The Earliest Stages of Star and Planet Formation: Core Collapse
... The formation of stars and planets are connected through disks. Our theoretical understanding of disk formation has undergone drastic changes in recent years, and we are on the brink of a revolution in disk observation enabled by ALMA. Large rotationally supported circumstellar disks, although commo ...
... The formation of stars and planets are connected through disks. Our theoretical understanding of disk formation has undergone drastic changes in recent years, and we are on the brink of a revolution in disk observation enabled by ALMA. Large rotationally supported circumstellar disks, although commo ...
Present
... Masses in red stars range from 8x1010 to 6x1011 Mo, if the mean stellar age is below 109 years, and significantly higher masses if the stars are older. They are probably young massive ellipticals in the final stages of star formation, where much of their stellar mass is already in place, yet very ...
... Masses in red stars range from 8x1010 to 6x1011 Mo, if the mean stellar age is below 109 years, and significantly higher masses if the stars are older. They are probably young massive ellipticals in the final stages of star formation, where much of their stellar mass is already in place, yet very ...
Photometric catalog of nearby globular clusters
... In the next subsections, we briefly present the single CMDs and clusters, and give some references to the best existing CMDs. This does not pretend to be a complete bibliographical catalog: a large number of CMDs are available in the literature for many of the clusters of this survey; we will concen ...
... In the next subsections, we briefly present the single CMDs and clusters, and give some references to the best existing CMDs. This does not pretend to be a complete bibliographical catalog: a large number of CMDs are available in the literature for many of the clusters of this survey; we will concen ...
Here - NASA/IPAC Extragalactic Database
... Planetary nebulae (PNe) are evolutionary products of so-called intermediate mass stars (initial masses of 1 – 8 M ) as they progress from the asymptotic giant branch (AGB) to the white dwarf stage. It is the interaction of the slow AGB wind with the fast post-AGB wind which produces the nebula. Bec ...
... Planetary nebulae (PNe) are evolutionary products of so-called intermediate mass stars (initial masses of 1 – 8 M ) as they progress from the asymptotic giant branch (AGB) to the white dwarf stage. It is the interaction of the slow AGB wind with the fast post-AGB wind which produces the nebula. Bec ...
the inclination of the dwarf irregular galaxy
... galaxy (Meurer et al. 2013; Zheng et al. 2013), lending support to the phenomenon of self-regulation by star formation, as suggested by Quirk (1972). However, although the value of the Qg -parameter is approximately constant across a galaxy, it varies from galaxy to galaxy, indicating that the ‘ther ...
... galaxy (Meurer et al. 2013; Zheng et al. 2013), lending support to the phenomenon of self-regulation by star formation, as suggested by Quirk (1972). However, although the value of the Qg -parameter is approximately constant across a galaxy, it varies from galaxy to galaxy, indicating that the ‘ther ...
The X-ray/radio and UV luminosity expected from symbiotic systems
... owing to the existence of the CSM, the possibility of significant blueshifts for some absorption lines can be expected in the spectra of some SNe Ia, even though the true nature of the blueshift is not fully understood (Sternberg et al. 2014). Sternberg et al. (2011) checked the absorption propertie ...
... owing to the existence of the CSM, the possibility of significant blueshifts for some absorption lines can be expected in the spectra of some SNe Ia, even though the true nature of the blueshift is not fully understood (Sternberg et al. 2014). Sternberg et al. (2011) checked the absorption propertie ...
A Herschel/HIFI study of Water in Two Intermediate
... surface of this dense spherical core is still able to radiate energy, allowing the inside to cool and continue to collapse, while matter outside of the core continues to accrete onto the core. The density within the core continues to grow, eventually getting high enough to start nuclear fusion, whic ...
... surface of this dense spherical core is still able to radiate energy, allowing the inside to cool and continue to collapse, while matter outside of the core continues to accrete onto the core. The density within the core continues to grow, eventually getting high enough to start nuclear fusion, whic ...
A new asteroseismic diagnostic for internal rotation in $\ gamma
... branch still remains unexplained by theory. For that reason, we lack knowledge of the inner rotation profile of low-tointermediate mass stars on the main sequence (MS). The work presented here aims to address this. We establish a new method of measuring the core rotation periods of the intermediate- ...
... branch still remains unexplained by theory. For that reason, we lack knowledge of the inner rotation profile of low-tointermediate mass stars on the main sequence (MS). The work presented here aims to address this. We establish a new method of measuring the core rotation periods of the intermediate- ...
MUFASA: The assembly of the red sequence
... its local fluid is less that 0.5, or alternatively if it reaches limits in density of 0.01 times the SF critical density, or a time given by 2% of the Hubble time at launch. We further include feedback from Type Ia supernovae (SNIa) and asymptotic giant branch (AGB) stars, implemented as a delayed c ...
... its local fluid is less that 0.5, or alternatively if it reaches limits in density of 0.01 times the SF critical density, or a time given by 2% of the Hubble time at launch. We further include feedback from Type Ia supernovae (SNIa) and asymptotic giant branch (AGB) stars, implemented as a delayed c ...
on the evolution of anomalous x-ray pulsars and soft gamma
... We show that the period clustering of anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs), their X-ray luminosities, ages, and statistics can be explained with fall back disks with large initial specific angular momentum. The disk evolution models are developed by comparison to self-s ...
... We show that the period clustering of anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs), their X-ray luminosities, ages, and statistics can be explained with fall back disks with large initial specific angular momentum. The disk evolution models are developed by comparison to self-s ...
Oxygen, magnesium and chromium isotopic ratios of
... by Zinner et al. (2003). The seven spinel grains from ordinary chondrites are from a mixed acid-resistant residue of the OCs Semarkona (LL3.0), Bishunpur (LL3.1) and Krymka (LL3.1), prepared using methods similar to those for the Murray residue. These grains ranged in size from 0.3 to 2 m and were ...
... by Zinner et al. (2003). The seven spinel grains from ordinary chondrites are from a mixed acid-resistant residue of the OCs Semarkona (LL3.0), Bishunpur (LL3.1) and Krymka (LL3.1), prepared using methods similar to those for the Murray residue. These grains ranged in size from 0.3 to 2 m and were ...
No Slide Title
... In November, 2001, one of these PMTs imploded and the resulting shockwave caused about 60% of the other PMTs to implode also. The “shock” in the tank was so large that it was recorded on one of Japan’s earthquake ...
... In November, 2001, one of these PMTs imploded and the resulting shockwave caused about 60% of the other PMTs to implode also. The “shock” in the tank was so large that it was recorded on one of Japan’s earthquake ...
Read Claudia`s PhD thesis
... using the Local Group (LG) as a true laboratory. Indeed, the chemistry, kinematics and spatial distribution of stars have unveiled precious informations about the early epochs of the MW formation. Eggen, Lynden-Bell and Sandage (Eggen et al., 1962, hereafter ELS) studying the motion of Galactic high ...
... using the Local Group (LG) as a true laboratory. Indeed, the chemistry, kinematics and spatial distribution of stars have unveiled precious informations about the early epochs of the MW formation. Eggen, Lynden-Bell and Sandage (Eggen et al., 1962, hereafter ELS) studying the motion of Galactic high ...
Polaris B, an optical companion of the Polaris (αUMi) system
... that suggestion (Evans et al. 2007). It would therefore be interesting to establish the atmospheric parameters and chemical composition of component B for comparison with those for the Cepheid Polaris itself – it is known that Cepheid progenitors are main-sequence B stars, more massive and rapidly e ...
... that suggestion (Evans et al. 2007). It would therefore be interesting to establish the atmospheric parameters and chemical composition of component B for comparison with those for the Cepheid Polaris itself – it is known that Cepheid progenitors are main-sequence B stars, more massive and rapidly e ...
Stellar evolution
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.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.