Found 11 talks width keyword spectroscopy

Tuesday June 30, 2020
Luis Welbanks
Institute of Astronomy (University of Cambridge)


Atmospheric compositions can provide powerful diagnostics of formation and migration histories of planetary systems. In this talk, I will present the results of our latest survey of atmospheric compositions focused on atmospheric abundances of H2O, Na, and K. We employ a sample of 19 exoplanets spanning from cool mini-Neptunes to hot Jupiters, with equilibrium temperatures between ~300 and 2700 K. We employ the latest transmission spectra, new H2 broadened opacities of Na and K, and homogeneous Bayesian retrievals. We confirm detections of H2O in 14 planets and detections of Na and K in 6 planets each. Among our sample, we find a mass-metallicity trend of increasing H2O abundances with decreasing mass, spanning generally substellar values for gas giants and stellar/superstellar for Neptunes and mini-Neptunes. However, the overall trend in H2O abundances, is significantly lower than the mass-metallicity relation for carbon in the solar system giant planets and similar predictions for exoplanets. On the other hand, the Na and K abundances for the gas giants are stellar or superstellar, consistent with each other, and generally consistent with the solar system metallicity trend. The H2O abundances in hot gas giants are likely due to low oxygen abundances relative to other elements rather than low overall metallicities, and provide new constraints on their formation mechanisms. Our results show that the differing trends in the abundances of species argue against the use of chemical equilibrium models with metallicity as one free parameter in atmospheric retrievals, as different elements can be differently enhanced.

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Monday December 3, 2018
Rubén Fedriani
Dublin Institute for Advanced Studies (DIAS)


In contrast with low-mass young stellar objects (LMYSOs), very little is known about high-mass YSOs (HMYSOs). Latest results indicate that HMYSOs might be born in a similar way as LMYSOs, i.e., through disc accretion and jet ejection. HMYSOs are deeply embedded in their parent cloud and are at kpc distance, hindering direct imaging of their accretion discs. Jets then become essential to understand the physical properties of the central source. High-resolution near-IR VLT instruments allow us to study HMYSO jets down to au scales and compare them with the low-mass regime. In this talk, I will present VLT/ISAAC, SINFONI, and CRIRES results on two HMYSOs. Spectro-astrometry is used to retrieve information about the jet down to mas scales (~tens of au at kpc distance). High-resolution spectroscopy allows us to retrieve the kinematic and dynamic properties of the massive jets. Additionally, HST imaging in the [FeII] shows the jet structure close to the star. Finally, these properties are compared with low-mass jets, suggesting that the formation of HMYSOs might be a scaled-up version of their low-mass counterparts, and their properties scale with mass.

Friday November 30, 2018
Prof. Klaus G. Strassmeier


The demand of high-res spectroscopy had seen a tremendous increase after the discovery of exoplanets. Such instruments are now among the standard equipment of nearly every observatory. The latest addition in the zoo is PEPSI, the new bench-mounted fiber-fed and stabilized “Potsdam Echelle Polarimetric and Spectroscopic Instrument” for the 11.8m Large Binocular Telescope (LBT). It covers the entire optical wavelength range from 383 to 914 nm in three exposures at resolutions of either R=λ/Δλ=50,000, 130,000 or 250,000. As of this year, the R=130,000 mode can also be used with two dual-beam Stokes IQUV polarimeters and as such provides another unique capability besides the ultra-high resolution mode. It is also fiber linked to a disk-integration solar telescope and the Vatican Observatory's 1.8m VATT. In this talk I introduce the instrument and focus on first data and results in order to "feel the taste". Among the first targets were the Sun and solar twins, Gaia benchmark stars, Jupiter's Io, planet-host stars with hot Jupiters as well as stars with Earth-sized planets, novae, the ISM, and much more.

Thursday July 9, 2015
Mr. Néstor Espinoza
Pontificia Universidad Católica de Chile


One of the most exciting possibilities enabled by transiting exoplanets is to measure their atmospheric properties through the technique of transmission spectroscopy: the variation of the transit depth as a function of wavelength due to starlight interacting with the atmosphere of the exoplanet. Motivated by the need of optical transmission spectra of exoplanets, we recently launched the Arizona-CfA-Católica Exoplanet Spectroscopy Survey (ACCESS), which aims at studying the atmospheres of ~20 exoplanets ranging from super-Earths to hot-Jupiters in the entire optical atmospheric window using ground-based facilities. In this talk, I will present the survey, the astrostatistical challenges it poses and first results.

Wednesday June 10, 2015
Dr. Nikolay Kacharov
University of Heidelberg


I will talk about our current understanding of globular cluster (GC) formation and what we have yet to learn about them. I will particularly focus on the chemical and dynamical properties of the neglected GC NGC4372, which I studied for the first time with  high-resolution spectroscopic observations.
Its chemical abundances revealed it as a typical representative of the old, metal-poor halo group. More interesting, however, are its structural and kinematic properties as the cluster has an unusually high intrinsic rotation for its metallicity and appears to be rotationally flattened. I will discuss what
rotating GCs tell us about their early evolution.

Tuesday January 27, 2015
Mr. Ben Hendricks
Univ of Heidelberg


Dwarf spheroidal (dSph) galaxies are the smallest, closest and most abundant galaxies in the Universe and therefore excellent laboratories to study star formation (SF) history and chemical evolution on the smallest
scales. However, the complexity within---and variations between---these objects are poorly understood, not least because the vast majority of present-day data is restricted to the most central regions of these systems.
Thus, the scope of this talk is to present the results from our chemodynamical analysis (i.e., combining chemical abundances, stellar
ages, and precise dynamical measurements from high-resolution spectra) of the outer regions of Fornax and to put them in a general context of the chemical evolution in dSphs and their key-regulating factors. On this basis, possible (and impossible) evolutionary scenarios for Fornax are discussed and compared with model predictions.  Furthermore, Fornax is one amongst very few dSphs with an own globular cluster population. In the last part of my talk I use the results from our analysis and discuss
ongoing projects designed to address the impact of globular clusters on the evolution of this galaxy, and vice versa.

Thursday April 24, 2014
Mr. Antonio Manescau
ESO Garching


MUSE (Multi Unit Spectroscopic Explorer) is a 2nd generation Integral Field facility for the VLT. With a field of view of 1x1 arcmin, fine sampling, intermediate spectral resolution and large spectral coverage in the visible, it uses a complex image slicer, twenty-four parallel spectrographs and a large detector area. In addition, MUSE is conceived to work assisted by the Adaptive Optics Facility (AOF), which will enhance notably its performance. MUSE is the result of ten years of design and development by the MUSE consortium — headed by the Centre de Recherche Astrophysique de Lyon, France and the partner institutes Leibniz-Institut für Astrophysik Potsdam (AIP, Germany),  Institut für Astrophysik Göttingen (IAG, Germany),  Institute for Astronomy ETH Zurich (Switzerland), L'Institut de Recherche en Astrophysique et Planétologie (IRAP, France), Nederlandse Onderzoekschool voor de Astronomie (NOVA, the Netherlands) and ESO.
MUSE has been successfully installed on ESO’s Very Large Telescope (VLT). In this talk it will be presented the instrument, its design and challenges, the integration (both in Europe and Paranal), the first light and first commissioning results.

Tuesday March 5, 2013
Drs. Carlos Allende, Ismael Perez Fournon


This has been an exciting year for the SDSS-III collaboration. BOSS has made spectacular progress and it is running 6 months ahead of schedule. APOGEE has secured ~ 300,000 spectra for 50,000 stars, mostly red giants and nearly half of its total sample. The APOGEE Stellar Parameter and Chemical Abundance Pipeline is providing reliable atmospheric parameters, including metallicities. Data Release 10 (DR10) will take place next summer, but DR10 BOSS data are already available to the collaboration, and DR10 APOGEE data products will be internally released in the next few weeks. SDSS activity is growing at the IAC. We will report on SDSS-III news and SDSS-IV prospects, including an overview of the SDSS-IV programs APOGEE-2, eBOSS (+TDSS+SPIDERS), and MaNGA.

Thursday February 7, 2013
Dr. Simon Albrecht
MIT Kavli Institute for Astrophysics and Space Research


Spectroscopic observations of stars do not only provide us with valuable information about the stars themselves, but over the last years such observations have lead to numerous exoplanet discoveries and new insights into planet formation. One important clue emerged at the dawn of the field: the existence of hot Jupiters, gas giants with orbital distances much smaller than an astronomical unit. We and other groups found some of these planets orbiting their stars on highly inclined or even retrograde orbits. I show how the orientation of the stellar axis in relation to the orbital plane (obliquity) reveals the mechanism by which these planets move inwards. Similar measurements in multiple transiting planet systems, with smaller planets will further enhance our understanding of the formation and evolution of planetary systems. In order to take those measurements we need to improve the way we analyze spectra. I present recent results obtained with such a new technique. These include multiple planet systems and results from my "BANANA" survey of close binaries, some of which, such as DI Herculis, also show strong misalignment. The same technique will allow for a reduction of stellar noise in radial velocity surveys, improving our ability to search for smaller, more Earth like planets around bright nearby stars.

Thursday September 20, 2012
Dr. Gavin Dalton
University of Oxford


I will describe the major scientific motivation and outline design concept for a new 2 degree field, 1000 fibre multi-object spectroscopy facility for the WHT. WEAVE is expected to be completed by early 2017 and will be capable of addressing a wide range of Galactic and extra-Galactic goals, covering the redial velocity follow-up to the full depth of the Gaia astrometric catalogue, stellar abundances and chemical labelling in the Galactic halo, galaxy evolution from integral field studies and from the identification of the LOFAR source population, and Cosmology. The instrument is complex, but not necessarily challenging, and will provide a major resource for the whole ING community for the next decade.

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