Formation Process of the Circumstellar Disk
... the star formation process, and the dynamics of disks may determine the mass accretion rate onto the protostar that determines the final stellar mass. In addition, planets are considered to form in the circumstellar (or protoplanetary) disk, and their formation process strongly depends on disk proper ...
... the star formation process, and the dynamics of disks may determine the mass accretion rate onto the protostar that determines the final stellar mass. In addition, planets are considered to form in the circumstellar (or protoplanetary) disk, and their formation process strongly depends on disk proper ...
Coordinate Systems - AST 114, Astronomy Lab II for Spring 2017!
... Because RA and Dec are coordinates fixed to the sky, stars and other distant objects will keep their location in right ascension and declination throughout the year (just like we stay at the same latitude and longitude here in Tempe). Take, for example, the star Betelgeuse, in the Orion constellatio ...
... Because RA and Dec are coordinates fixed to the sky, stars and other distant objects will keep their location in right ascension and declination throughout the year (just like we stay at the same latitude and longitude here in Tempe). Take, for example, the star Betelgeuse, in the Orion constellatio ...
Properties of Galactic early-type O
... mass-loss rate in the presence of clumping. The uncertainty in the true value of the mass-loss rate translates in a corresponding uncertainty in the evolutionary tracks of massive stars. Recent studies showed that winds are clumped, although there is no consensus concerning the amount, nature (optic ...
... mass-loss rate in the presence of clumping. The uncertainty in the true value of the mass-loss rate translates in a corresponding uncertainty in the evolutionary tracks of massive stars. Recent studies showed that winds are clumped, although there is no consensus concerning the amount, nature (optic ...
Determination of the distance to the Andromeda Galaxy using variable stars U
... tions revealed its complex spiral structure, probably due to interactions with its numerous satellite galaxies. Other studies have revealed a rich stellar population (Massey, 2003) with all types of massive stars (e.g. main sequence stars, WolfRayets, Luminous Blue Variable stars, Red Supergiants, e ...
... tions revealed its complex spiral structure, probably due to interactions with its numerous satellite galaxies. Other studies have revealed a rich stellar population (Massey, 2003) with all types of massive stars (e.g. main sequence stars, WolfRayets, Luminous Blue Variable stars, Red Supergiants, e ...
Three-dimensional simulations of the atmosphere of an AGB star
... The models cover a spherical shell with an inner boundary below the stellar photosphere but above the driving zone of stellar pulsations. The effects of pulsations (or, in the present case, large-scale convection) are simulated by temporal variations at the inner boundary. The location of the outer ...
... The models cover a spherical shell with an inner boundary below the stellar photosphere but above the driving zone of stellar pulsations. The effects of pulsations (or, in the present case, large-scale convection) are simulated by temporal variations at the inner boundary. The location of the outer ...
AMUSE-Virgo AGN Multi-wavelength Survey
... - 84 new targets with Chandra ACIS-S (454 ksec; PI: Treu) + 16 archival - 57 new targets with Spitzer MIPS (9.5 hr) + 43 archival - HST ACS archival data (100 orbits) - VLA, in progress (with D. Axon) ...
... - 84 new targets with Chandra ACIS-S (454 ksec; PI: Treu) + 16 archival - 57 new targets with Spitzer MIPS (9.5 hr) + 43 archival - HST ACS archival data (100 orbits) - VLA, in progress (with D. Axon) ...
Scales of Space and Time
... 90% of the volume or look-back time is probed by deep field 90% of the galaxies in the volume are counted ...
... 90% of the volume or look-back time is probed by deep field 90% of the galaxies in the volume are counted ...
the mass-loss return from evolved stars to the large
... giant branch (O-rich AGB) stars in the Large Magellanic Cloud (LMC) using radiative transfer (RT) models of dust shells around stars. We chose a star from each of the bright and faint O-rich AGB populations found by earlier studies of the SAGE sample in order to derive a baseline set of dust propert ...
... giant branch (O-rich AGB) stars in the Large Magellanic Cloud (LMC) using radiative transfer (RT) models of dust shells around stars. We chose a star from each of the bright and faint O-rich AGB populations found by earlier studies of the SAGE sample in order to derive a baseline set of dust propert ...
Finding high-redshift dark stars with the James Webb Space
... the dark matter halo (density and velocity structure). In particular, these dependencies are rather degenerate; the impact of a short equilibrium timescale can for example be mimicked by a denser dark matter halo. This picture is further complicated by the fact that accretion may also continue to so ...
... the dark matter halo (density and velocity structure). In particular, these dependencies are rather degenerate; the impact of a short equilibrium timescale can for example be mimicked by a denser dark matter halo. This picture is further complicated by the fact that accretion may also continue to so ...
The destruction and survival of polycyclic aromatic hydrocarbons in
... In Spitzer observations of Tauri stars and their disks, features of polycyclic aromatic hydrocarbons (PAHs) are detected in less than 10% of the objects, although the stellar photosphere is sufficiently hot to excite PAHs. To explain the deficiency, we discuss PAH destruction by photons, assuming that ...
... In Spitzer observations of Tauri stars and their disks, features of polycyclic aromatic hydrocarbons (PAHs) are detected in less than 10% of the objects, although the stellar photosphere is sufficiently hot to excite PAHs. To explain the deficiency, we discuss PAH destruction by photons, assuming that ...
highen_13_gravwaves - Mullard Space Science Laboratory
... • So no pair of orbiting bodies can emit more than 4x1052 W regardless of their mass • For the Earth around the Sun, about 200W are emitted – so our orbit should last another 1023 years before it decays by gravitational radiation • When dimensions of orbit approach the Schwarzschild radius, gravitat ...
... • So no pair of orbiting bodies can emit more than 4x1052 W regardless of their mass • For the Earth around the Sun, about 200W are emitted – so our orbit should last another 1023 years before it decays by gravitational radiation • When dimensions of orbit approach the Schwarzschild radius, gravitat ...
Small galaxies are growing smaller
... Shapley (see A&G 2003 45 1.18). Sculptor, in particular, was very much less luminous (by another factor ~100) than previously known galaxies – with modern distance estimates it has MV ≈ –10 – and these two were the first examples of dwarf spheroidal galaxies. They were discovered only because they w ...
... Shapley (see A&G 2003 45 1.18). Sculptor, in particular, was very much less luminous (by another factor ~100) than previously known galaxies – with modern distance estimates it has MV ≈ –10 – and these two were the first examples of dwarf spheroidal galaxies. They were discovered only because they w ...
![Module 4.1 - The Scale of the Universe [slide 1] We now turn to](http://s1.studyres.com/store/data/002846843_1-9e0ec9d1a2abbbab3c0d406694bfc4e2-300x300.png)
Module 4.1 - The Scale of the Universe [slide 1] We now turn to
... to distances to pulsating stars: Cepheids and so called RR-Lyrae Stars, which are a key step in the measurements of the Hubble Constant. But notice that several steps precede this. With those, we can measure distances to a number of nearby galaxies. And then we can calibrate distance indicator relat ...
... to distances to pulsating stars: Cepheids and so called RR-Lyrae Stars, which are a key step in the measurements of the Hubble Constant. But notice that several steps precede this. With those, we can measure distances to a number of nearby galaxies. And then we can calibrate distance indicator relat ...
The Milky Way disk
... Abstract / This review summarises the invited presentation I gave on the Milky Way disc. The idea underneath was to touch those topics that can be considered hot nowadays in the Galactic disk research: the reality of the thick disk, the spiral structure of the Milky Way, and the properties of the ou ...
... Abstract / This review summarises the invited presentation I gave on the Milky Way disc. The idea underneath was to touch those topics that can be considered hot nowadays in the Galactic disk research: the reality of the thick disk, the spiral structure of the Milky Way, and the properties of the ou ...
PDF - Department of Statistics
... the arithmetic mean and standard deviation in order to guard against occultations and aberrant outliers. Let Yksh denote the resulting test statistic for hold h of star s on telescope k. We now describe a test based on measurements at multiple telescopes which flags a star-hold if Yksh is sufficient ...
... the arithmetic mean and standard deviation in order to guard against occultations and aberrant outliers. Let Yksh denote the resulting test statistic for hold h of star s on telescope k. We now describe a test based on measurements at multiple telescopes which flags a star-hold if Yksh is sufficient ...
16. Hubble`s Law and Dark Matter
... 16.1 Dark Matter in the Universe • Galaxy mass measurements show that galaxies need between 3 and 10 times more mass than can be observed to explain their rotation curves. • The discrepancy is even larger in galaxy clusters, which need 10 to 100 times more mass. The total needed is more than the su ...
... 16.1 Dark Matter in the Universe • Galaxy mass measurements show that galaxies need between 3 and 10 times more mass than can be observed to explain their rotation curves. • The discrepancy is even larger in galaxy clusters, which need 10 to 100 times more mass. The total needed is more than the su ...
Multiple Scattering in Thick Multifractal Clouds
... reflectance. They clearly showed that i) fractality generally leads to non classical (“anomalous”) thick cloud scaling exponents, ii) the latter were strongly dependent on the type of scaling of the medium, and iii) they are independent of the phase function ([Lovejoy, et al., 1990]). By the 1990’s, ...
... reflectance. They clearly showed that i) fractality generally leads to non classical (“anomalous”) thick cloud scaling exponents, ii) the latter were strongly dependent on the type of scaling of the medium, and iii) they are independent of the phase function ([Lovejoy, et al., 1990]). By the 1990’s, ...
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.