Related papers: No escaping helium from 55 Cnc e
We present new, high-sensitivity sub-millimeter observations towards 55 Cancri, a nearby G8 star with one, or possibly two, known planetary companion(s). Our 850 $\mu$m map, obtained with the SCUBA instrument on the James Clerk Maxwell…
The study of exoplanetary atmospheres is key to understand the differences between their physical, chemical and dynamical processes. Up to now, the bulk of atmospheric characterization analysis has been conducted on transiting planets. On…
Hydrodynamic escape can strip the envelopes of close-in exoplanets, but most observations of atmospheric mass loss to date have been confined to planets orbiting K and M dwarfs. A growing body of detections of atmospheric escape from…
Atmospheric escape has been detected from the exoplanet HD 209458b through transit observations of the hydrogen Lyman-alpha line. Here we present spectrally resolved Lyman-alpha transit observations of the exoplanet HD 189733b at two…
The near-infrared helium triplet line is a powerful tool for studying atmospheric escape processes of close-in exoplanets, especially irradiated gas giants. Line profile fitting provides direct insight into the mechanisms driving…
We have detected HI 21cm line absorption by the Warm Neutral Medium (WNM) using the Westerbork Synthesis Radio Telescope. The absorption was detected toward Cygnus A at LSR velocities of -40 and -70 km s^{-1}. These two velocity ranges were…
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 by dense H/He envelopes or contain deep H2O oceans also…
When transiting their host stars, hot Jupiters absorb about 10% of the light in the wings of the stellar Lyman-alpha emission line. The absorption occurs at wavelengths Doppler-shifted from line center by +/- 100 km/s - larger than the…
Direct and statistical observational evidences suggest that photoevaporation is important in eroding the atmosphere of sub-Neptune planets. We construct full hydrodynamic simulations, coupled with consistent thermochemistry and ray-tracing…
Absorption in the stellar Lyman-$\alpha$ (Ly-$\alpha$) line observed during the transit of the extrasolar planet HD 209458b reveals high velocity atomic hydrogen at great distances from the planet. This has been interpreted as hydrogen…
There is evidence that the transiting planet HD 209458b has a large exosphere of neutral hydrogen, based on a 15% decrement in Lyman-alpha flux that was observed by Vidal-Madjar et al. during transits. Here we report upper limits on H-alpha…
The bolometric radiation from a central body is potentially a powerful driver of atmospheric escape from planets or satellites. When heated above their equilibrium temperatures those satellites, due to their low surface gravity, are be…
For the first time, the helium abundance relative to hydrogen (He/H), which relied on direct measurements of the electron temperature, has been derived in the narrow line regions (NLRs) from a local sample of Seyfert 2 nuclei. In view of…
Absorption of high-energy radiation in planetary thermospheres is believed to lead to the formation of planetary winds. The resulting mass-loss rates can affect the evolution, particularly of small gas planets. We present 1D, spherically…
We present new near-infrared (1.1-micron) observations of the circumstellar environment of the planet-bearing star 55 Cancri. With these Hubble Space Telescope images we are unable to confirm the observation of bright scattered radiation at…
Extrasolar super-Earths (1-10 M$_{\earth}$) are likely to exist with a wide range of atmospheres. Some super-Earths may be able to retain massive hydrogen-rich atmospheres. Others might never accumulate hydrogen or experience significant…
Four transits of the planet orbiting the star HD209458 were observed with the STIS spectrograph on board HST. The wavelength domain (1180-1710A) includes HI as well as CI, CII, CIV, NV, OI, SI, SiII, SiIII and SiIV lines. During the…
Primary cosmic-ray elemental spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment since 2004. The third CREAM payload (CREAM-III) flew for 29 days during the 2007-2008 Antarctic season.…
Over the past decade, observations of giant exoplanets (Jupiter-size) have provided key insights into their atmospheres, but the properties of lower-mass exoplanets (sub-Neptune) remain largely unconstrained because of the challenges of…
We use the super Earth 55 Cnc e as a case study to address an observable effect of tidal heating. We investigate whether planet-planet interactions can force the eccentricity of this planet to a level affecting the eclipse depth observed…