We have found a dramatic change in the spectra of late-type M dwarfs at wavelengths shorter than 0.75μm. Comparisons with synthetic spectra illustrate that this change is well explained by the presence of dust. It thus seems that a substantial part of the long-standing discrepancies between late-type M dwarf models and observations arises from dust as recently proposed by Tsuji, Ohnaka & Aoki (...

Hot methane spectra are important in environments ranging from flames to the atmospheres of cool stars and exoplanets. A new spectroscopic line list, 10to10, for (12)CH4 containing almost 10 billion transitions is presented. This comprehensive line list covers a broad spectroscopic range and is applicable for temperatures up to 1,500 K. Previous methane data are incomplete, leading to underesti...

Spectroscopic observations of 48 emission-line objects of M 33 have been obtained with the multi-object, wide field, fibre spectrograph AF2/WYFFOS at the 4.2m WHT telescope (La Palma, Spain). Line intensities and logarithmic extinction, cβ, are presented for 42 objects. Their location in the Sabbadin & D’Odorico diagnostic diagram (Hα/[S ii] vs Hα/[N ii]) suggests that >70% of the candidates ar...

WE STAND ON A GREAT DIVIDE in the detection and study of exoplanets. On one side of this divide are the hundreds of known massive exoplanets, with measured densities and atmospheric temperatures for a handful of the hottest exoplanets. On the other side of the divide lies the possibility, as yet unrealized, of detecting and characterizing a true Earth analogue—an Earth-like planet (a planet of ...

Planets that form beyond the snow line with too little mass to seed rapid gas accretion (. 10 M⊕) should be rich in volatile ices like H2O and NH3. Some of these planets should migrate inward by interacting with a circumstellar disk or with other planets. Such objects can retain their volatiles for billions of years or longer at ∼ 1 AU as their atmospheres undergo slow hydrodynamic escape. Thes...

The physical mechanism underlying ENSO’s phase locking to the seasonal cycle is examined in three parameter regimes: the fast-SST limit, the fast-wave limit, and the mixed SST–wave dynamics regime. The seasonal cycle is imposed on simple ordinary differential equation models for each physical regime either as a seasonal ocean– atmosphere coupling strength obtained from the model of Zebiak and C...

By combining diamond-anvil-cell and laser-driven shock wave techniques, we produced dense He samples up to 1.5 g/cm(3) at temperatures reaching 60 kK. Optical measurements of reflectivity and temperature show that electronic conduction in He at these conditions is temperature-activated (semiconducting). A fit to the data suggests that the mobility gap closes with increasing density, and that ho...

Transiting planet discoveries have yielded a plethora of information regarding the internal structure and atmospheres of extra-solar planets. These discoveries have been restricted to the low-periastron distance regime due to the bias inherent in the geometric transit probability. Monitoring known radial velocity planets at predicted transit times is a proven method of detecting transits, and p...

In this paper we discuss themorphology of two bipolar planetary nebulae (PNe) based on broad-band (ESO/SERC) and narrow-band ([O iii] and Hα) images. At first sight both objects are similar and show two pronounced bright knots – the usual signature of a torus seen edge-on. We demonstrate though that the two objects are not two of a kind at this point but are rather representing two different st...

Despite numerous efforts, the transition from Asymptotic Giant Branch (AGB) stars to Planetary Nebulae (PN) is a poorly understood phase of stellar evolution. We have therefore carried out interferometric (VLA) radio observations of a sample of hot post-AGB stars, selected on the basis of their optical and infrared properties. Ten sources out of the 16 observed were detected. This indicates tha...