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Certain types of large amplitude AGB variable are proving to be powerful distance indicators that will rival Cepheids in the James Webb Space Telescope era of high precision infrared photometry. These are predominantly found in old populations and have low mass progenitors. At the other end of the AGB mass-scale, large amplitude variables, particularly those undergoing hot bottom burning, are the most luminous representatives of their population. These stars are < 1 Gyr old, are often losing mass copiously and are vital to our understanding of the integrated light of distant galaxies as well as to chemical enrichment. However, the evolution of such very luminous AGB variables is rapid and remains poorly understood. Here I discuss recent infrared observations of both low- and intermediate-mass Mira variables in the Local Group and beyond.
The changing total luminosity of SN 1987A between 2 and 1200 days after core collapse is illustrated and discussed. From about four weeks after outburst the supernova light curve was dominated by the release of radioactive decay energy; the major contributor being 0.078M⊙ of 56Co. Recently an additional contribution probably from the decay of 57Co and 44Ti appears to be manifesting itself in the light curve. A gradually increasing fraction of the radioactive decay energy has probably been emitted at X- and γ-ray wavelengths; the fluxes are low and no recent measurements have been published. Most of the remaining radioactive decay energy appears to be emitted in the IR and is very difficult to measure. Other factors influencing the interpretation of the recent light curve are the uncertain contribution from long-lived radioactive isotopes and light-echoes. It is therefore premature to make any definitive statements on the contribution from the neutron star, although it is probably less than a few times 1037 erg s−1.
Variable stars have a unique part to play in Galactic astronomy. Among the most important of these variables are the Cepheids (types I and II), the RR Lyraes and the Miras (O- and C-rich). The current status of the basic calibration of these stars in their roles as distance, structure and population indicators is outlined and some examples of recent applications of these stars to Galactic and extragalactic problems are reviewed. The expected impact of Gaia on this type of work is discussed and the need for complementary ground based observations, particularly large scale near-infrared photometry, is stressed.
Large-amplitude asymptotic giant branch variables potentially rival Cepheid variables as fundamental calibrators of the distance scale, particularly if observations are made in the infrared, or where there is substantial interstellar obscuration. They are particularly useful for probing somewhat older populations, such as those found in dwarf spheroidal galaxies, elliptical galaxies or in the haloes of spirals. Calibration data from the Galaxy and new observations of various Local Group galaxies are described and the outlook for the future, with a calibration from Gaia and observations from the next generation of infrared telescopes, is discussed.
In the article by Crabtree et al., published in Transactions IAU, Volume XXVIIIA there was an error in the list of authors. Pedro Russo was not included in the list of authors on the organizing committee. The editors apologise to Pedro Russo for this error. The correct authorship is published below:
PRESIDENT: Dennis R. Crabtree
VICE-PRESIDENT: Lars Lindberg Christensen
PAST PRESIDENT: Ian Robson
ORGANIZING COMMITTEE: Oscar Alvarez Pomare, Augusto Damineli Neto, Richard T. Fienberg, Anne Green, Ajit K. Kembhavi, Pedro Russo, Kazuhiro Sekiguchi, Patricia Ann Whitelock, Jin Zhu
Commission 55 was approved at the IAU General Assembly in Prague following the great success of the Communicating Astronomy Working Group, which had been set up in 2003. It resides within Division XII and the mission statement of the Working Group has been incorporated into the Commission:
• To encourage and enable a much larger fraction of the astronomical community to take an active role in explaining what we do (and why) to our fellow citizens.
• To act as an international, impartial coordinating entity that furthers the recognition of outreach and public communication on all levels in astronomy.
• To encourage international collaborations on outreach and public communication.
• To endorse standards, best practices and requirements for public communication.
Multi-epoch JHKS photometry is used to identify large amplitude variables and to study the AGB population of NGC 6822. 50 Mira variables, ranging in period from 128 to 998 days, have been identified. The majority of these are around 1 to 4 Gyr old, but a significantly younger component is also identified.
Since its formation at the XXVI General Assembly in Prague in 2006, amazing progress has been made by Commission 55, all due to the work of the key activists and enthusiasts. The web-page for the Commission contains a wealth of information and is one of the key foundations and tools for the Commission. The web address is http://www.communicatingastronomy.org
Division VII provides a forum for astronomers studying the Milky Way Galaxy and its constituents. Several meetings directly relevant to his subject were held at the General Assembly in Rio: IAU Symp. 262 Stellar Populations, IAU Symp. 265 Chemical Abundances in the Universe, IAU Symp. 266 Star Clusters, Joint Discussion 5 Modeling the Milky Way in the Era of Gaia, and Special Session 5 The Galactic Plane. Division VII therefore did not organize a separate science session at Rio, but business meetings were held for both the Division and for Commissions 33 and 37.
Commission 33 held its business session in the afternoon of Friday 7 August 2009. The president briefly described developments during the previous months. A short discussion followed about the activities of the Commission and whether it should play a more active role in view of the many on-going surveys relevant to the subject of the Galaxy.
Astronomy was one of the sciences earmarked for major support by South Africa's first democratically elected government in 1994. This was a very remarkable decision for a country with serious challenges in poverty, health and unemployment, but shows something of the long term vision of the new government. In this paper I give one astronomer's perception of the reasons behind the decision and some of its consequences.
Commission 33 provides a forum for astronomers studying the structure and dynamics of the Milky Way Galaxy, a unique laboratory for exploring the stellar and gaseous components of galaxies and the processes by which they form and evolve.
The Supernova Working Group was re-established at the IAU XXV General Assembly in Sydney, 21 July 2003, sponsored by Commissions 28 (Galaxies) and 47 (Cosmology). Here we report on some of its activities since 2005.
Division VII gathers astronomers studying the diffuse matter in space between stars, ranging from primordial intergalactic clouds, via dust and neutral and ionized gas in galaxies, to the densest molecular clouds and the processes by which stars are formed.
Division VII provides a forum for astronomers studying our home galaxy, the Milky Way, which offers a unique laboratory for exploring the detailed structure of the stellar and gaseous components of galaxies and the process by which they form and evolve.
HST multi-epoch images and VLT integral-field, high resolution spectroscopy allowed us a robust determination of the 3-D geometry and orientation of the nebula surrounding He 2-147, and to measure its apparent expansion in the plane of the sky. Applying the expansion parallax method results in a distance which is significantly shorter that the one obtained via the period-luminosity (P-L) relationship for the Mira component. We show how allowing for shock excitation of the nebula, as suggested by the extremely broad nebular line profiles, enables both distance derivations to be reconciled.
The commission supported the following IAU symposia and colloquia during the period 2002 to 2005: Dark Matter in Galaxies (IAUS220), Gravitational Lensing Impact on Cosmology (IAUS225); Transit of Venus: New Views of the Solar System and Galaxy (IAUC196); Populations of High-Energy Sources in Galaxies (IAUS230); Scientific Requirements for Extremely Large Telescopes (IAUS232).