Archivi tag: star formation

Mind the Gap: from microphysics to large-scale structure in the Universe

Conference rationale is to bring together scientific communities working on theory and numerical simulations on small scales: star formation, (MHD) turbulence, radiative and accretion processes to talk to researchers working on large scale cosmological simulations. The aim is to share theoretical and numerical expertise to further interaction between these scientific communities; discuss the modelling of feedback processes on different scales with the following scopes:

  • pin down what are the most crucial physical processes at each scale for different systems
  • find novel ways to incorporate these processes by learning from small and large scale simulations both in terms of numerical techniques and of more realistic physical modelling (e.g. improved effective/sub-grid models for the scales beyond the dynamical range)

CARMA Symposium 2013

The Kavli Institute for Cosmological Physics (KICP) at the University of Chicago will host the 2013 CARMA Science Symposium on July 8-9, 2013. The two-day meeting will feature presentations relevant to the wide range of interdisciplinary science pursued with CARMA. In particular, there will be presentations from the community on potential future directions for CARMA-related research. These presentations include potential collaboration with new observatories, and science for which CARMA is uniquely suited.

New hints on primordial galaxies

Le galassie primordiali avevano un aspetto alquanto differente rispetto a quelle che popolano l’Universo oggi. Grazie ad una serie di osservazioni condotte con il Very Large Telescope (VLT) e il telescopio spaziale Hubble (HST), alcuni ricercatori hanno studiato una galassia molto antica, con una accuratezza senza precedenti, e da cui è stato possibile determinare alcuni parametri astrofisici che la caratterizzano, come la massa, la dimensione, il contenuto chimico e il tasso di formazione stellare.

Galaxies are deeply fascinating objects. The seeds of galaxies are quantum fluctuations in the very early Universe and thus, understanding of galaxies links the largest scales in the Universe with the smallest. It is only within galaxies that gas can become cold and dense enough to form stars and galaxies are therefore the cradles of starsbirths”, explains Johan Fynbo, professor at the Dark Cosmology Centre at the Niels Bohr Institute at the University of Copenhagen. Early in the Universe, galaxies were formed from large clouds of gas and dark matter. Gas is the Universe’s raw material for the formation of stars. Inside galaxies the gas can cool down from the many thousands of degrees it has outside galaxies. When gas is cooled it becomes very dense. Finally, the gas is so compact that it collapses into a ball of gas where the gravitational compresion heats up the matter, creating a glowing ball of gas, a star is born. In the red-hot interior of massive stars, hydrogen and helium melt together and form the first heavier elements like carbon, nitrogen, oxygen, which go on to form magnesium, silicon and iron. When the entire core has been converted into iron, no more energy can be extracted and the star dies as a supernova explosion. Every time a massive star burns out and dies, it hence flings clouds of gas and newly formed elements out into space, where they form gas clouds that get denser and denser and eventually collapse to form new stars. The early stars contained only a thousandth of the elements found in the Sun today. In this way, each generation of stars becomes richer and richer in heavy elements. In today’s galaxies, we have a lot of stars and less gas. In the early galaxies, there was a lot of gas and fewer stars. “We want to understand this cosmic evolutionary history better by studying very early galaxies. We want to measure how large they are, what they weigh and how quickly stars and heavy elements are formed”, explains Johan Fynbo.

The research team has studied a galaxy located approximately 11 billion years back in time in great detail.

Behind the galaxy is a quasar, which is an active black hole that is brighter than a galaxy. Using the light from the quasar, they found the galaxy using the giant telescopes, VLT in Chile. The large amount of gas in the young galaxy simply absorbed a massive amount of the light from the quasar lying behind it. Here they could ‘see’, via absorption, the outer parts of the galaxy. Furthermore, active star formation causes some of the gas to light up, so it could be observed directly. With the Hubble Space Telescope they could also see the recently formed stars in the galaxy and they could calculate how many stars there were in relation to the total mass, which is comprised of both stars and gas. They could now see that the relative proportion of heavier elements is the same in the centre of the galaxy as in the outer parts and it shows that the stars that are formed earlier in the centre of the galaxy enrich the stars in the outer parts with heavier elements. “By combining the observations from both methods – absorption and emission – we have discovered that the stars have an oxygen content equivalent to approx. 1/3 of the Sun’s oxygen content. This means that earlier generations of stars in the galaxy had already built up elements that made it possible to form planets like Earth 11 billion years ago”, conclude Johan Fynbo.

University of Copenaghen: New knowledge about early galaxies
arXiv: Comprehensive Study of a z = 2:35 DLA Galaxy: Mass, Metallicity, Age, Morphology and SFR from HST and VLT

10° Pacific Rim Conference on Stellar Astrophysics

The conference will be held from May 27 to May 31, 2013. New results and various aspects of stellar astrophysics will be presented and discussed by the participants from all over the world including the countries of the pacific rim.

Topics:

  • Stellar structure; interior, atmosphere, evolution, chemical abundance
  • Multiple stellar systems
  • Variable stars
  • Planetary Nebulae and Symbiotic Stars
  • Cataclysmic variables
  • Compact stars and Supernovae
  • Star Formation
  • Exoplanets

Brown Dwarfs come of Age

An international conference on Brown Dwarfs will be held next May in the sunny island of Fuerteventura, exactly 11 years after the first IAU Symposium devoted to these once elusive objects and 18 years after the definitive observational confirmation of their existence. Much work has been done in the last two decades, both from the theoretical and observational point of view. Time is ripe now to have a conference to provide a comprehensive overview of this very active field of research. Some of the most relevant work on Brown Dwarfs has been done in the Canarian Observatories, making Canary Islands an ideal location to host this conference. Fuerteventura is the easternmost island of the Canaries, rich of unique natural spaces and impressive landscapes. It is well connected by direct flights with many European cities and offers many possibilities of affordable and comfortable accommodation. This island is working to preserve its dark night sky and become a Starlight Reserve.

Wide-area surveys such as DENIS, SDSS and 2MASS have played a major role in the discoveries of some of the first brown dwarfs and the definition of the spectral classes L and T. Recently completed and ongoing surveys such as IPHAS, PANSTARS, UKIDSS and WISE are shedding new light on the field. An even cooler spectral class, the Y dwarfs, has been revealed. Detailed studies of brown dwarfs have uncovered surprising behaviours such as ultra-fast rotation rates, the presence of clouds, polarization and strong radio emission. Observations of dust in disks around very low-mass primaries with the Spitzer and Herschel satellites have provided information on the conditions of planet formation. Brown dwarfs have become prime interest targets for searches for habitable planets due to their small masses and radii, and the presence of a habitable regions very close to them for extended periods of time. Brown dwarfs populate the natural bridge between stars and planets. As such, they are connected with both types of objects. One of the main focus of this international conference will be to examine whether the fundamental properties of brown dwarfs represent a smooth continuity from stars to planets or not. Brown dwarfs and their extension into planetary masses represent the low-mass end of the stellar IMF. Deep observations of young open clusters and star-forming regions and microlensing surveys have found a population of very low-mass brown dwarfs or free-floating planets.

Our conference will provide a comprehensive update of the status of this active field of research. Here is a list of the scientific topics that will be treated:

  • Formation and early evolution of brown dwarfs
  • Angular momentum and disk evolution in very low mass systems
  • Large scale surveys
  • Deep surveys
  • Brown dwarfs in binary systems
  • The lower end of the IMF
  • Planets around brown dwarfs
  • Ultracool atmospheres
  • Spectroscopy of brown dwarfs
  • Time domain phenomena in brown dwarfs: activity and weather
  • Oncoming and future projects in the substellar world
  • The brown dwarfs-exoplanet connection

The Modern Radio Universe 2013

80 years ago, in spring 1933, Karl Jansky published his discovery of cosmic radio emission. This paved the way not only for a new discipline, radio astronomy, but also for an exploration of the universe that now encompasses almost the entire electromagnetic window. Today, radio astronomy is about to enter into yet another new era with a number of new or upgraded radio facilities coming online and major new initiatives, like the Square Kilometre Array (SKA), are starting up. This conference will try to highlight the original and exciting science currently being produced by radio astronomical telescopes, such as the GBT, Effelsberg, LOFAR, ALMA, the JVLA, GMRT, eMERLIN, EVN, VLBA, as well as pathfinder experiments of the SKA, and others.
Science areas that will be discussed are among others: Cosmology, galaxy evolution, AGN and compact objects, star formation, interstellar medium, The Milky Way and Galactic science, radio transients, fundamental and astroparticle physics, extreme physics and associated theory. This fresh view on the radio universe will improve our current knowledge of the universe and highlight new trends in radio astronomy. The science delivered by the radio astronomical community addresses key questions in modern astrophysics that may lead us to even more ambitious science goals to be targeted by future radio facilities like the SKA.
The last Modern Radio Universe took place 2007 in Manchester commemorating 50 years of the Lovell telescope and looking forward towards the SKA. This issue of the conference commemorates the groundbreaking work of Karl Jansky 80 years ago and comes 40 years after the Effelsberg 100 metre telescope started operations. While combining past and future in this conference, the main focus of the science presentations, however, will be to make an inventory of outstanding science results that are presently being obtained with the new or upgraded facilities.

Caffau’s star, an astrophysical mystery

SDSS J102915 172927 as seen by ESO – VLT

To ordinary people, stars in the galaxy may seem like tiny specks of light. But to Penn State Brandywine Professor Timothy Lawlor and undergraduate researcher Nick Rufo, one of those bright balls of gas is actually more massive than scientists originally reported and holds implications for understanding the evolution of the Universe.

Research conducted by Rufo and Lawlor about the irregular characteristics of what is known as “Caffau’s Star” suggests that it could actually be considered part of the subgiant category rather than a main sequence star. This means that Caffau’s Star could actually be much more immense than initially described. This finding plays an important role in strengthening the understanding of star formation and helps researchers comprehend the evolution of the 13.8 billion-year-old Universe. “The puzzle of stellar evolution is really about the origin of every one of us”, explained Lawlor. “One of the most fascinating things about stellar evolution and the evolution of the Universe is how it becomes clear that a huge majority of all atoms that make up you, me and the entire planet can be traced back to the center of a very massive star that blew up long ago”. Rufo, who spent his first two years at the Brandywine campus and is now a meteorology major in the College of Earth and Mineral Sciences at University Park, worked closely with Lawlor to analyze data about Caffau’s Star. He was able to complete calculations using a computer code and produced all of the models that were compared to Caffau’s Star in the research process. “Nicholas was a dedicated researcher” Lawlor said. “He helped uncover that the mass did not fit that of a main sequence star, and that for the observed composition of lithium to match, the star would have to be significantly less massive, which was not likely based on the temperature. Working with Nicholas was one of the most productive collaborations I have had with an undergraduate researcher”. While at the campus, Rufo participated in Penn State Brandywine’s spring undergraduate research exhibition called EURECA, where he presented the beginning discoveries of the studies he conducted alongside Lawlor. “I feel honored to have worked with a great professor like Dr. Lawlor”, Rufo said. “I never imagined I would have an opportunity working with Dr. Lawlor on a paper and doing research on a fascinating subject like astronomy when I was a student at Brandywine. I really enjoyed the experience and feel it gave me confidence and motivation”.

Penn State University: Student and professor solve astronomical mystery
arXiv: The extremely low metallicity star SDSS J102915+172927: a subgiant scenario

From Stars to Life

From Stars to Life – Connecting our understanding of star formation, planet formation, astrochemistry and astrobiology. Science topics: Star Formation (including isolated and clustered star formation), Circumstellar Disks, Planet Formation, Exoplanets (including search and characterization), Solar System constraints, Astrochemistry, Prebiotic Chemistry. We would like to understand the physical and chemical processes that lead to habitable planet formation, starting from the simplest interstellar medium initial conditions of pre-stellar cores, through star formation, accretion & protoplanetary disk evolution, and planet & planetary system formation & evolution. We will discuss theoretical, observational and laboratory constraints on these processes. The conference aims to foster inter and multidisciplinary collaboration between researchers interested in these topics.

The TAIPAN Survey: Toward the Next Generation of Spectroscopic All-Sky Surveys

The TAIPAN Survey: Toward the Next Generation of Spectroscopic All-Sky Surveys – The workshop is designed to bring together experts and researchers to discuss the science prospects and goals of the proposed TAIPAN survey.  Continua a leggere The TAIPAN Survey: Toward the Next Generation of Spectroscopic All-Sky Surveys