Monday, August 21, 2006

J. Casares: Observational evidence for stellar-mass black holes

This is the opening review talk of Symposium 238 on Black Holes: from stars to galaxies asross the range of masses. This will be the last talk I listen to before I have to make my way to the airport, but Ulrike Heiter, a collegue from Uppsala who works on stellar atmospheres, said that she might write a few things from S239 about Convection that starts this afternoon and will go on for the rest of this week.

Now to the talk by Casares: X-ray binaries are believed to be a stellar-mass black hole oriting a normal star. From the study of the radial velocity shift, one can determine the orbital period of the system, and from additional information on the star and its mass and properties (inclination of the system), the mass of the black hole can be calculated. The first example for this was 30 years ago.

The reason why these systems shine in X-rays is that material streams from the "donor star" towards the BH and forms an accretion disk around it that gets hot enough to do that. Depending on the type of the donor star, the accretion disk may even be optically brigher than the star during an active phase.

The basic argument of course is, that when you find an object with a high mass that orbits closely with a star, but you cannot see it and physics tells you that there is no way to have such an object withstanding its own gravitational pull, it must be a black hole. However, the number of dynamically confirmed BHs is still quite low (~20).

Also the lack of pulses and X-ray bursts indicates that there is no hard surface onto which things can bounce.

So how many are there and what is the mass-spectrum? Extrapolating from the known numbers tells that there should be 1000 dormant X-ray Transients (i.e. binaries) in our galaxy (this fits with binary models), but from stellar evolution, there should be 10^8 BHs in the Milky Way, out of which only the tip of the iceberg can be seen as XRTs.

The 15 reliable mass estimates range from 4-15 solar masses with more objects on the low-mass end. The most massive ones seem to lie above the values predicted from stellar evolution (Fryer & Kalogera 1999), but we are talking small-number-statistics here (2 objects).

G. Tancredi: Activities of the Observatorio Astronomico Los Molinos, Uruguay

What can be done with a small telescope and a CCD-camera? Quite a lot. The speaker lists several projects that they do at their facility, including confirmation of near-earth objects, comet identification and photometry, asteroid photometry and astrometry. The common-day follow-up observations are valuable contributions to the scientific community and also attacking region in the sky that are rarely studied is a productive niche.

O. Alvarez: Planetario Habana: a cultural centre for science and technology

The funding for this planetarium came internationally (maybe from IAU, I did not get that) and they use it to build up a center for the teaching of science and technology in central Habana. It is integrated with the museums of the city and will promote astronomical knowledge to the public, including cosmology. Architecturally, the big sphere inside the building that will hold the planetarium represents the sun and there will be models of the other planets in the same scale.

Opening will be in the end of 2007.

An inportant comment was made, namely to get to ineract with the teachers and provide help for them and a special program that is different from the popular show. Many planetaria seem to have problems to keep a steady audience that is used to visually impressive films and shows.

P. Rosenzweig: Encounters with science at ULA, Vernezula: An Incetive for Learning

This is about a program to establish science on all levels of education in order to counteract the lack of interest in science and the deterioration in the learning of science. They provide well prepared personnel which can aid faculty members who want to improve things and they organise events ("Encounters with Science") for children at the school of science where an extra effort is made to fight the impression that science is hard and that scientists are heartless, boring people.

These events have many stands with experiments (with much voluntary work from students) and are very popular with several thousand participants and intensive media coverage. This initiative from the most western part of Venezuela has spread over many parts of the country and will soon be held for the seventh time.

J. Fierro: Astronomy for Teachers in Mexico

This talk is about basic education and with a wonderful metaphore (ape-mother teaching the use of tools) she points out the basic structure of learning which includes the natural interest of children and practical experiments.

The speaker was adressed by pre-school teachers with 650 questions of the children and there were books written about how to answer them. These books are very helpful for and popular among teachers. Several other books are presented and she throws a copy of each into the audience. :-)

In middle school, where pupils think more about sex than science, the curriculum is less on astronomy and more on social problems and there are books by the speaker where different issues are adressed in a popular but scientific way.

Finally, she stesses the importance of teachers and of finding good ways to teach, because education is the most important way to leave underdevelopment.

H. Levato: Formal Education in Astronomy in Latin America

The speaker starts with an overview over the countries and places, where astronomy can be studied both at undergraduate and at graduate level. The amount of activity and students scales with the size of the country. 90% of the 500 PhD students in astronomy are in Argentina, Brazil, Chile and Mexico.

There is an intermediate group of countries, where there is serious effort in astronomy, but it would take more resources to consolidate their astronomy programs. The largest number of countries however have seriuous deficiencies in that respect. The speaker also found a correlation between the astronomical effort and the reply-time to emails. :-)

Although there are many astronomical facilities in latin america, it is the people who write the papers and it often is manpower which is the limiting factor.

In a comment it was pointed out, that Venezuela probably should belong to the first group, which the speaker already had suggested, but with a question mark.

J. Ishitsuka: A new astronomical facility for Peru: transforming a 32m-antenna into a radio telescope

There are some big antennae around that are not used anymore, because communication has been replaced by other means. Making telescopes out of them requires expertise which not necessarily available. For this project in Peru, they collaborated with japanese astronomers.

The tansformation of this satellite communication antenna shall start radio astronomy in Peru, create radio anstronomers by gathering knowlege and of course promote international collaborations. The antenna is good enough to go up to 2.2 GHz and the site is high up, remote and has good conditions. The location on the globe also makes it interesting for Very Long Baseline Interferometry. They have a working reciever and are well underway.

S. Haque: The Caribbean view from the ground up

Intitially, the drop-down list in the registration form for this meeting did not contain Trinidad (the speaker's home) - this was corrected. With a country of one million inhabitants and two astronomers, they are approached from all sides of society, also religious, for information about calenders and the sky. There is an effort on online-teaching and there are popular events like "star-parties", however classical seminars are widely ignored.

Astronomy is in the primary school curriculum, voluntary student work is very important and at university level they have succeeded in sending students to internatonal winter schools and universities. Research has mainly been theoretical, but now also contains others, like astrobiology.

They have a 46cm telecope, mainly used for monitoring quasar variability.

R. Kochhar: Promoting astronomy in developing countries: a historical perspective

Is astronomy a "western astronomy"? There has been astronomy going on all over the world during mankind's history. The speaker tries to get attention to insensitivities that for example are written in the history section of textbooks. The "cultural perspective" should be taken more into accont.

J. Hearnshaw: A survey of published astronomical outputs of countries 1976-2005

I could not resist to return to the meeting anyway before I fly back to Sweden tonight. I was tempted by the Session about the "Virtual Observatory", but I guess one can find out about that on the web anyway.

Therefore, I am sitting in the Special Session 5 on "Astronomy for the Developing World" right now. I only got the last minutes of J. Heranshaws talk, but the summary contained the following:
- There are 1.39 astronomers per million population over the world.
- There are 9000 members in the IAU.
- The majority of papers is published by IAU members.
- 112 countries have no IAU members, but 3/4 of the world's population live in IAU member-countries.
- The GDP of a country correlates with the number of it's IAU members.
- It also correlates with the number of papers published.
- Since 2001, there has been a rapid increase in multi-national papers and large collaborations.