[AAA] symposio IAU 307 - New windows on massive stars ...

[Lydia Cidale]

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Muchas gracias
saludos
Lydia

FIRST ANNOUNCEMENT

IAU symposium 307

"NEW WINDOWS ON MASSIVE STARS:
Asteroseismology, interferometry, and spectropolarimetry"

Geneva (Switzerland)
June 23-27, 2014
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* CONTACT:

email: iau307 en unige.ch
webpage: http://obswww.unige.ch/Conferences/IAU307/


* IMPORTANT DATES:

Deadline for grant request:                 January 31, 2014
Deadline for abstract submission:     April 30, 2014
Deadline for early fees (250 CHF):   May 15, 2014
Conference:                                           June 23-27, 2014


* SCIENTIFIC RATIONALE:

The important outputs of mass, momentum and energy of massive stars strongly
modify their environment and make them key agents in the evolution of
galaxies during the whole of cosmic history. Their high luminosities make
them objects detectable at far distances in the Universe. Massive stars
are thus important probes for studying star formation at high redshifts. As
the progenitors of core collapse supernovae, of the long soft Gamma Ray
Bursts, and of neutron stars and black holes, they are connected with the
most intriguing objects in the Universe.

Their physics is, however, not yet very well known and such basic
understanding as the origin of the various massive star populations (Be-type
stars, red and blue supergiants, Luminous Blue Variables, Wolf- Rayet stars)
are still matters of debate, as well as the nature of the progenitors of the
various types of core-collapse supernovae (type IIP, IIL, IIb, IIn, Ibc).

Among the great challenges faced nowadays in our understanding of massive
star evolution, we can cite the following two points :
• Hydrodynamical processes: turbulent flow, rotation, magnetic fields, as
well as mass loss, are all basically fluid dynamics of plasmas. These
processes, by governing the quantity of fuel available for a given nuclear
burning stage, by modifying the chemical structure of the stars, and by
allowing the total mass to strongly decline with time have a dramatic impact
on the evolution of massive stars. This also has  strong consequences on the
chemical evolution of galaxies and on the evolution of their spectral energy
distribution.
• Role of multiplicity in massive star evolution : in addition to the
complex physics involved in single stars, multiplicity adds new types of
interactions through tidal forces, mass transfer and/or stellar mergers,
opening the path to a variety of different evolutionary pathways populating
various parts of the HR diagram and leading to specific final structures and
thus particular supernova events.

Nowadays, asteroseismology, interferometry and spectropolarimetry allow a
view into what could have been thought once as unreachable characteristics
of stars in general and of massive stars in particular, and thus can provide
new clues on how massive stars are evolving:
• Asteroseismology (MOST, CoRoT, Kepler, BRITE) allows to probe what happens
into the interior of stars, to identify the zones where steep gradients of
chemical composition and of angular velocity occur. This provides essential
clues on transport processes inside stars. These transport processes,
together with the change of composition due to nuclear reactions and mass
loss by stellar winds and/or through mass transfer in close binaries drive
the evolution of stars.
• Interferometry (e.g. VLTI, CHARA) explores the shape of stars, the
structure and the kinematics of their circumstellar environments. This
allows us to probe the deformation of stars resulting from fast rotation
and/or tidal forces, to explore the physics of disk formation around
early-type stars, to obtain diagnostics of possible anisotropies in the
stellar winds and probably in the future to determine if
latitudinal differential rotation occurs at the surface of massive stars.
• Spectropolarimetry (Narval, Espadons, HARPSpol) gives information on the
amplitudes and topologies of surface magnetic fields. Magnetic fields
represent one of the great issues in massive star physics. Fields impact the
way angular momentum is distributed in the interior and it may also couple
the wind with the surface of the star. These two characteristics probably
play a key role in the angular momentum content of the core at the time of
the core-collapse event and thus have an important impact on the way stars
explode and on the physical properties of the stellar remnants (neutron
stars and black holes).

All these three techniques have already obtained fascinating results on
massive stars and the time is ripe for organising an international
conference focusing on the achievements reached so far. The main aims of the
conference will be to:
• allow astronomers interested in massive stars to understand the basics of
these three techniques, to what extent the results obtained depend on the
theoretical models used for the interpretation of the observed features, to
understand the potential of these techniques as well as their present
limitations and future developments;
• explore the potential benefits and synergies of these techniques used
together and also with more classical approaches such as photometry and
spectroscopy to address topical questions in massive star evolution;
• allow observers to learn about the most recent challenges in massive star
modeling.


* TOPICS:

The conference will cover the following topics in 6 sessions:

Session 1: CHALLENGES IN MASSIVE STAR EVOLUTION

• Hydrodynamic processes in massive stars and consequences for understanding
the main observed characteristics of massive stars
• Massive star populations in galaxies
• Starbursts in distant galaxies
• Chemical evolution of galaxies

Session 2: ASTEROSEISMOLOGY

• How are the interesting astrophysical quantities extracted from the data ?
To what extent do these values depend on models ?
• What can be said about the size of the convective core during main
sequence evolution ?
• What can be said about the way massive stars rotate internally ? (solid
body or not ?)

Session 3: INTERFEROMETRY

• How are the interesting astrophysical quantities extracted from the data ?
To what extent do these values depend on models ?
• The shape of stars and testing of the von Zeipel theorem
• Stars with disks.
• Stars with polar winds
• Surfaces of massive stars (differential rotation ?)
• Sizes of the convective cells at the surface of red supergiants ?

Session 4: SPECTROPOLARIMETRY

• How are the interesting astrophysical quantities extracted from the data ?
To what extent do these values depend on models ?
• Results of large surveys
• Fossil or dynamo fields ?
• Is there any correlation of the strength of the surface magnetic field
with other observed quantities as surface abundances and rotation ?

Session 5: SYNERGY BETWEEN DIFFERENT TECHNIQUES

• Can we see how a star having a strong surface magnetic field rotates
internally ?
• Have the slow rotators with strong surface nitrogen enhancement a
detectable surface magnetic field ?

Session 6: TOWARDS A SYNTHETIC VIEW OF MASSIVE STAR EVOLUTION

• What are the perspectives for studying stars in stellar clusters with
these techniques ?
• What can be expected from future observational facilities ?
• A summary of the conference will be presented by invited speakers.


* LIST OF CONFIRMED INVITED SPEAKERS (provisional):

C. Aerts
D. Arnett
A. Chieffi
J. Grunhut
J. Landstreet
N. Langer
A. Maeder
C. Meakin
A. Meilland
A. Miglio
A. Noels
N. Przybilla
J. Puls
P. Stee
A. Ud Doula
G. van Belle
G. Wade


* SCIENTIFIC ORGANISING COMMITTEE:

Georges Meynet (Switzerland) -- Chair
Philippe Stee (France) -- Co-chair

David Arnett (USA)
Lydia Cidale (Argentina)
Raphael Hirschi (UK)
Emily Levesque (USA)
Marco Limongi (Italy)
André Maeder (Switzerland)
Philip Massey (USA)
Coralie Neiner (France)
Arlette Noels (Belgium)
Stanley Owocki (USA)
Thomas Rivinius (Chile)
Hideyuki Saio (Japan)
Rich Townsend (USA)
Gregg Wade (Canada)


* LOCAL ORGANISING COMMITTEE:

Georges Meynet -- Chair

Patrick Eggenberger
Sylvia Ekström
Anahí Granada
José Groh
Lionel Haemmerlé
Giovanni Privitera
Gilles Simond
Chantal Taçoy