community from a European viewpoint. Firstly, it highlights the intense science interest in Europe in future mmVLBI observations as compiled from the responses to a general call to the European community for future research projects. A wide range of research is presented that includes, amongst others: - Imaging the event horizon of the black hole at the centre of the Galaxy - Testing the theory of General Relativity an/or searching for alternative theories - Studying the origin of AGN jets and jet formation - Cosmological evolution of galaxies and BHs, AGN feedback - Masers in the Milky Way (in stars and star-forming regions) - Extragalactic emission lines and astro-chemistry - Redshifted absorption lines in distant galaxies and study of the ISM and circumnuclear gas - Pulsars, neutron stars, X-ray binaries - Testing cosmology - Testing fundamental physical constants

International audience; The evolution and escape of the martian atmosphere and the planet's water inventory can be separated into an early and late evolutionary epoch. The first epoch started from the planet's origin and lasted ˜500 Myr. Because of the high EUV flux of the young Sun and Mars' low gravity it was accompanied by hydrodynamic blow-off of hydrogen and strong thermal escape rates of dragged heavier species such as O and C atoms. After the main part of the protoatmosphere was lost, impact-related volatiles and mantle outgassing may have resulted in accumulation of a secondary CO2 atmosphere of a few tens to a few hundred mbar around ˜4-4.3 Gyr ago. The evolution of the atmospheric surface pressure and water inventory of such a secondary atmosphere during the second epoch which lasted from the end of the Noachian until today was most likely determined by a complex interplay of various nonthermal atmospheric escape processes, impacts, carbonate precipitation, and serpentinization during the Hesperian and Amazonian epochs which led to the present day surface pressure.

We present a new observational campaign, DWARF, aimed at detection of circumbinary extrasolar planets using the timing of the minima of low-mass eclipsing binaries. The observations will be performed within an extensive network of relatively small to medium-size telescopes with apertures of ~20-200 cm. The starting sample of the objects to be monitored contains (i) low-mass eclipsing binaries with M and K components, (ii) short-period binaries with sdB or sdO component, and (iii) post-common-envelope systems containing a WD, which enable to determine minima with high precision. Since the amplitude of the timing signal increases with the orbital period of an invisible third component, the timescale of project is long, at least 5-10 years. The paper gives simple formulas to estimate suitability of individual eclipsing binaries for the circumbinary planet detection. Intrinsic variability of the binaries (photospheric spots, flares, pulsation etc.) limiting the accuracy of the minima timing is also discussed. The manuscript also describes the best observing strategy and methods to detect cyclic timing variability in the minima times indicating presence of circumbinary planets. First test observation of the selected targets are presented., 12 pages, 2 figures, submitted to Astron. Nachrichten

We present a new observational campaign, Dwarf, aimed at detection of circumbinary extrasolar planets using the timing of the minima of low-mass eclipsing binaries. The observations will be performed within an extensive network of relatively small to medium-size telescopes with apertures of ∼20-200 cm. The starting sample of the objects to be monitored contains (i) low-mass eclipsing binaries with M and K components, (ii) short-period binaries with a sdB or sdO component, and (iii) post-common-envelope systems containing a WD, which enable to determine minima with high precision. Since the amplitude of the timing signal increases with the orbital period of an invisible third component, the timescale of the project is long, at least 5-10 years. The paper gives simple formulas to estimate the suitability of individual eclipsing binaries for the circumbinary planet detection. Intrinsic variability of the binaries (photospheric spots, flares, pulsation etc.) limiting the accuracy of the minima timing is also discussed. The manuscript also describes the best observing strategy and methods to detect cyclic timing variability in the minima times indicating the presence of circumbinary planets. First test observations of the selected targets are presented.

Very long baseline interferometry at millimetre/submillimetre wavelengths (mmVLBI) offers the highest achievable spatial resolution at any wavelength in astronomy. The anticipated inclusion of ALMA as a phased array into a global VLBI network will bring unprecedented sensitivity and a transformational leap in capabilities for mmVLBI. Building on years of pioneering efforts in the US and Europe the ongoing ALMA Phasing Project (APP), a US-led international collaboration with MPIfR-led European contributions, is expected to deliver a beamformer and VLBI capability to ALMA by the end of 2014 (APP: Fish et al. 2013, arXiv:1309.3519). This report focuses on the future use of mmVLBI by the international users community from a European viewpoint. Firstly, it highlights the intense science interest in Europe in future mmVLBI observations as compiled from the responses to a general call to the European community for future research projects. A wide range of research is presented that includes, amongst others: - Imaging the event horizon of the black hole at the centre of the Galaxy - Testing the theory of General Relativity an/or searching for alternative theories - Studying the origin of AGN jets and jet formation - Cosmological evolution of galaxies and BHs, AGN feedback - Masers in the Milky Way (in stars and star-forming regions) - Extragalactic emission lines and astro-chemistry - Redshifted absorption lines in distant galaxies and study of the ISM and circumnuclear gas - Pulsars, neutron stars, X-ray binaries - Testing cosmology - Testing fundamental physical constants, Replaced figures 2 and 3: corrected position SRT. Corrected minor typo in 5.1