[MODEST] IAU Symposium 289: Advancing the Physics of Cosmic Distances [1st announcement]

[Richard de Grijs]

               F I R S T   A N N O U N C E M E N T

          International Astronomical Union Symposium 289

           "Advancing the Physics of Cosmic Distances"
        http://www.mporzio.astro.it/IAUS289/www/Home.html
                       iaus289 at gmail.com

IAU General Assembly, National Convention Centre, Beijing (China)

                        27-31 August 2012

(For practical information, scroll to the bottom of this announcement.)

** SOUNDBITE: **

Knowing the distance of an astrophysical object is key to
understanding it. However, at present, comparisons of theory and
observations are hampered by precision (or lack thereof) in distance
measurements or estimates. Putting the many recent results and new
developments in relevant subareas into the broader context of the
physics driving cosmic distance determination is the next logical
step, which will benefit from the combined efforts of theorists,
observers and modellers working on a large variety of spatial scales,
and spanning a wide range of expertise. This Symposium will focus on
the physics underlying methods of distance determinations across the
Universe, exploring on the way the various methods employed to define
the milestones along the road. We aim to provide a snapshot of the
field of distance measurement, offering not only up-to-date results
and a cutting-edge account of recent progress, but also full
discussion of the pitfalls encountered and the uncertainties that
remain. We aim to provide a roadmap for future efforts in this field,
both theoretically and observationally.


** SCIENTIFIC ORGANISING COMMITTEE: **

Richard de Grijs    (KIAA, Peking University, China) - co-chair
Giuseppe Bono       (Università Roma Tor Vergata, Italy) - co-chair

Susan Cartwright    (University of Sheffield, UK)
Robin Ciardullo     (Pennsylvania State University, USA)
Andrei Dambis       (Sternberg Astronomical Institute, Russia)
Michael Feast       (University of Cape Town, South Africa)
Wendy Freedman      (Carnegie Observatories, USA)
Wolfgang Gieren     (Universidad de Concepción, Chile)
Martin Groenewegen  (Royal Observatory of Belgium, Belgium)
Jeremy Mould        (Swinburne University of Technology, Australia)
Carme Jordi         (Universitat de Barcelona, Spain)
Mark Reid           (Harvard-Smithsonian Center for Astrophysics, USA)
Myung-Hyun Rhee     (Yonsei University, Republic of Korea)
Don VandenBerg      (University of Victoria, Canada)
Rogier Windhorst    (Arizona State University, USA)
Ye Xu               (Purple Mountain Observatory, China)


** SCIENTIFIC RATIONALE: **

Knowing the distance of an astrophysical object is key to
understanding it: without an accurate distance we do not know how
bright it is, how large it is, or even (for long distances) when it
existed. But astronomical distance measurement is a challenging
task. Distances to stars were first measured in 1838 by Bessel, Struve
and Henderson, and accurate distances to other galaxies -- even the
nearest -- date only from the 1950s. This is not really surprising,
since the only information we have about any object beyond our Solar
System is its position (perhaps as a function of time) and its
brightness (as a function of wavelength and time). Yet, from this
unpromising starting point, modern astronomers have developed methods
of measuring distances which can take us from the nearest star to the
most distant galaxy, using techniques that vary from the mundane (the
astronomical equivalent of the surveyor's theodolite) to the exotic
(the bending of light in general relativity, wiggles in the spectrum
of the cosmic microwave background). Nevertheless, the most accurate
optical and near-infrared methods of distance determination, from the
solar neighbourhood to the highest redshifts, in use today rely
heavily on having access to accurate spectroscopy, supplemented by
astrometric measurements in the Milky Way (and slightly beyond).

In 1997, the Hipparcos space mission provided (for the first time) a
significant number of absolute trigonometric parallaxes at
milliarcsec-level precision across the whole sky, which had a major
impact on all fields of astrophysics. In addition, during the past ten
years, the use of ground-based 8-10mclass optical and near-infrared
telescopes (Keck, VLT, Gemini, Subaru) and space observatories (HST,
Spitzer, Chandra, XMM-Newton) have provided an unprecedented wealth of
accurate photometric and spectroscopic data for stars and galaxies in
the local Universe. Radio observations, particularly with the VLBA and
the Japanese VERA arrays, have achieved 10 micro-arsecond astrometric
accuracy. Moreover, stellar models and numerical simulations are now
providing accurate predictions of a broad range of physical phenomena,
which can now in principle be tested using accurate spectroscopic and
astrometric observations (including measurements of, e.g., line ratios
and shapes, spectral slopes, radial velocities and velocity
dispersions). However, at present, comparisons of theory and
observations are mainly hampered by precision (or lack thereof) in
distance measurements/estimates.

While a number of past IAU Symposia have addressed individual aspects
of the methods and physics underlying the fundamentals of distance
determination, at the present time there is a need for a new,
interdisciplinary Symposium encompassing the broad range of techniques
and theories. Rather than focusing on historical perspectives, we will
truly highlight the tremendous amount of recent and continuing
research into a myriad of exciting and promising aspects of accurately
pinning down the cosmic distance scale. Putting the many recent
results and new developments in the relevant subareas into the broader
context of the physics driving cosmic distance determination is the
next logical step, which will benefit from the combined efforts of
theorists, observers and modellers working on a large variety of
spatial scales, and spanning a wide range of expertise.

This is a very exciting time. VLBI sensitivity is being expanded
allowing, for example, direct measurement of distances throughout the
Milky Way and even to Local Group galaxies. The field will benefit
from expert input to move forward into the era of Gaia,
optical-interferometer and ELT-driven science, which (for example)
will allow us to determine Coma-cluster distances without having to
rely on secondary distance indicators, thus finally making the leap to
accurate distance measurements well beyond the Local Group of
galaxies. With the launch of Gaia imminent at the time of the IAU GA
in Beijing, this is a really opportune time to be looking forward to
the first Gaia catalogues, and understand how the science areas
touched upon in this Symposium will be fundamentally changed by the
Gaia results, what the big open questions are that Gaia can address in
the Symposium's context, and what the future of complementary
techniques and observational approaches will be once the Gaia
catalogues become available.

In this Symposium, we will bring together experts on various aspects
of distance determinations and (most importantly) the underlying
physics enabling this (without being restrictive in areas where
statistical and observational approaches are more relevant), from the
solar neighbourhood to the edge of the Universe, exploring on the way
the various methods employed to define the milestones along the
road. We will emphasise, where possible, the physical bases of the
methods and recent advances made to further our physical insights. We
aim to provide a snapshot of the field of distance measurement,
offering not only up-to-date results and a cutting-edge account of
recent progress, but also full discussion of the pitfalls encountered
and the uncertainties that remain. We aim to provide a roadmap for
future efforts in this field, both theoretically and observationally,
and in particular will consider the key question as to whether the
field is best served by having access to the nextgeneration of
extremely large telescopes and the Square Kilometer Array (as well as
the James Webb Space Telescope) and/or if significant progress can
still be made with dedicated 2-4m-class optical telescopes as well as
upgraded radio interferometers.

Although our focus is techniques of distance determination, this is
intimately linked to many other aspects of astrophysics and
cosmology. On our journey from the solar neighbourhood to the edge of
the Universe, we shall encounter stars of all types, alone, in pairs
and in clusters, their life cycles, and their explosive ends: binary
stars, in particular, play an important role in this context, e.g. in
pinning down accurate distances to the Pleiades open cluster and Local
Group galaxies, as well as in future ground- and space-based surveys
(including Gaia, RAVE, and others); the stellar content, dynamics, and
evolution of galaxies and groups of galaxies; the gravitational
bending of starlight; and the expansion, geometry and history of the
Universe. As a result, the Symposium will offer not only a
comprehensive study of distance measurement, but a tour of many recent
and exciting advances in astrophysics.


** REGISTRATION/TRAVEL GRANTS: **

Registration for this Symposium must be done via the IAU General
Assembly's registration process: 
- http://www.astronomy2012.org/dct/page/65611

Note that the early registration deadline is 29 February 2012.

All participants, INCLUDING INVITED AND REVIEW SPEAKERS, must register
via the IAU GA website.

If you are not an IAU member, the IAU's Paris Office will issue an
official invitation once your status as professional astronomer has
been verified. To aid this process, please register as usual and also
send an email to the Symposium's organisers (iaus289 at gmail.com),
including:
- your name and gender (important!)
- your full institute address
- your professional status (student, postdoc, faculty, etc.)

Students also need to ask their adviser to send an endorsement letter
directly to the IAU's secretariat; see
http://www.astronomy2012.org/dct/page/65611 (note 1).

If you want to qualify for partial TRAVEL SUPPORT, the deadline for
travel grant applications is also 29 February. See for more details:
http://www.iau.org/grants_prizes/iau_grants/ga_events/ -- we cannot
provide firm guarantees of travel support before 8 May 2012, and there
is no need to follow up any enquires prior to that date (we won't have
the answers).


We hope to see many of you at IAU Symposium 289 in Beijing this summer!