scholarly journals The Kepler-11 system: evolution of the stellar high-energy emission and initial planetary atmospheric mass fractions

2019 ◽  
Vol 632 ◽  
pp. A65 ◽  
Author(s):  
D. Kubyshkina ◽  
L. Fossati ◽  
A. J. Mustill ◽  
P. E. Cubillos ◽  
M. B. Davies ◽  
...  
Keyword(s):  
Mass Loss ◽  
Extreme Ultraviolet ◽  
High Energy ◽  
X Ray ◽  
System Parameters ◽  
The Past ◽  
Energy Emission ◽  
Mass Fractions ◽  
High Energy Emission ◽  
Atmospheric Mass

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 during the early stages of evolution. We recently developed a framework to exploit this connection and enable us to recover the past evolution of the stellar high-energy emission from the present-day properties of its planets, if the latter retain some remnants of their primordial hydrogen-dominated atmospheres. Furthermore, the framework can also provide constraints on planetary initial atmospheric mass fractions. The constraints on the output parameters improve when more planets can be simultaneously analysed. This makes the Kepler-11 system, which hosts six planets with bulk densities between 0.66 and 2.45 g cm−3, an ideal target. Our results indicate that the star has likely evolved as a slow rotator (slower than 85% of the stars with similar masses), corresponding to a high-energy emission at 150 Myr of between 1 and 10 times that of the current Sun. We also constrain the initial atmospheric mass fractions for the planets, obtaining a lower limit of 4.1% for planet c, a range of 3.7–5.3% for planet d, a range of 11.1–14% for planet e, a range of 1–15.6% for planet f, and a range of 4.7–8.7% for planet g assuming a disc dispersal time of 1 Myr. For planet b, the range remains poorly constrained. Our framework also suggests slightly higher masses for planets b, c, and f than have been suggested based on transit timing variation measurements. We coupled our results with published planet atmosphere accretion models to obtain a temperature (at 0.25 AU, the location of planet f) and dispersal time of the protoplanetary disc of 550 K and 1 Myr, although these results may be affected by inconsistencies in the adopted system parameters. This work shows that our framework is capable of constraining important properties of planet formation models.

scholarly journals EUV irradiation of exoplanet atmospheres occurs on Gyr time-scales

2020 ◽  
Vol 501 (1) ◽  
pp. L28-L32
Author(s):  
George W King ◽  
Peter J Wheatley
Keyword(s):  
Mass Loss ◽  
Time Scales ◽  
High Energy ◽  
Planetary Atmospheres ◽  
X Rays ◽  
X Ray ◽  
Atmospheric Escape ◽  
Euv Emission ◽  
Energy Emission ◽  
High Energy Emission

ABSTRACT Exoplanet atmospheres are known to be vulnerable to mass-loss through irradiation by stellar X-ray and extreme-ultraviolet (EUV) emission. We investigate how this high-energy irradiation varies with time by combining an empirical relation describing stellar X-ray emission with a second relation describing the ratio of solar X-ray to EUV emission. In contrast to assumptions commonly made when modelling atmospheric escape, we find that the decline in stellar EUV emission is much slower than in X-rays, and that the total EUV irradiation of planetary atmospheres is dominated by emission after the saturated phase of high-energy emission (which lasts around 100 Myr after the formation of the star). The EUV spectrum also becomes much softer during this slow decline. Furthermore, we find that the total combined X-ray and EUV emission of stars occurs mostly after the saturated phase. Our results suggest that models of atmospheric escape that focus on the saturated phase of high-energy emission are oversimplified, and when considering the evolution of planetary atmospheres it is necessary to follow EUV-driven escape on Gyr time-scales. This may make it more difficult to use stellar age to separate the effects of photoevaporation and core-powered mass-loss when considering the origin of the planet radius valley.

scholarly journals ON THE INTERACTION OF JETS WITH STELLAR WINDS IN MASSIVE X–RAY BINARIES

2010 ◽  
Vol 19 (06) ◽  
pp. 791-796
Author(s):  
MANEL PERUCHO ◽  
VALENTÍ BOSCH-RAMON ◽  
DMITRY KHANGULYAN
Keyword(s):  
Stellar Wind ◽  
Binary Star ◽  
Three Dimensional ◽  
High Energy ◽  
X Ray ◽  
Energy Emission ◽  
Injection Power ◽  
Radio Band ◽  
High Energy Emission ◽  
X Ray Binaries

We present the first three-dimensional simulations of the evolution of a microquasar jet inside the binary star system. The aim is to study the interaction of these jets with the stellar wind from a massive companion and the possible locations of high-energy emission sites. We have simulated two jets with different injection power in order to give a hint on the minimum power required for the jet to escape the system and become visible in larger scales. In the setup, we include a massive star wind filling the grid through which the jet evolves. We show that jets should have powers of the order of 1037 erg s-1 or more in order not to be destroyed by the stellar wind. The jet–wind interaction results in regions in which high-energy emission could be produced. These results imply the possible existence of a population of X–ray binaries undetected in the radio band due to jet disruption inside the region dominated by the stellar wind.

scholarly journals PSR B0656+14: Combined Optical, X-ray & EUV Studies

2000 ◽  
Vol 177 ◽  
pp. 299-300
Author(s):  
Aaron Golden ◽  
Andy Shearer ◽  
Jerry Edelstein
Keyword(s):  
High Energy ◽  
Archival Data ◽  
Polar Cap ◽  
Optical Photometry ◽  
X Ray ◽  
Energy Emission ◽  
High Energy Emission

AbstractPSR B0656+14’s high energy emission is consistent with that of combined magnetospheric and thermal (surface & polar cap) emission. Uncertainties with the radio-derived distance and X-ray instrumentation sensitivities complicate a definitive thermal characterisation however. A re-analysis of combined ROSAT/EUVE archival data in conjunction with integrated & phase-resolved optical photometry is shown to constrain this characterisation.

scholarly journals X-ray Variability of Blazars

2002 ◽  
Vol 19 (1) ◽  
pp. 49-54 ◽  
Author(s):  
Elena Pian
Keyword(s):  
Energy Range ◽  
High Energy ◽  
Space Missions ◽  
Present Review ◽  
Wide Energy Range ◽  
Spectral Variability ◽  
X Ray ◽  
Energy Emission ◽  
Wide Energy ◽  
High Energy Emission

AbstractCritical progress in our understanding of high energy emission from AGN has been determined in the last 10 years by X-ray monitoring campaigns with many space missions, notably ROSAT, ASCA, RXTE, BeppoSAX, and XMM, often in conjunction with observations at other frequencies. The emphasis of the present review is on recent findings about X-ray variability of blazars. Among AGN, these exhibit the largest amplitude variations of the X-ray emission, often well correlated with variations at higher energies (GeV and TeV radiation). The accurate sampling of the X-ray spectra over more than three decades in energy, made possible by the wide energy range of BeppoSAX, has also shown strong spectral variability in blazar active states, suggesting extreme electron energies and leading to the identification of a class of ‘extreme synchrotron’ sources.

scholarly journals Slow motion pulsar wind nebulae

2021 ◽  
Vol 2103 (1) ◽  
pp. 012020
Author(s):  
K P Levenfish ◽  
G A Ponomaryov ◽  
A E Petrov ◽  
A M Bykov ◽  
A M Krassilchtchikov
Keyword(s):  
Time Scales ◽  
Relative Motion ◽  
Slow Motion ◽  
High Energy ◽  
Pulsar Wind Nebulae ◽  
Extra Time ◽  
X Ray ◽  
Energy Emission ◽  
Pulsar Wind ◽  
High Energy Emission

Abstract We show that even the slow (subsonic) motion of pulsar wind nebulae (PWNe) relative to an ambient matter has a significant impact on their observables. The motion changes the appearance of nebulae on X-ray images, comparing to what would be observed for a nebula at rest. Accounting for the relative motion is necessary to avoid misinterpretation of the structure of the nebulae when analyzing their X-ray morphology. The motion also introduces some extra time scales in variability of non-thermal high-energy emission of PWNe and allows to reproduce a number of their structures that are not explained by stationary nebula models.

scholarly journals CORRELATED X-RAY AND VERY HIGH ENERGY EMISSION IN THE GAMMA-RAY BINARY LS I +61 303

2009 ◽  
Vol 706 (1) ◽  
pp. L27-L32 ◽  
Author(s):  
H. Anderhub ◽  
L. A. Antonelli ◽  
P. Antoranz ◽  
M. Backes ◽  
C. Baixeras ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
X Ray ◽  
Energy Emission ◽  
Very High Energy ◽  
High Energy Emission ◽  
Very High

scholarly journals The high-energy emission from HD 93129A near periastron

2020 ◽  
Vol 494 (4) ◽  
pp. 6043-6052
Author(s):  
S del Palacio ◽  
F García ◽  
D Altamirano ◽  
R H Barbá ◽  
V Bosch-Ramon ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Energy ◽  
X Ray ◽  
Energy Emission ◽  
Collision Region ◽  
Upper Limits ◽  
The Galaxy ◽  
Radiative Model ◽  
Γ Ray ◽  
High Energy Emission

ABSTRACT We conducted an observational campaign towards one of the most massive and luminous colliding wind binaries in the Galaxy, HD 93129A, close to its periastron passage in 2018. During this time the source was predicted to be in its maximum of high-energy emission. Here we present our data analysis from the X-ray satellites Chandra and NuSTAR and the γ-ray satellite AGILE. High-energy emission coincident with HD 93129A was detected in the X-ray band up to ∼18 keV, whereas in the γ-ray band only upper limits were obtained. We interpret the derived fluxes using a non-thermal radiative model for the wind-collision region. We establish a conservative upper limit for the fraction of the wind kinetic power that is converted into relativistic electron acceleration, fNT,e < 0.02. In addition, we set a lower limit for the magnetic field in the wind-collision region as BWCR > 0.3 G. We also argue a putative interpretation of the emission from which we estimate fNT,e ≈ 0.006 and BWCR ≈ 0.5 G. We conclude that multiwavelength, dedicated observing campaigns during carefully selected epochs are a powerful tool for characterizing the relativistic particle content and magnetic field intensity in colliding wind binaries.

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