Found 3 talks width keyword molecular data
Understanding the atmospheric and evolutive properties of very low mass stars, brown dwarfs, and gas giant exoplanets have been important challenges for modelers around the world since the discovery of the first brown dwarfs in the Pleiades cluster (Rebolo et al. 1995) and in the field (Nakajima et al. 1995). The early studies of brown dwarfs have provided rich insights into atmospheric physics, with discoveries ranging from cloud formation (Tsuji et al. 1996), methane bands (Oppenheimer et al. 1995) and ammonia bands (Delorme et al. 2008), to the formation of wasi-molecular KI-H2 absorption (Allard et al. 2007), and to disequilibrium chemistry (Yelle & Griffith 2001). New classical 1D models yield spectral energy distribution (SED) that match relatively well despite these complexities. These models have for instance explained the spectral transition from M to L, T and now Y brown dwarf spectral types (Allard et al. 2013). However, in presence of surface inhomogeneities revealed recently for a nearby (2 pc) brown dwarf (Crossfield et al. 2014), the SED may well fit even exactly, but the model parameters could be far from exact, e.g. with the effective temperature by several hundred kelvins too cool in the case of dusty brown dwarfs and young gas giant exoplanets! I will review the progress achieved in reproducing the spectral properties of very low mass stars, brown dwarfs and gas giant exoplanets, and review progress in modeling more accurately their atmospheres using Radiation HydroDynamical (RHD) simulations.
I will present the first Large Millimiter Telescope spectra of 4 nearby galaxies with known high star formation rates. The individual spectra were acquired with the Redshift Search Receiver, a 3 mm spectrograph that covers simultaneously the 3 mm band from 75 to 110 GHz. The spectra show rms temperatures of around 4 mK that allow us to detect not only common molecular species such as CO, HCN, HCO+, HCN, 13CO reported widely in the literature but also other more rare molecular transitions (HC3N, CN, CH3OH, CH3C2H) and even Hydrogen recombination lines (from H39alpha to H42alpha). We are making use of theoretical radiative transfer models to analize these spectra in order to understand the variations of the observed line ratios of different lines in galaxies classified as ultraluminous infrared galaxies where the star formation rate may be as high as 100 solar masses per year. These data will help to understand the physical conditions of the gas in regions that are forming stars very efficiently. The observed line ratios in star forming galaxies are also compared to those galaxies that is known to contain an AGN.
In this talk I will present the first complete 12CO J=3-2 map of M81, observed as part of the Nearby Galaxies Legacy Survey. We have detected nine regions of significant CO emission located at different positions within the spiral arms, and confirmed that the global CO emission in the galaxy is low. Using a new Hα map obtained with the Isaac Newton Telescope and archival data I will discuss a series of topics including the correlation between the molecular gas and star forming regions, the CO (3-2)/(1-0) line ratio, and the amount of hydrogen produced in photo-dissociation regions near the locations where CO J=3-2 was detected.
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- Is gravity the only dark matter interaction that matters in the physics of galaxies?Prof. Jesús Zavala FrancoThursday February 27, 2020 - 10:30 (Aula)
- Astronomical dating of ancient societies in the 2nd millennium BCEDr. Rita GautschyWednesday March 4, 2020 - 10:30 (Aula)