"The Probability and Effects of an Asteroid Impact with Earth"
... 666 km over which the temperature changes by one scale factor and where T = 5770 K has been used as a typical region of the solar atmosphere. Clearly it is safe to assume that most regions of the solar atmosphere are in LTE. Exceptions are restricted to regions where the temperature changes rapidl ...
... 666 km over which the temperature changes by one scale factor and where T = 5770 K has been used as a typical region of the solar atmosphere. Clearly it is safe to assume that most regions of the solar atmosphere are in LTE. Exceptions are restricted to regions where the temperature changes rapidl ...
Observational studies of stellar rotation
... In the Fourier domain, the convolution product becomes an arithmethic product, and the Fourier transform of G(λ) has the interesting property of having successive zeroes at frequencies inversely proportional to v sin i (e.g., Dravins et al. 1990), with the first zero occuring at ν1 ' (2/3)(c/λo ) · ...
... In the Fourier domain, the convolution product becomes an arithmethic product, and the Fourier transform of G(λ) has the interesting property of having successive zeroes at frequencies inversely proportional to v sin i (e.g., Dravins et al. 1990), with the first zero occuring at ν1 ' (2/3)(c/λo ) · ...
Proposal submitted to ISSI
... accretion shock where matter is falling down onto the protostellar surface. Average densities in observed young disks are quite often higher than 106 cm-3, which are typical number densities for planetary exospheres. Although the time scales for their dispersal is quite uncertain, most young stars w ...
... accretion shock where matter is falling down onto the protostellar surface. Average densities in observed young disks are quite often higher than 106 cm-3, which are typical number densities for planetary exospheres. Although the time scales for their dispersal is quite uncertain, most young stars w ...
Transiting planets from WASP
... evolved. Consequently, they have relatively large radii (R = 1.7−2.1 R ), translating into long (5–6 h) and low-amplitude transits for the three planets: ∼0.6% for WASP-68 b, ∼0.3% for WASP-73 b (the shallowest transits yet for a WASP planet), and ∼0.7% for WASP-88 b. Their detection demonstrates, ...
... evolved. Consequently, they have relatively large radii (R = 1.7−2.1 R ), translating into long (5–6 h) and low-amplitude transits for the three planets: ∼0.6% for WASP-68 b, ∼0.3% for WASP-73 b (the shallowest transits yet for a WASP planet), and ∼0.7% for WASP-88 b. Their detection demonstrates, ...
Type I SuperNova
... outer shells of the companion is transferred to the surface of the dwarf. Helium will then begin to accrete on the surface of the dwarf. Helium requires much higher temperature to fuse, and this higher temperature explosive fusion might be enough to drive the core to rapid carbon/oxygen fusion. When ...
... outer shells of the companion is transferred to the surface of the dwarf. Helium will then begin to accrete on the surface of the dwarf. Helium requires much higher temperature to fuse, and this higher temperature explosive fusion might be enough to drive the core to rapid carbon/oxygen fusion. When ...
10 New Constellations
... the primary component is a blue star with a radius 3 times greater than our sun with surface temperatures more than twice as hot. Alpheratz is officially the brightest star in Andromeda, it is also considered as part of Pegasus as it connects both constellations. M31 The most interesting object in t ...
... the primary component is a blue star with a radius 3 times greater than our sun with surface temperatures more than twice as hot. Alpheratz is officially the brightest star in Andromeda, it is also considered as part of Pegasus as it connects both constellations. M31 The most interesting object in t ...
Slide 1
... When a star dies, if the core has less mass than 1.4 times the sun, it will form a white dwarf. Gravity is trying to squeeze the core as small as it can get. It's stopped by the pressure of electrons trying to repel each other. This pressure counteracts gravity. Over billions of years, this hot core ...
... When a star dies, if the core has less mass than 1.4 times the sun, it will form a white dwarf. Gravity is trying to squeeze the core as small as it can get. It's stopped by the pressure of electrons trying to repel each other. This pressure counteracts gravity. Over billions of years, this hot core ...
STAR FORMATION IN ISOLATED DISK GALAXIES. II. SCHMIDT
... gas in the disk Qsg derived by Rafikov (2001). Galaxies with high initial mass or gas fraction have small Qsg and are more unstable, forming stars quickly, while stable galaxies with Qsg > 1 maintain quiescent star formation over a long time. Paper I emphasized that to form a stable disk and derive ...
... gas in the disk Qsg derived by Rafikov (2001). Galaxies with high initial mass or gas fraction have small Qsg and are more unstable, forming stars quickly, while stable galaxies with Qsg > 1 maintain quiescent star formation over a long time. Paper I emphasized that to form a stable disk and derive ...
Hertzsprung–Russell diagram - Wikipedia, the free encyclopedia
... that stars collapsed from red giants to dwarf stars, then moving down along the line of the main sequence in the course of their lifetimes. Stars were thought therefore to radiate energy by converting gravitational energy into radiation through the Kelvin–Helmholtz mechanism. This mechanism resulted ...
... that stars collapsed from red giants to dwarf stars, then moving down along the line of the main sequence in the course of their lifetimes. Stars were thought therefore to radiate energy by converting gravitational energy into radiation through the Kelvin–Helmholtz mechanism. This mechanism resulted ...
MESSIER - EarthLink
... His first own deep sky discovery of globular cluster M3, cataloged on May 3, probably causes him to undertake a systematical search for nebulous objects, leading to the observation and recording of the objects M3-M40, many of which were own discoveries, but several from old catalogs. Messier was mad ...
... His first own deep sky discovery of globular cluster M3, cataloged on May 3, probably causes him to undertake a systematical search for nebulous objects, leading to the observation and recording of the objects M3-M40, many of which were own discoveries, but several from old catalogs. Messier was mad ...
ABOUT PARALLAX AND… CONSTELLATIONS Abstract
... Cristina Palici di Suni suggests another possibility for a 3D model of parallax effect: it is the box shown in Figure 9. A teacher can prepare it in order to let the pupils understand that the parallax effect modifies the shape of a “constellation” of little balls on sticks if the point of view is m ...
... Cristina Palici di Suni suggests another possibility for a 3D model of parallax effect: it is the box shown in Figure 9. A teacher can prepare it in order to let the pupils understand that the parallax effect modifies the shape of a “constellation” of little balls on sticks if the point of view is m ...
Spinar Paradigm
... event. A spinar can be viewed as an intermediate state of a collapsing object whose lifetime is determined by the time scale of dissipation of the angular momentum. As Lipunova & Lipunov (1998) pointed out, the centrifugal barrier could explain the long (from several seconds to several hours) durati ...
... event. A spinar can be viewed as an intermediate state of a collapsing object whose lifetime is determined by the time scale of dissipation of the angular momentum. As Lipunova & Lipunov (1998) pointed out, the centrifugal barrier could explain the long (from several seconds to several hours) durati ...
EXPLORATION OF THE KUIPER BELT BY HIGH
... KBOs down to objects of 1 km radius leads to 1011 KBOs with a total mass of only 0.1 Mo (Gladman et al. 2001). In contrast, a simple extrapolation of the surface mass density of the solar system outside 35 AU yields several Earth masses. Moreover, KBO accretion models require an initial Kuiper Belt ...
... KBOs down to objects of 1 km radius leads to 1011 KBOs with a total mass of only 0.1 Mo (Gladman et al. 2001). In contrast, a simple extrapolation of the surface mass density of the solar system outside 35 AU yields several Earth masses. Moreover, KBO accretion models require an initial Kuiper Belt ...
Chapter 14 – Chemical Analysis
... • It is an ad hoc free parameter in the analysis, with values typically between 0.5 and 5 km/sec • Lower luminosity stars generally have lower values of microturbulence. • The microturbulence is determined as the value of x that makes the abundance independent of line ...
... • It is an ad hoc free parameter in the analysis, with values typically between 0.5 and 5 km/sec • Lower luminosity stars generally have lower values of microturbulence. • The microturbulence is determined as the value of x that makes the abundance independent of line ...
Lecture4
... A. Rigel: B8 ( T= 13,400K); Ia (L= 58000 Lsun ), Supergiant (SG) B. Algol: B8 ( T= 13,400K); V (L= 100 Lsun ), Main Sequence (MS) Same color, same T, but different L. How to find the difference? Ans: Width of the spectral lines tells the difference Lines such as H and H , strong for B8 stars, ar ...
... A. Rigel: B8 ( T= 13,400K); Ia (L= 58000 Lsun ), Supergiant (SG) B. Algol: B8 ( T= 13,400K); V (L= 100 Lsun ), Main Sequence (MS) Same color, same T, but different L. How to find the difference? Ans: Width of the spectral lines tells the difference Lines such as H and H , strong for B8 stars, ar ...
Transiting exoplanets from the CoRoT space mission
... The central star was spectroscopically analyzed using the HARPS data set. Figure 8 shows a significant sample of the HARPS spectrum used for this analysis. By comparing the spectra with a grid of stellar templates, as described in Frasca et al. (2003) and Gandolfi et al. (2008), or using SME (Valent ...
... The central star was spectroscopically analyzed using the HARPS data set. Figure 8 shows a significant sample of the HARPS spectrum used for this analysis. By comparing the spectra with a grid of stellar templates, as described in Frasca et al. (2003) and Gandolfi et al. (2008), or using SME (Valent ...
DUSTY CIRCUMSTELLAR DISKS B. Zuckerman
... The most dramatic of these IR-bright, low-luminosity, stars are found in the TWA, specifically HD 98800 (K5), Hen3-600 (M2), and TW Hydrae itself (K7). At each star the dust optical depth, tau, is approximately 0.1 (Zuckerman & Becklin 1993a, Zuckerman et al. 1995a), an order of magnitude larger tha ...
... The most dramatic of these IR-bright, low-luminosity, stars are found in the TWA, specifically HD 98800 (K5), Hen3-600 (M2), and TW Hydrae itself (K7). At each star the dust optical depth, tau, is approximately 0.1 (Zuckerman & Becklin 1993a, Zuckerman et al. 1995a), an order of magnitude larger tha ...
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.