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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Slides: PPT | PDF | HTML
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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.
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Slides: PDF | PPT | HTML
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Presentation: DVD (please contact Javier Méndez) |
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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. |
Slides:
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Presentation: DVD (please contact Javier Méndez) |
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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
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Presentation: DVD (please contact Javier Méndez) |
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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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