SEMINARIO: “The Eastern Edge of the Kappa Ori cluster” – Ignazio Pillitteri (INAF Osservatorio Astronomico di Palermo)
May 2 @ 15:30 – 16:30
SEMINARIO: "The Eastern Edge of the Kappa Ori cluster" - Ignazio Pillitteri (INAF Osservatorio Astronomico di Palermo)
Orion is a forgery of young stars, composed of several groups and associations that span different ages  (1-15 Myr) distances (350-450 pc) and masses (from BDs to O type stars). X-rays can be used to infer distances of groups of young stars and thus the spatial structure of the Orion complex.  Exploring the synergy of IR and X-ray observations, I present the first results from a recent XMM observation of a group
of young stellar objects around V1818 Ori. This is a follow up devoted to explore the eastern edge of a ring of dust around Kappa Ori(a B0 V star) that embeds groups of YSOs to the west of the star itself. My preliminary analysis shows that also the group of V1818 Ori belongs to  the Kappa Ori cluster at 250 pc and is unrelated to the Mon R2 region to which it has been associated so far.
Seminario esopianeti – Darius Modirrousta-Galian
Jan 21 @ 11:30 – 13:00

Very Hot Super-Earths with an Atmosphere: A Model Explaining Their Paradoxical Existence

The aim of this research is to constrain the interior structures and evolutions of hot super-Earths, particularly that of 55 Cancri e. Herewith, we propose an alternative model for the paradoxical nature of small, hot super-Earths with atmospheres. Our model does not require these bodies to contain large quantities of ices in order to account for their low densities, which has been a subject of dispute considering their high surface temperatures and the potentially strong internal heat processes such as tidal flexing or radiogenic heating. The first aspect of our research involved calculating the total H2 reservoir in 55 Cancri e which is ~ 2×1023 kg (0.04 M). We then encountered a theoretical enigma since the UV and X-Ray induced mass loss should have been strong enough to evaporate the atmosphere billions of years ago, which is inconsistent with astronomical data showing a currently plentiful atmosphere. This issue can be completely avoided by showing that for a tidally locked setup, the mass loss rates on the night-side are negligible thus allowing the planet to maintain a H2-rich atmosphere above half its surface. In the case of 55 Cancri e, it became tidally locked approximately 50 ± 250 Myrs after it formed implying that from that moment onwards the radius and mass of the body changed negligibly. Prior to this time mass loss rates were very strong and approximately homogeneous which when modelled, showed that 55 Cancri e was born as a Neptunian-or-Jovian-type exoplanet. Finally, we propose that the bimodal distribution in exoplanet radii may be the result of two different evolutionary paths; one where a super-Earth loses all of its atmosphere before it becomes tidally locked (resulting in the peak at ~ 1.3 R), and the other when super-Earths become tidally locked before losing their atmosphere allowing them to maintain it (resulting in the other peak at ~ 2.4 R).