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Seminars in 2007

Date: 6 November (Tuesday) Time: 16:00 Place: 6th floor meeting room, Mayantigo building
Title: Observational Evidence for Radiative Grain Alignment
Speaker (Affiliation): B-G Andersson (SOFIA/USRA, USA)
Abstract: It was realized soon after interstellar polarization was first detected in 1949, that the effect was caused by an interaction between the dust and magnetic field in the interstellar medium. Over the following decades significant theoretical progress has been made in understanding the alignment mechanism, with the current consensus favoring alignment by direct radiative torques. However, little direct observational evidence has been available to constrain the details of the grain alignment. We have recently used multi-band optical, and NIR, polarimetry towards six nearby clouds, supported by optical, NIR and FIR photometry, to show that the grain alignment is indeed driven by radiative processes. Our data also show a strong impact of the local star formation on the polarization, including possible alignment damping due to the X-ray field from embedded YSOs. A quantitative understanding of interstellar grain alignment promises to, allow new probes of the grain micro physics and, put the potentially powerful diagnostics of the magnetic field available through optical/NIR and FIR polarimetry on a secure footing.
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Date: 23 October (Tuesday) Time: 04:00pm Place: 6th floor meeting room, Mayantigo building
Title: ULTRASPEC: High-speed spectroscopy with zero readout noise
Speaker (Affiliation): Vik Dhillon (Sheffield University, UK)
Abstract: ULTRASPEC is a high-speed, spectroscopic camera based on electron-multiplying CCDs (EMCCDs) and the data acquisition system of ULTRACAM. The project is a collaboration between the Universities of Sheffield, Warwick and the UK Astronomy Technology Centre, with funding provided by OPTICON. ULTRASPEC was tested for the first time on-sky in December 2006 on the EFOSC2 spectrograph of the ESO 3.6-m telescope at La Silla. In this talk, I will present details of ULTRASPEC's design and performance, and our plans for future work.
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Date: 16 October (Tuesday) Time: 12:00am Place: 6th floor meeting room, Mayantigo building
Title: Properties of the Broad Line Region of quasars at z~0.3
Speaker (Affiliation): Roberto Decarli (Istituto Nazionale di Fisica Nucleare, Italy)
Abstract: I'll present an analysis of the broad line emission of Hbeta and CIV in a sample of =0.3 quasars, the host galaxies of which were resolved. Comparing the virial estimates of the massive black hole masses, based on the line width, with the ones obtained from the host-galaxy luminosities, we constrain the dynamics of the emitting clouds. The line shape is also taken into account. I'll sketch a tentative model of the gas dynamics in the broad line region, and discuss its outcomes in the general Type-1 AGN phenomenology.
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Date: 16 August (Wednesday) Time: 12:00am Place: 6th floor meeting room, Mayantigo building
Title: Rotation and massive star evolution
Speaker (Affiliation): Ian Hunter (ING and Queen's University Belfast, UK)
Abstract: Rotation is now considered a fundamental property in theoretical models of the evolution of massive stars; in particular the prediction that core processed material is rotational mixed to the surface via the process of rotational mixing. However, such theories have never been observationally tested, for example, one would expect the fastest rotators to be the most mixed but analyses of such fast rotators have never before been carried out. Here the analysis of over 100 LMC B-type massive stars are presented and surface nitrogen enrichments are used as an indicator of the efficiency of the mixing mechanism. Models including rotation have been generated to best fit the observed data and the discrepancies between these theoretical models and the observations are highlighted. In particular several fast rotators with no evidence of rotational mixing are observed despite being close to the end of their hydrogen burning lifetimes. Additionally a significant population of slow rotators with lots of chemical enrichment is seen. Both these populations violate the current theories of rotational mixing and challenge our understanding of massive evolution.
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Date: 16 August (Wednesday) Time: 12:00am Place: 6th floor meeting room, Mayantigo building
Title: Transiting extrasolar planets
Speaker (Affiliation): Marie Hrudková (ING and Charles University, Czech Rep.)
Abstract: Transiting extrasolar planets are very important class of exoplanets. Using an accurate light-curve one can get a mass-radius relationship which is useful to probe a planet's internal structure and helps us to better understand planetary formation processes and the system evolution. Measuring transit times could reveal other bodies in the system, like other planets, moons or trojans. For this reason I analyzed data of TrES-1 taken with AG3 CCD on the William Herschell Telescope and with a timing precision ~10 s we can exclude for example an Earth-mass planet in an eccentric orbit (e=0.4) of a period up to 15 days. I developed the code for modelling system parameters using Markov Chain Monte Carlo simulations and presented first results of these modelling techniques.
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Date: 1 June (Friday) Time: 10:30am Place: Meeting room, CALP (broadcasted from IAC)
Title: Cosmic Microwave Background Radiation, Clusters of Galaxies and Cosmology
Speaker (Affiliation): Prof. Rashid A. Sunyaev (MPIA)
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Date: 31 May (Thursday) Time: 12:30am Place: Meeting room, CALP (broadcasted from IAC)
Title: Elípticas: modelos de evolución y cinemática por mergers
Speaker (Affiliation): Dr. César González García (UCM)
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Date: 29 May (Tuesday) Time: 10:30am Place: Meeting room, CALP (broadcasted from IAC)
Title: The sky in hard X-Rays
Speaker (Affiliation): Prof. Rashid A. Sunyaev (MPIA)
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Date: 17 May (Thursday) Time: 12:30am Place: Meeting room, CALP (broadcasted from IAC)
Title: FRIDA. El primer instrumento de óptica adaptativa para GTC: ciencia y desafíos técnicos
Speaker (Affiliation): Javier Fuentes (IAC)
Abstract: FRIDA (inFRared Imager and Disector for the Adaptive optics system of GTC) es un instrumento de infrarrojo cercano, con capacidad para imagen y espectroscopía de campo integral con resoluciones espaciales al limite de difracción de GTC, y espectrales entre 1200 y 30.000. FRIDA se instalará en uno de los focos Nasmyth del telescopio, acoplada al sistema de óptica adaptativa de GTC.

FRIDA se está desarrollando como una colaboración entre los grupos instrumentales de España (IAC), México (IA-UNAM) y Floridad (UF). En este seminario se presentarán tanto los desafíos científicos que se pueden abordar con este instrumento como el estado actual de su desarrollo técnico y los problemas específicos que su ingeniería plantea.

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Date: 10 May (Thursday) Time: 12:30am Place: Meeting room, CALP (broadcasted from IAC)
Title: The long bar in the Milky Way
Speaker (Affiliation): Antonio Cabrera Lavers (GTC-CALP)
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Date: 8 May (Tuesday) Time: 12:30am Place: Meeting room, CALP (broadcasted from IAC)
Title: Astrophotography: Image Processing
Speaker (Affiliation): Nik Szymanek (CCDLAND)
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Date: 18 April (Wednesday) Time: 03:30pm Place: Meeting room, CALP
Title: Modified Newtonian Dynamics (MOND), an introductory review
Speaker (Affiliation): Riccardo Scarpa (GTC)
Abstract: I will review the basics of MOND, to highligh the many successes this idea achieved in describing the properties of galaxies and other cosmic structures without the needs for dark matter. Among other things, particular relevance will be given to the quest for MOND effects in globular clusters.
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Date: 8 March (Thursday) Time: 12:00am Place: 6th floor meeting room, Mayantigo building
Title: Constraints on supernova progenitors from local stellar populations
Speaker (Affiliation): Joseph Paul Anderson (Astrophysics Research Institute, Liverpool John Moores University)
Abstract: We are attempting to constrain SN progenitors, through correlations of the positions of historical SNe with different stellar populations in external galaxies. Our initial investigation has studied the association of SN progenitors of all types, with recent star formation, as traced by H-alpha emission (James & Anderson 2006). We have found the unexpected result, that there seems to be an excess of ~33% of the SNII progenitor population that do not show any association with recent star formation. The explanation for this discrepant population is still unclear, and we are currently working on several hypotheses. The SNIb/c population however, does seem to trace the H-alpha emission accurately, implying that these SNe do indeed originate from high mass stars. SNIa show a small degree of association with star forming regions, but this association could be down to chance alignments and further investigation is needed. With this last point in mind we are now turning our attention to a more extensive, multi-wavelength study of the local stellar populations of SNIa progenitors. We are obtaining near-IR and broad-band optical imaging of a large number of SNIa host galaxies. We plan to use these, in conjunction with the stellar population synthesis models of Pietrinferni et al. (2004), to map a wide range of stellar ages and metallicities, in order to tie down the SNIa progenitor population further.
Slides: PDF | PPT | HTML
Presentation: DVD (please contact Javier Méndez)
 

Date: 1 March (Thursday) Time: 12:00am Place: 6th floor meeting room, Mayantigo building
Title: Spins and Origins of Near-Earth Objects
Speaker (Affiliation): Alan Fitzsimmons (QUB)
Abstract: The past decade has seen a consensus reached on the primary mechanisms by which asteroids in the main belt evolve into Near-Earth Objects (NEOs). In turn this predicts physical characteristics and effects that should be observable with current facilities. This seminar will review our current understanding in this area, and I will present recent findings made with (among others) the INT and LT.
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Presentation: DVD (please contact Javier Méndez)
 

Date: 5 February (Monday) Time: 11:00am Place: 6th floor meeting room, Mayantigo building
Title: Astronet: A Science Vision for European Astronomy
Speaker (Affiliation): Danny Lennon (ING)
Abstract: 'A Science Vision for European Astronomy in the Next 20 Years' was the title of a symposium held on January 23-25, 2007, Poitiers, France. The objective of this symposium was to discuss scientific problems and priorities relevant to the future of the European astronomical community. In the coming months this science vision will be developed into a facilities road-map as input into national funding agencies with the idea of improving co-ordination in the funding of astronomy projects. In this talk I recall some highlights of this meeting and discuss some of the potential implications of the process.
Slides: http://www.eso.org/gen-fac/meetings/SciChall07/agenda.html
Presentation: DVD (please contact Javier Méndez)
 

Date: 16 January (Tuesday) Time: 15:00 Place: 6th floor meeting room, Mayantigo building
Title: New tip-tilt system for GLAS
Speaker (Affiliation): Jure Skvarc (ING)
Abstract: The laser-based adaptive optics system still needs to use a natural guide star for tip-tilt corrections. A decision was made at the ING to replace the existing NAOMI tip-tilt control with a new one, using a personal computer for control and a L3 camera as a detector. The system has been constructed and extensively tested on-sky in 2006. The talk will present: a) basic information about the system at the level useful for the users, b) results of the tests including guide star centroid distributions, image corrections and SNR as a function of the guide star magnitude, c) overview of expected operational issues in tip-tilt only applications.
Slides: (on Mayantigo intranet) PDF
Presentation: DVD (please contact Javier Méndez)




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Last modified: 18 December 2010