Collisional processes in extrasolar planetesimal discs
... down to the radiation pressure blow-out limit Dmin (i.e. those for which β = Frad /Fgrav > 0.5), below which the distribution is cut-off. A sharp cut-off below Dmin is, however, a simplification. For a start, a sharp cut-off would cause a ‘wave’ in the equilibrium size distribution (Durda, Greenberg ...
... down to the radiation pressure blow-out limit Dmin (i.e. those for which β = Frad /Fgrav > 0.5), below which the distribution is cut-off. A sharp cut-off below Dmin is, however, a simplification. For a start, a sharp cut-off would cause a ‘wave’ in the equilibrium size distribution (Durda, Greenberg ...
Slides - AO4ELT3
... Simulation of a protoplanetary system with a tidal gap created by a Jupiter-like planet at 7 AU from its central star as observed by ALMA TMT’s Planet Formation Instrument (PFI) will allow detection of the planets themselves that are responsible for the gaps and thus enable measurements of mass, acc ...
... Simulation of a protoplanetary system with a tidal gap created by a Jupiter-like planet at 7 AU from its central star as observed by ALMA TMT’s Planet Formation Instrument (PFI) will allow detection of the planets themselves that are responsible for the gaps and thus enable measurements of mass, acc ...
IDEA MAN
... to study mathematics, engineering, and physics. With World War I raging, Switzerland provided a haven for many of Europe’s greatest minds. Zwicky met Albert Einstein, Wolfgang Pauli, and Vladimir Lenin. After graduation, Zwicky stayed on to pursue a degree in theoretical physics. His thesis applied ...
... to study mathematics, engineering, and physics. With World War I raging, Switzerland provided a haven for many of Europe’s greatest minds. Zwicky met Albert Einstein, Wolfgang Pauli, and Vladimir Lenin. After graduation, Zwicky stayed on to pursue a degree in theoretical physics. His thesis applied ...
Lyman-alpha imaging of starburst galaxies in the local universe and beyond Matthew Hayes
... we do understand comes from observations of the stars; by observing the radiation they produce directly, by observing reprocessed stellar energy, or by observing the violent phenomena in the final stages of stellar evolution. All but a very small fraction of stars in the universe reside in the confi ...
... we do understand comes from observations of the stars; by observing the radiation they produce directly, by observing reprocessed stellar energy, or by observing the violent phenomena in the final stages of stellar evolution. All but a very small fraction of stars in the universe reside in the confi ...
The dark matter crisis: falsification of the current standard model of
... perhaps gas is a galaxy if its Newtonian median twobody relaxation time is longer than the Hubble time, trel > τH ≈ 104 Myr. This definition of a galaxy (Kroupa 1998, 2008; Forbes & Kroupa 2011) naturally accounts for the dynamical process of energy equipartition not playing a role in galaxies over t ...
... perhaps gas is a galaxy if its Newtonian median twobody relaxation time is longer than the Hubble time, trel > τH ≈ 104 Myr. This definition of a galaxy (Kroupa 1998, 2008; Forbes & Kroupa 2011) naturally accounts for the dynamical process of energy equipartition not playing a role in galaxies over t ...
Stellar Intensity Interferometry: The Background John Davis Sydney Institute for Astronomy
... stars”. Robert Hanbury Brown (RHB) was determined to measure them • If these sources were galaxies their angular sizes would be of the order of a minute of arc and easy to measure with a conventional interferometer but, if they were stars, extremely long baselines would be needed and RHB concluded ...
... stars”. Robert Hanbury Brown (RHB) was determined to measure them • If these sources were galaxies their angular sizes would be of the order of a minute of arc and easy to measure with a conventional interferometer but, if they were stars, extremely long baselines would be needed and RHB concluded ...
Observed emission rates in sprite streamer heads
... range of 335 km, is 140 m. High resolution sprite observations by Gerken et al. [2000] show the transverse width of tendrils to be 10 s – 100 s of m. These observations were made at video rates and, assuming that the tendrils recorded are the optical signatures of compact, fast moving streamer head ...
... range of 335 km, is 140 m. High resolution sprite observations by Gerken et al. [2000] show the transverse width of tendrils to be 10 s – 100 s of m. These observations were made at video rates and, assuming that the tendrils recorded are the optical signatures of compact, fast moving streamer head ...
The growth of planets by pebble accretion in evolving protoplanetary
... The aim of this paper is to study the formation and evolution of planets in evolving accretion discs around young stars, where planets first grow via pebble accretion and can then contract a gaseous envelope. We focus here on the formation of different planetary types that can emerge in protoplaneta ...
... The aim of this paper is to study the formation and evolution of planets in evolving accretion discs around young stars, where planets first grow via pebble accretion and can then contract a gaseous envelope. We focus here on the formation of different planetary types that can emerge in protoplaneta ...
THE EVOLUTION OF GALAXY NUMBER DENSITY AT Z < 8 AND
... The primary method we use to determine the number densities of galaxies in the universe is to integrate through the fitted mass functions the number of galaxies which are at a given redshift. This requires extrapolating fitted stellar mass functions to reach down to a low mass limit of the galaxy po ...
... The primary method we use to determine the number densities of galaxies in the universe is to integrate through the fitted mass functions the number of galaxies which are at a given redshift. This requires extrapolating fitted stellar mass functions to reach down to a low mass limit of the galaxy po ...
Astronomy Astrophysics Excitation of solar-like oscillations across the HR diagram &
... a Lorentzian χk yield a slope, sv, closer to the observed one than the slope obtained when assuming a Gaussian. We show that the spatial resolution of the 3D simulations must be high enough to obtain accurate computed energy rates. Key words. convection – turbulence – Sun: oscillations – Hertzsprung ...
... a Lorentzian χk yield a slope, sv, closer to the observed one than the slope obtained when assuming a Gaussian. We show that the spatial resolution of the 3D simulations must be high enough to obtain accurate computed energy rates. Key words. convection – turbulence – Sun: oscillations – Hertzsprung ...
Power Point Presentation
... Neutron stars are supported by pressure from degenerate neutrons, formed from collapsed electrons and protons A teaspoonful of neutron star would weigh 1 billion ...
... Neutron stars are supported by pressure from degenerate neutrons, formed from collapsed electrons and protons A teaspoonful of neutron star would weigh 1 billion ...
My Thesis - Uppsala Astronomical Observatory
... the fundamental properties of low-mass stars. Observations of low-mass stars in detached eclipsing binaries (DEBs) indicate that stellar models under-predict real stellar radii by 5 – 10% and predict effective temperatures that are 3 – 5% too hot. This dissertation provides a careful examination of ...
... the fundamental properties of low-mass stars. Observations of low-mass stars in detached eclipsing binaries (DEBs) indicate that stellar models under-predict real stellar radii by 5 – 10% and predict effective temperatures that are 3 – 5% too hot. This dissertation provides a careful examination of ...
Luminosity profiles and sizes of massive star clusters in NGC 7252
... W30, respectively. We compare these extended profiles with those of YMCs in the Large Magellanic Cloud (R136 in 30 Dor), the Antennae galaxies (Knot S) and in the nearby spiral galaxy NGC 6946. Extended profiles seem to be a somewhat common feature, even though many nearby YMCs show distinct truncat ...
... W30, respectively. We compare these extended profiles with those of YMCs in the Large Magellanic Cloud (R136 in 30 Dor), the Antennae galaxies (Knot S) and in the nearby spiral galaxy NGC 6946. Extended profiles seem to be a somewhat common feature, even though many nearby YMCs show distinct truncat ...
3D LTE spectral line formation with scattering in red giant stars
... The physics of line formation involves many different processes that require a detailed treatment of the interaction between radiation and matter. Beside the transition itself, these processes include, e.g., Doppler-shifts through thermal and nonthermal particle motion, collisional interaction, photo ...
... The physics of line formation involves many different processes that require a detailed treatment of the interaction between radiation and matter. Beside the transition itself, these processes include, e.g., Doppler-shifts through thermal and nonthermal particle motion, collisional interaction, photo ...
Infrared identification of high-mass X
... The Na i emission line suggests the presence of a low-excitation region that is not directly exposed to the radiation of the star or the compact object. It is probably the signature of an extended circumbinary envelope (McGregor et al. 1988). A feature at 2.1226 µm might be associated with the molec ...
... The Na i emission line suggests the presence of a low-excitation region that is not directly exposed to the radiation of the star or the compact object. It is probably the signature of an extended circumbinary envelope (McGregor et al. 1988). A feature at 2.1226 µm might be associated with the molec ...
Star formation
Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as ""stellar nurseries"" or ""star-forming regions"", collapse to form stars. As a branch of astronomy, star formation includes the study of the interstellar medium (ISM) and giant molecular clouds (GMC) as precursors to the star formation process, and the study of protostars and young stellar objects as its immediate products. It is closely related to planet formation, another branch of astronomy. Star formation theory, as well as accounting for the formation of a single star, must also account for the statistics of binary stars and the initial mass function.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.