Niraj D. Welikala Thesis - [email protected]
... and on these scales the density fluctuations are small in size (rms fluctuations of the order
∼ 0.1 at 1 Gpc). However, on scales of the order of 10 Mpc, the density fluctuations are large
(∼ 1). The most apparent overdensities are therefore on small scales, less than 10 Mpc which
are the typical sc ...
CoRoT III programme
... CoRoT has made many “premières” in both planet detection and stellar microvariability.
For instance CoRoT has discovered the first member of the new class of planets: Super-Earths
orbiting very close to their parent star. It has also discovered the first two brown dwarfs at
short orbital period and ...
my dissertation (PhD. Thesis) - Argelander
... • Galaxies at cosmological distances may show us how they are actually forming and how early
stages of galaxies looked like long (several Gigayear) ago. However these objects are very far
away, and thus appear very small and faint, so that observational constrictions blur the picture
severely. Thusf ...
The most metal-poor galaxies
... the process of formation, because of their extreme metal under-abundance, more than 10
times less than solar, and even more extreme than that of HII regions found in the outskirts
of spiral galaxies. At the time of this discovery the general wisdom that most galaxies (in
particular the ellipticals) ...
Unfolding the Milky Way bulge - International Max Planck Research
... Extinction map of the Galactic Bulge for the complete region covered by the
VVV survey. The AKs values are computed from E(J − K s ) measurements assuming Cardelli et al. (1989) extinction law for all tiles. At AKs values larger
than 1.5 mag the color scale saturates. The details of the extinction v ...
Article PDF - IOPscience
... morphological and physical evidence for undergoing higher
than average star formation as compared to galaxies in the
nearby universe, we examine the morphological properties
of ﬁve nearby starburst galaxies that are generally regarded
as the best analogs of high-redshift star-forming systems
Observational evidence for AGN feedback in early
... black hole is invoked to suppress star formation in early-type galaxies at later epochs. A major
problem is that this process is poorly understood, and compelling observational evidence for
its mere existence is still missing. In search for signatures of AGN feedback, we have compiled
a sample of 16 ...
The Lupus clouds - European Southern Observatory
... The Lupus clouds are projected on the sky against the nearest and one of the best studied OB associations, Scorpius-Centaurus (e.g. Blaauw 1991, de Geus et al. 1989, de
Geus 1992, Preibisch et al. 2002; see also chapter by Preibisch & Mamajek). The
Scorpius-Centaurus association is a vast complex in ...
... 24. Based on Student 2’s discussion, Algol B is part of the present Algol system because of which of the following
forces exerted on Algol B by the original Algol system?
F. Electric force
G. Magnetic force
H. Gravitational force
J. Nuclear force
25. Based on Student 1’s discussion and Fact 4, while ...
Mapping the Pathways of Galaxy Transformation Across Time and
... outcomes from the IMACS Cluster-Building Survey: our finding that most z∼0.5 poststarbursts are rejuvenated passive galaxies, and a simple model positing that every
galaxy has a lognormal SFH whose parameters are set at birth. Both studies reinterpreted key metrics of galaxy evolution typically seen ...
Evolution of galaxy morphology - Lecture 1 - NCRA-TIFR
... gravitationally bound agglomerations of stars, dust, gas, dark
Mass ratio Gas:Stars:Dark Matter - 1:10:100
they are the basic building blocks of the Universe on large scales
they show a broad range in their physical properties
Understanding of galaxy formation and evolution is one of the
THE UV-OPTICAL COLOR MAGNITUDE DIAGRAM. II. PHYSICAL
... We use the UV-optical color magnitude diagram in combination with spectroscopic and photometric measurements
derived from the SDSS spectroscopic sample to measure the distribution of galaxies in the local universe (z < 0:25) and
their physical properties as a function of specific star formation rate ...
Here - NASA/IPAC Extragalactic Database
... at which one is working). The effective temperatures T? of the ionizing stars lie in the
range 35 000 – 50 000 K. The nebular geometries result from the structure of the parent
molecular cloud. Stellar winds, at evolved stages, may produce ring-like structures, but
the morphology of H ii regions is ...
2. The X-ray-Radio correlation for bulgeless galaxies
... Correlations between the X-ray and Radio emissions are observed for both galaxies with
Active Galactic Nuclei (AGN) and in Star Forming galaxies. For the first case, the Xray/Radio correlation seems to present different slopes for Radio-loud and Radio-quiet
AGN and may be used to estimate the mass o ...
The nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System. It suggests that the Solar System formed from nebulous material. The theory was developed by Immanuel Kant and published in his Universal Natural History and Theory of the Heaven. Originally applied to our own Solar System, this process of planetary system formation is now thought to be at work throughout the universe. The widely accepted modern variant of the nebular hypothesis is the solar nebular disk model (SNDM) or simply solar nebular model. This nebular hypothesis offered explanations for a variety of properties of the Solar System, including the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun's rotation. Some elements of the nebular hypothesis are echoed in modern theories of planetary formation, but most elements have been superseded.According to the nebular hypothesis, stars form in massive and dense clouds of molecular hydrogen—giant molecular clouds (GMC). These clouds are gravitationally unstable, and matter coalesces within them to smaller denser clumps, which then rotate, collapse, and form stars. Star formation is a complex process, which always produces a gaseous protoplanetary disk around the young star. This may give birth to planets in certain circumstances, which are not well known. Thus the formation of planetary systems is thought to be a natural result of star formation. A Sun-like star usually takes approximately 1 million years to form, with the protoplanetary disk evolving into a planetary system over the next 10-100 million years.The protoplanetary disk is an accretion disk that feeds the central star. Initially very hot, the disk later cools in what is known as the T tauri star stage; here, formation of small dust grains made of rocks and ice is possible. The grains eventually may coagulate into kilometer-sized planetesimals. If the disk is massive enough, the runaway accretions begin, resulting in the rapid—100,000 to 300,000 years—formation of Moon- to Mars-sized planetary embryos. Near the star, the planetary embryos go through a stage of violent mergers, producing a few terrestrial planets. The last stage takes approximately 100 million to a billion years.The formation of giant planets is a more complicated process. It is thought to occur beyond the so-called frost line, where planetary embryos mainly are made of various types of ice. As a result, they are several times more massive than in the inner part of the protoplanetary disk. What follows after the embryo formation is not completely clear. Some embryos appear to continue to grow and eventually reach 5–10 Earth masses—the threshold value, which is necessary to begin accretion of the hydrogen–helium gas from the disk. The accumulation of gas by the core is initially a slow process, which continues for several million years, but after the forming protoplanet reaches about 30 Earth masses (M⊕) it accelerates and proceeds in a runaway manner. Jupiter- and Saturn-like planets are thought to accumulate the bulk of their mass during only 10,000 years. The accretion stops when the gas is exhausted. The formed planets can migrate over long distances during or after their formation. Ice giants such as Uranus and Neptune are thought to be failed cores, which formed too late when the disk had almost disappeared.