CV - iucaa
... workshop, Pune, February 2015 • “Observing facilities and time domain activities in India”, International Conference on Computational Physics — Global Observatory Network for Solar System Observations (GONSSO), Singapore, January 2015 • “Seeing what we hear: Electromagnetic counterparts to gravitati ...
... workshop, Pune, February 2015 • “Observing facilities and time domain activities in India”, International Conference on Computational Physics — Global Observatory Network for Solar System Observations (GONSSO), Singapore, January 2015 • “Seeing what we hear: Electromagnetic counterparts to gravitati ...
Planet formation Abstract Megan K Pickett and Andrew J Lim
... not entirely certain, it is on the order of or smaller than the timescale for core-accretion. Thus, by the time a core reaches the trigger mass, the nebular gas may have disappeared. There may be exposed cores of failed gas giants in the universe, but they are not among the extrasolar planets so far ...
... not entirely certain, it is on the order of or smaller than the timescale for core-accretion. Thus, by the time a core reaches the trigger mass, the nebular gas may have disappeared. There may be exposed cores of failed gas giants in the universe, but they are not among the extrasolar planets so far ...
Nobuyuki Kawai
... • many more target events for GW! • no regular “GRB”: how to identify? – may have delayed X-ray/optical afterglow ...
... • many more target events for GW! • no regular “GRB”: how to identify? – may have delayed X-ray/optical afterglow ...
Star Wreck
... Neutron stars are stable in a certain range of masses. Assuming Harrison–Wheeler equation of state, one obtains a lower limit on the mass Mmin ≈ 0.18M⊙ [18]. By the time the Q-balls annex 80% of the neutron star baryon number, a similar fraction of the star’s mass is radiated away with thermal neutr ...
... Neutron stars are stable in a certain range of masses. Assuming Harrison–Wheeler equation of state, one obtains a lower limit on the mass Mmin ≈ 0.18M⊙ [18]. By the time the Q-balls annex 80% of the neutron star baryon number, a similar fraction of the star’s mass is radiated away with thermal neutr ...
The Orbital Period Distribution of Wide Binary Millisecond Pulsars
... Pfahl et al. 2003). As an example of a ”best-fit” solution, we show the orbital period distribution resulting from a simulation in which we adopted a Maxwellian kick-velocity distribution with a velocity dispersion of 100 km/s, a commonenvelope ejection efficiency equal to 1, and an upper limit on t ...
... Pfahl et al. 2003). As an example of a ”best-fit” solution, we show the orbital period distribution resulting from a simulation in which we adopted a Maxwellian kick-velocity distribution with a velocity dispersion of 100 km/s, a commonenvelope ejection efficiency equal to 1, and an upper limit on t ...
Betelgeuse
... "We observe around 11 microns, the mid-infrared, where this long wavelength penetrates the dust and the narrow bandwidth avoids any spectral lines, and so we see the star relatively undistorted," said Townes. "We have also had the good fortune to have an instrument that has operated in a very simila ...
... "We observe around 11 microns, the mid-infrared, where this long wavelength penetrates the dust and the narrow bandwidth avoids any spectral lines, and so we see the star relatively undistorted," said Townes. "We have also had the good fortune to have an instrument that has operated in a very simila ...
Chapter 20. Galaxies
... As you worked out in one of your problem set questions (and review the answer sheet if you didn’t get it right!), if we observe v = constant, instead of a falling v, we can infer (assuming that laws of gravity still hold even over the great distances of a galaxy’s radius) that Mr must be growing wit ...
... As you worked out in one of your problem set questions (and review the answer sheet if you didn’t get it right!), if we observe v = constant, instead of a falling v, we can infer (assuming that laws of gravity still hold even over the great distances of a galaxy’s radius) that Mr must be growing wit ...
A model of low-mass neutron stars with a quark core
... matter. Our calculations of integrated parameters for superdense stars using this equation of state show that on the stable branch of the dependence of stellar mass on central pressure (dM/dPc > 0) in the range of low masses, a new local maximum with Mmax = 0.082 and R = 1251 km appears after the f ...
... matter. Our calculations of integrated parameters for superdense stars using this equation of state show that on the stable branch of the dependence of stellar mass on central pressure (dM/dPc > 0) in the range of low masses, a new local maximum with Mmax = 0.082 and R = 1251 km appears after the f ...
RESEARCH STATEMENT Chromospheres and winds
... planets and plays an important role in both stellar and galactic evolution. The mechanisms that drive winds from cool (.8000K) evolved stars such as K and early-M stars are not well known. Unlike hot stars, radiative acceleration of gaseous material in K stars is not large enough to drive a wind. Th ...
... planets and plays an important role in both stellar and galactic evolution. The mechanisms that drive winds from cool (.8000K) evolved stars such as K and early-M stars are not well known. Unlike hot stars, radiative acceleration of gaseous material in K stars is not large enough to drive a wind. Th ...
5 - White Dwarfs - University of Texas Astronomy
... conclusion is that the two stars must have been far apart initially, even though they are very close together now. What is necessary to perform this bit of stellar legerdemain is to find a way to drag the stars together. The mechanism proposed to accomplish this is the common envelope, described in ...
... conclusion is that the two stars must have been far apart initially, even though they are very close together now. What is necessary to perform this bit of stellar legerdemain is to find a way to drag the stars together. The mechanism proposed to accomplish this is the common envelope, described in ...
Determining the Stellar Spin Axis Orientation
... Recent interferometric observations have managed to determine the spin axis orientation for a handful of early-type fast-rotating stars (Monnier et al (2007) and deSouza et al (2003)). Indeed, fast rotating stars are theorized to present cases of gravitation-darkening, i.e. the equatorial latitude o ...
... Recent interferometric observations have managed to determine the spin axis orientation for a handful of early-type fast-rotating stars (Monnier et al (2007) and deSouza et al (2003)). Indeed, fast rotating stars are theorized to present cases of gravitation-darkening, i.e. the equatorial latitude o ...
Word - Department of Physics - Hong Kong University of Science
... Newton’s law of gravitation and some fluid dynamics. Since there are some limitations on the computer programming, the animation is actually different from the real situation. In order to overcome these, we have made several assumptions on the model of the accretion process described in the previou ...
... Newton’s law of gravitation and some fluid dynamics. Since there are some limitations on the computer programming, the animation is actually different from the real situation. In order to overcome these, we have made several assumptions on the model of the accretion process described in the previou ...
Calculate the Mass of the Milky Way Galaxy
... Few of the points fall exactly on the line. This is because all galaxies have some additional residual motion in addition to the pure expansion. This is referred to as the "cosmic velocity dispersion" or "cosmic scatter" and is probably due to the fact that the gas clouds that formed the galaxies al ...
... Few of the points fall exactly on the line. This is because all galaxies have some additional residual motion in addition to the pure expansion. This is referred to as the "cosmic velocity dispersion" or "cosmic scatter" and is probably due to the fact that the gas clouds that formed the galaxies al ...
Life Cycle of a Star Lesson Plan
... A white dwarf is very hot when it is formed, but since it has no source of energy, it will gradually radiate away its energy and cool down. This means that its radiation, which initially has a high color temperature, will lessen and redden with time. Over a very long time, a white dwarf will cool to ...
... A white dwarf is very hot when it is formed, but since it has no source of energy, it will gradually radiate away its energy and cool down. This means that its radiation, which initially has a high color temperature, will lessen and redden with time. Over a very long time, a white dwarf will cool to ...
Star Formation in Our Galaxy - Wiley-VCH
... Along with their gas, molecular clouds contain an admixture of small solid particles, the interstellar dust grains. These particles efficiently absorb light with wavelengths smaller than their diameters (about 0.1 µm) and reradiate this energy into the infrared. Regions where the dust effectively bl ...
... Along with their gas, molecular clouds contain an admixture of small solid particles, the interstellar dust grains. These particles efficiently absorb light with wavelengths smaller than their diameters (about 0.1 µm) and reradiate this energy into the infrared. Regions where the dust effectively bl ...
Lecture 24, The local group
... If dwarfs are building blocks for more massive galaxies, then old stellar populations in both should have similar properties. Also, oldest stars in massive galaxies must be as old as or younger than the oldest stars in dwarf galaxies. If cosmic reionization squelches star formation due to heati ...
... If dwarfs are building blocks for more massive galaxies, then old stellar populations in both should have similar properties. Also, oldest stars in massive galaxies must be as old as or younger than the oldest stars in dwarf galaxies. If cosmic reionization squelches star formation due to heati ...
The difficulty of forming large disk galaxies with small bulges
... The O was likely produced by star formation in the disk and ejected into the CGM. Only 0.3 Gyr of SF at the present rate would be enough to produce it if it were all ejected. It could have accumulated over many Gyr, or be leftover from early starbursts. An estimate of [O/Fe] (or other Fe-peak eleme ...
... The O was likely produced by star formation in the disk and ejected into the CGM. Only 0.3 Gyr of SF at the present rate would be enough to produce it if it were all ejected. It could have accumulated over many Gyr, or be leftover from early starbursts. An estimate of [O/Fe] (or other Fe-peak eleme ...
Gal - University of Rochester
... • This new model suggests that peanuts grow simultaneously with bars (differing from other models). • We don’t know which resonance is dominant, but if we figure it out we may learn about the vertical shapes of galaxy bulges. • We used a symmetrical bar, however warp modes may be important during ba ...
... • This new model suggests that peanuts grow simultaneously with bars (differing from other models). • We don’t know which resonance is dominant, but if we figure it out we may learn about the vertical shapes of galaxy bulges. • We used a symmetrical bar, however warp modes may be important during ba ...
Astronomy 730 / Galaxies
... zb. At t = t0 the boundary conditions are that σz(R, t0) = σz(0, t0) exp(−R/2hR) and hz(R, t0) = constant. If we take σz(R0,t0) = 20 km/s, we know that hz(R, t0) = 350 pc, again based on the old stars in the thin disk in the solar neighborhood. (c) Equate σz(R, t0) = σz(0, t0) exp(-R/2hR) with σz(R, ...
... zb. At t = t0 the boundary conditions are that σz(R, t0) = σz(0, t0) exp(−R/2hR) and hz(R, t0) = constant. If we take σz(R0,t0) = 20 km/s, we know that hz(R, t0) = 350 pc, again based on the old stars in the thin disk in the solar neighborhood. (c) Equate σz(R, t0) = σz(0, t0) exp(-R/2hR) with σz(R, ...
GRB jets and their interaction with the progenitor star
... opening angle of 10o and =10 is propagated through polytropic stars of varying mass and radius. The break-out time depends very mildly on the mass, so too the energy deposited into the star ...
... opening angle of 10o and =10 is propagated through polytropic stars of varying mass and radius. The break-out time depends very mildly on the mass, so too the energy deposited into the star ...
Observations with Herschel: High-mass star formation and the
... gas and dust between stars in galaxies – and how massive stars are able to form deep within the extremely large and ice cold gas clouds in the ISM. In Paper I, we present searches for a so far undetected key molecule in the interstellar nitrogen chemistry, NH+ , along with the anion NH− 2 . Despite ...
... gas and dust between stars in galaxies – and how massive stars are able to form deep within the extremely large and ice cold gas clouds in the ISM. In Paper I, we present searches for a so far undetected key molecule in the interstellar nitrogen chemistry, NH+ , along with the anion NH− 2 . Despite ...
Quasars
... lot of ultraviolet excess. • One of them, 3C273 had its position very accurately measured by C. Hazard and co-workers, using lunar occultations. • In 1962, M. Schmidt obtained a spectrum of this “object", which showed a large redshift of 0.158, indicative of being very far away according to Hubble‟s ...
... lot of ultraviolet excess. • One of them, 3C273 had its position very accurately measured by C. Hazard and co-workers, using lunar occultations. • In 1962, M. Schmidt obtained a spectrum of this “object", which showed a large redshift of 0.158, indicative of being very far away according to Hubble‟s ...
Cygnus X-1
Cygnus X-1 (abbreviated Cyg X-1) is a well-known galactic X-ray source, thought to be a black hole, in the constellation Cygnus. It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources seen from Earth, producing a peak X-ray flux density of 6977229999999999999♠2.3×10−23 Wm−2 Hz−1 (7003230000000000000♠2.3×103 Jansky). Cygnus X-1 was the first X-ray source widely accepted to be a black hole and it remains among the most studied astronomical objects in its class. The compact object is now estimated to have a mass about 14.8 times the mass of the Sun and has been shown to be too small to be any known kind of normal star, or other likely object besides a black hole. If so, the radius of its event horizon is about 7004440000000000000♠44 km.Cygnus X-1 belongs to a high-mass X-ray binary system about 7019574266339685654♠6070 ly from the Sun that includes a blue supergiant variable star designated HDE 226868 which it orbits at about 0.2 AU, or 20% of the distance from the Earth to the Sun. A stellar wind from the star provides material for an accretion disk around the X-ray source. Matter in the inner disk is heated to millions of degrees, generating the observed X-rays. A pair of jets, arranged perpendicular to the disk, are carrying part of the energy of the infalling material away into interstellar space.This system may belong to a stellar association called Cygnus OB3, which would mean that Cygnus X-1 is about five million years old and formed from a progenitor star that had more than 7001400000000000000♠40 solar masses. The majority of the star's mass was shed, most likely as a stellar wind. If this star had then exploded as a supernova, the resulting force would most likely have ejected the remnant from the system. Hence the star may have instead collapsed directly into a black hole.Cygnus X-1 was the subject of a friendly scientific wager between physicists Stephen Hawking and Kip Thorne in 1975, with Hawking betting that it was not a black hole. He conceded the bet in 1990 after observational data had strengthened the case that there was indeed a black hole in the system. This hypothesis has not been confirmed due to a lack of direct observation but has generally been accepted from indirect evidence.