Publications (44)
Probing the Blow-Off Criteria of Hydrogen-Rich "Super-Earths"
H. Lammer, N. V. Erkaev, P. Odert +3
The discovery of transiting "super-Earths" with inflated radii and known masses such as Kepler-11b-f, GJ 1214b and 55 Cnc e, indicates that these exoplanets did not lose their nebu…
PLATOSpec: a precise spectrograph in support of space missions
P. Kabáth, M. Skarka, A. Hatzes +42
The upcoming space missions that will characterize exoplanets, such as PLATO and Ariel, will collect huge amounts of data that will need to be complemented with ground-based observ…
Rossby waves and polar spots in rapidly rotating stars: Implications for stellar wind evolution
T. V. Zaqarashvili, R. Oliver, J. L. Ballester +5
Rapidly rotating stars show short-period oscillations in magnetic activity and polar appearance of starspots. The aim of this paper is to study large-scale shallow water waves in t…
The Evolution of Stellar Rotation and the hydrogen atmospheres of habitable-zone Terrestrial Planets
C. P. Johnstone, M. Güdel, A. Stökl +7
Terrestrial planets formed within gaseous protoplanetary disks can accumulate significant hydrogen envelopes. The evolution of such an atmosphere due to XUV driven evaporation depe…
Stellar coronal mass ejections II. Constraints from spectroscopic observations
P. Odert, M. Leitzinger, E. W. Guenther +1
Detections of stellar coronal mass ejections (CMEs) are still rare. Observations of strong Balmer line asymmetries during flare events have been interpreted as being caused by CMEs…
Magma oceans and enhanced volcanism on TRAPPIST-1 planets due to induction heating
K. G. Kislyakova, L. Noack, C. P. Johnstone +6
Low-mass M stars are plentiful in the Universe and often host small, rocky planets detectable with the current instrumentation. Recently, seven small planets have been discovered o…
Effect of stellar wind induced magnetic fields on planetary obstacles of non-magnetized hot Jupiters
N. V. Erkaev, P. Odert, H. Lammer +7
We investigate the interaction between the magnetized stellar wind plasma and the partially ionized hydrodynamic hydrogen outflow from the escaping upper atmosphere of non- or weak…
Indications of stellar prominence oscillations on fast rotating stars: the cases of HK Aqr and PZ Tel
M. Leitzinger, P. Odert, T. V. Zaqarashvili +3
We present the analysis of six nights of spectroscopic monitoring of two young and fast rotating late-type stars, namely the dMe star HK Aqr and the dG/dK star PZ Tel. On both star…
The DWARF project: Eclipsing binaries - precise clocks to discover exoplanets
T. Pribulla, M. VaÅko, M. Ammler - von Eiff +53
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 observation…
Stellar wind interaction and pick-up ion escape of the Kepler-11 "super-Earths"
K. G. Kislyakova, C. P. Johnstone, P. Odert +6
We study the interactions between stellar wind and the extended hydrogen-dominated upper atmospheres of planets and the resulting escape of planetary pick-up ions from the 5 "super…
Origin and Stability of Exomoon Atmospheres - Implications for Habitability
H. Lammer, S. -C. Schiefer, I. Juvan +7
We study the origin and escape of catastrophically outgassed volatiles (HO, CO) from exomoons with Earth-like densities and masses of , and $…
Solar XUV and ENA-driven water loss from early Venus' steam atmosphere
H. I. M. Lichtenegger, K. G. Kislyakova, P. Odert +8
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 outgasse…
The Exosphere as a Boundary: Origin and Evolution of Airless Bodies in the Inner Solar System and Beyond Including Planets with Silicate Atmospheres
H. Lammer, M. Scherf, Y. Ito +6
In this review we discuss all the relevant solar/stellar radiation and plasma parameters and processes that act together in the formation and modification of atmospheres and exosph…
Escape of the martian protoatmosphere and initial water inventory
N. V. Erkaev, H. Lammer, L. Elkins-Tanton +8
Latest research in planet formation indicate that Mars formed within a few million years (Myr) and remained a planetary embryo that never grew to a more massive planet. It can also…
Observations and detectability of young Suns' flaring and CME activity in optical spectra
M. Leitzinger, P. Odert, R. Greimel
The Sun's history is still a subject of interest to modern astrophysics. Observationally constrained CME rates of young solar analogues are still lacking, as those require dedicate…
Transit Ly- signatures of terrestrial planets in the habitable zones of M dwarfs
K. G. Kislyakova, M. Holmström, P. Odert +6
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 ex…
Origin and Loss of nebula-captured hydrogen envelopes from "sub"- to "super-Earths" in the habitable zone of Sun-like stars
H. Lammer, A. Stökl, N. V. Erkaev +6
We investigate the origin and loss of captured hydrogen envelopes from protoplanets between `sub-Earth'-like bodies of 0.1 up to `super-Earths' with 5 in th…
Modification of the radioactive heat budget of Earth-like exoplanets by the loss of primordial atmospheres
N. Erkaev, M. Scherf, O. Herbort +6
The initial abundance of radioactive heat producing isotopes in the interior of a terrestrial planet are important drivers of its thermal evolution and the related tectonics and po…
Escape and fractionation of volatiles and noble gases from Mars-sized planetary embryos and growing protoplanets
P. Odert, H. Lammer, N. V. Erkaev +6
Planetary embryos form protoplanets via mutual collisions, which can lead to the development of magma oceans. During their solidification, large amounts of the mantles' volatile co…
Investigating magnetic activity in very stable stellar magnetic fields: long-term photometric and spectroscopic study of the fully convective M4 dwarf V374 Peg
K. Vida, L. Kriskovics, K. Oláh +8
The ultrafast-rotating () fully convective single M4 dwarf V374 Peg is a well-known laboratory for studying intense stellar activity in a stable magnet…
Loss and fractionation of noble gas isotopes and moderately volatile elements from planetary embryos and early Venus, Earth and Mars
H. Lammer, M. Scherf, H. Kurokawa +12
Here we discuss the current state of knowledge on how atmospheric escape processes can fractionate noble gas isotopes and moderately volatile rock-forming elements that populate pr…
Outgassing History and Escape of the Martian Atmosphere and Water Inventory
H. Lammer, E. Chassefière, Ã. Karatekin +11
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 pla…
Thermal mass loss of protoplanetary cores with hydrogen-dominated atmospheres: The influences of ionization and orbital distance
N. V. Erkaev, H. Lammer, P. Odert +4
We investigate the loss rates of the hydrogen atmospheres of terrestrial planets with a range of masses and orbital distances by assuming a stellar extreme ultraviolet (EUV) lumino…
Stellar Aspects of Habitability: Characterizing Target Stars for Terrestrial Planet Search Missions
L. Kaltenegger, C. Eiroa, I. Ribas +7
In this paper we present and discuss the criteria for selecting potential target stars suitable for the search for Earth like planets, with a special emphasis on the stellar aspect…
Spectroscopic observations of flares and superflares on AU Mic
P. Odert, M. Leitzinger, R. Greimel +13
The young active flare star AU~Mic is the planet host star with the highest flare rate from TESS data. Therefore, it represents an ideal target for dedicated ground-based monitorin…
XUV exposed non-hydrostatic hydrogen-rich upper atmospheres of terrestrial planets. Part I: Atmospheric expansion and thermal escape
N. V. Erkaev, H. Lammer, P. Odert +6
The recently discovered low-density "super-Earths" Kepler-11b, Kepler-11f, Kepler-11d, Kepler-11e, and planets such as GJ 1214b represent most likely planets which are surrounded b…
Magnetic moment and plasma environment of HD 209458b as determined from Ly observations
K. G. Kislyakova, M. Holmström, H. Lammer +2
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…
Stellar Coronal Mass Ejections I. Estimating occurrence frequencies and mass-loss rates
P. Odert, M. Leitzinger, A. Hanslmeier +1
Stellar coronal mass ejections (CMEs) may play an important role in mass- and angular momentum loss of young Sun-like stars. If occurring frequently, they may also have a strong ef…
Supermassive Hot Jupiters Provide More Favourable Conditions for the Generation of Radio Emission via the Cyclotron Maser Instability - A Case Study Based on Tau Bootis b
C. Weber, N. V. Erkaev, V. A. Ivanov +5
We investigate under which conditions supermassive hot Jupiters can sustain source regions for radio emission, and whether this emission could propagate to an observer outside the…
Extreme hydrodynamic atmospheric loss near the critical thermal escape regime
N. V. Erkaev, H. Lammer, P. Odert +2
By considering martian-like planetary embryos inside the habitable zone of solar-like stars we study the behavior of the hydrodynamic atmospheric escape of hydrogen for small value…
On the required mass for exoplanetary radio emission
Jean-Mathias GrieÃmeier, N. V. Erkaev, C. Weber +3
The detection of radio emission from an exoplanet would constitute the best way to determine its magnetic field. Indeed, the presence of a planetary magnetic field is a necessary c…
XUV exposed, non-hydrostatic hydrogen-rich upper atmospheres of terrestrial planets II: Hydrogen coronae and ion escape
K. G. Kislyakova, H. Lammer, M. Holmström +8
We study the interactions between the stellar wind plasma flow of a typical M star, such as GJ 436, and hydrogen-rich upper atmospheres of an Earth-like planet and a "super-Earth"…
A confined dynamo: magnetic activity of the K-dwarf component in the pre-cataclysmic binary system V471 Tauri
Zs. KÅvári, L. Kriskovics, K. Oláh +6
We scrutinize the red dwarf component in the eclipsing binary system V471 Tau in order to unravel relations between different activity layers from the stellar surface through the c…
Identifying the "true" radius of the hot sub-Neptune CoRoT-24b by mass loss modelling
H. Lammer, N. V. Erkaev, L. Fossati +8
For the hot exoplanets CoRoT-24b and CoRoT-24c, observations have provided transit radii R of 3.70.4 R and 4.90.5 R, and masses of 5.…
The Kepler-11 system: evolution of the stellar high-energy emission and {initial planetary} atmospheric mass fractions
D. Kubyshkina, L. Fossati, A. J. Mustill +8
The atmospheres of close-in planets are strongly influenced by mass loss driven by the high-energy (X-ray and extreme ultraviolet, EUV) irradiation of the host star, particularly d…
A census of Coronal Mass Ejections on solar-like stars
M. Leitzinger, P. Odert, R. Greimel +8
Coronal Mass Ejections (CMEs) may have major importance for planetary and stellar evolution. Stellar CME parameters, such as mass and velocity, have yet not been determined statist…
Spectroscopic investigation of the southern late-K/early-M dwarf binary CC Eri
M. Leitzinger, P. Odert, R. Greimel +6
In the recent past investigations of stellar Coronal Mass Ejections (CMEs) and flares/superflares gained special attention because of their relevance for planetary habitability and…
A search for flares and mass ejections on young late-type stars in the open cluster Blanco-1
M. Leitzinger, P. Odert, R. Greimel +5
We present a search for stellar activity (flares and mass ejections) in a sample of 28 stars in the young open cluster Blanco-1. We use optical spectra obtained with ESO's VIMOS mu…
Aeronomical constraints to the minimum mass and maximum radius of hot low-mass planets
L. Fossati, N. V. Erkaev, H. Lammer +7
Stimulated by the discovery of a number of close-in low-density planets, we generalise the Jeans escape parameter taking hydrodynamic and Roche lobe effects into account. We furthe…
Future mmVLBI Research with ALMA: A European vision
R. P. J. Tilanus, T. P. Krichbaum, J. A. Zensus +165
Very long baseline interferometry at millimetre/submillimetre wavelengths (mmVLBI) offers the highest achievable spatial resolution at any wavelength in astronomy. The anticipated…
Flares and superflares on the southern active binary CC Eri
M. Leitzinger, P. Odert, R. Greimel +15
Flares and CMEs are known to be the dominating high-energy phenomena on cool stars. Superflares were thoroughly investigated using broadband photometry predominantly from Kepler, K…
Modeling the Ly transit absorption of the hot Jupiter HD 189733b
P. Odert, N. V. Erkaev, K. G. Kislyakova +7
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 abs…
Impact inducted surface heating by planetesimals on early Mars
T. I. Maindl, R. Dvorak, H. Lammer +7
We investigate the influence of impacts of large planetesimals and small planetary embryos on the early Martian surface on the hydrodynamic escape of an early steam atmosphere that…
Spectroscopy of flares on AU Mic
P. Odert, M. Leitzinger, P. Kabáth +6
Photometric space missions like Kepler and TESS have revealed unprecedented statistics of stellar flares, including the frequent detection of highly energetic superflares. Spectros…