European Association for Astronomy Education

Source: ESA PR 15-2010

ESA’s Planck mission has delivered its first all-sky image. It not only provides new insight into the way stars and galaxies form but also tells us how the  Universe itself came to life after the Big Bang.
“This is the moment that Planck was conceived for,” says ESA Director of Science and Robotic Exploration, David Southwood. “We’re not giving the answer. We are opening the door to an Eldorado where scientists can seek the nuggets that will lead to deeper understanding of how our Universe came to be and how it works now. The image itself and its remarkable quality is a tribute to the engineers who built and have operated Planck. Now the scientific harvest must
begin.”
From the closest portions of the Milky Way to the furthest reaches of space and time, the new all-sky Planck image is an extraordinary treasure chest of new data for astronomers.
The main disc of our Galaxy runs across the centre of the image. Immediately striking are the streamers of cold dust reaching above and below the Milky Way.
This galactic web is where new stars are being formed, and Planck has found many locations where individual stars are edging toward birth or just beginning their cycle of development.
Less spectacular but perhaps more intriguing is the mottled backdrop at the top and bottom. This is the ‘cosmic microwave background radiation’ (CMBR). It is the oldest light in the Universe, the remains of the fireball out of which our Universe sprang into existence 13.7 billion years ago.

While the Milky Way shows us what the local Universe looks like now, those the microwave pattern is the cosmic blueprint from which today’s clusters and superclusters of galaxies were built. The different colours represent minute
differences in the temperature and density of matter across the sky. Somehow these small irregularities evolved into denser regions that became the galaxies of today.
The CMBR covers the entire sky but most of it is hidden in this image by the Milky Way’s emission, which must be digitally removed from the final data in order to see the microwave background in its entirety.
When this work is completed, Planck will show us the most precise picture of the microwave background ever obtained. The big question will be whether the data will reveal the cosmic signature of the primordial period called inflation.
This era is postulated to have taken place just after the Big Bang and resulted in the Universe expanding enormously in size over an extremely short period.
Planck continues to map the Universe. By the end of its mission in 2012, it will have completed four all-sky scans. The first full data release of the CMBR is planned for 2012. Before then, the catalogue containing individual objects in our
Galaxy and whole distant galaxies will be released in January 2011.
“This image is just a glimpse of what Planck will ultimately see,” says Jan Tauber, ESA’s Planck Project Scientist.(read more)

Source: Royal Astronomical Society

Many of the Milky Way’s ancient stars are remnants of other smaller galaxies torn apart by violent galactic collisions around five billion years ago, according to researchers at Durham University, who publish their results in a new paper in the journal Monthly Notices of the Royal Astronomical Society. (read more)

Source: ESA

Giant filaments of cold dust stretching through our Galaxy are revealed in a new image from ESA’s Planck satellite. Analyzing these structures could help to determine the forces that shape our Galaxy and trigger star formation.(read more)

Source: arXiv:1001.2521v1

The formation and evolution of the Galactic bulge and its relationship with the other Galactic populations is still poorly understood.

To establish the chemical differences and similarities between the bulge and other stellar populations, the astronomers have performed elemental abundance analysis of oxygen, magnesium, silicon, calcium, titanium, sodium and aluminium of red giant stars in the bulge as well as of local thin disk, thick disk and halo giants (see figure).

The authors used high-resolution optical spectra of 25 bulge giants in Baade’s window and made a comparison with 55 giants (4 halo, 29 thin disk and 22 thick disk giants) in the solar neighbourhood.

Baade’s Window is named after the German astronomer Walter Baade and lies towards the constellation of Sagittarius. This region has relatively low amounts of interstellar “dust” along our line of sight and is a “window” because in this direction we are able to see all the way to the Milky Way Galactic Center and beyond. Therefore it is used to inspect distant stars and to determine the internal geometry of the Milky Way. Using bulge giants and giants in our neighbourhood the authors could compare the inner structure of the Galaxy with our vicinity.

The authors have found that all stars have similar stellar parameters but cover a broad range in metallicity. In astronomy, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium. Since stars, which comprise most of the visible matter in the universe, are composed mostly of hydrogen and helium, astronomers, for convenience’s sake, use the blanket term “metal” to describe all other elements collectively.

The team of astronomers was able to confirm the well-established differences for [α /Fe] at a given metallicity between the local thin and thick disks. For all the elements investigated, they found no chemical distinction between the bulge and the local thick disk.

Their findings lead to the conclusion that the bulge and local thick disk stars experienced similar formation timescales, star formation rates and initial mass functions. The scientific team thinks that the identical types of stars that can be found on the thick disk and bulge stars may reflect a rapid chemical evolution taking place before the bulge and thick disk structures we see today were formed, or it may reflect Galactic orbital migration of inner disk/bulge stars resulting in stars in the solar neighbourhood with thick-disk kinematics.

This reasearch was accepted for publication byAstronomy & Astrophysics.(read more)

Links:
Original paper:Alves-Brito,A., Melendez,J., Asplund,M., Ramirez,I., Yong,D. (2010) Chemical similarities between Galactic bulge and local thick disk red giants: O, Na, Mg, Al, Si, Ca and Ti, Astronomy & Astrophysics, in press.

Source: Chandra@Harvard

Supermassive black hole Sgr A* and its surrounding region.
Credit: NASA/CXC/MIT/F. Baganoff, R. Shcherbakov et al.

Astronomers have long known that the supermassive black hole at the center of the Milky Way Galaxy, known as Sagittarius A* (or Sgr A* for short), is a particularly poor eater. (read more)

Related Links:
Chandra at NASA