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... outstanding science in a relatively near future. In particular, discovering other worlds like Earth and probing their atmosphere for evidence of life seem within reach with future exo-Earth characterisation nulling interferometry missions. By observing in the mid-infrared (6-20 µm), these space-base ...
... outstanding science in a relatively near future. In particular, discovering other worlds like Earth and probing their atmosphere for evidence of life seem within reach with future exo-Earth characterisation nulling interferometry missions. By observing in the mid-infrared (6-20 µm), these space-base ...
Studies of dark matter in and around stars
... in every day life. The gravitational effects of this dark matter have been observed in many different ways but its true nature is still unknown. In most models, dark matter particles can annihilate with each other into standard model particles; the direct or indirect observation of such annihilation ...
... in every day life. The gravitational effects of this dark matter have been observed in many different ways but its true nature is still unknown. In most models, dark matter particles can annihilate with each other into standard model particles; the direct or indirect observation of such annihilation ...
Environment and self-regulation in galaxy formation
... early-type galaxy population do not confirm this picture. The same colour evolution for both field and cluster galaxies is found in recent redshift surveys (Wolf et al. 2003; Bell et al. 2004; Koo et al. 2005; Tanaka et al. 2005; Bundy et al. 2006). This negligible influence from the environment is ...
... early-type galaxy population do not confirm this picture. The same colour evolution for both field and cluster galaxies is found in recent redshift surveys (Wolf et al. 2003; Bell et al. 2004; Koo et al. 2005; Tanaka et al. 2005; Bundy et al. 2006). This negligible influence from the environment is ...
Star Formation in the Milky Way and Nearby Galaxies Further
... separation have been understandable. The key physical processes that determine how molecular clouds contract and fragment into clumps and cores and finally clusters and individual stars can be probed up close only in the Galaxy, and much of the progress in this subject has come from in-depth case st ...
... separation have been understandable. The key physical processes that determine how molecular clouds contract and fragment into clumps and cores and finally clusters and individual stars can be probed up close only in the Galaxy, and much of the progress in this subject has come from in-depth case st ...
Giant molecular clouds in the dwarf galaxy NGC 1569
... & Filippenko 1996; Gonzalez Delgado et al. 1997), and are believed to be similar to young globular clusters. Age estimates for the SSCs range from 3 to 10 Myr depending upon assumptions about the star formation history. Greggio et al. (1998) have determined from HST WFPC2 images that NGC 1569 has ex ...
... & Filippenko 1996; Gonzalez Delgado et al. 1997), and are believed to be similar to young globular clusters. Age estimates for the SSCs range from 3 to 10 Myr depending upon assumptions about the star formation history. Greggio et al. (1998) have determined from HST WFPC2 images that NGC 1569 has ex ...
Gravitational-wave signal from binary neutron star merger
... gravitational potential, see sec. 3.3) are one possible source of error, which, however, has started to be investigated as such only very recently, looking at the validity of some approximations [92], comparing simulations with initial data computed by different codes [93], or comparing simulations ...
... gravitational potential, see sec. 3.3) are one possible source of error, which, however, has started to be investigated as such only very recently, looking at the validity of some approximations [92], comparing simulations with initial data computed by different codes [93], or comparing simulations ...
galaxy formation and evolution - Yale Astronomy
... 1988, 1992; Caldwell et al. 1992). Here the dependence of Z on L given by these authors has been converted into a dependence on M using the relation between M/L and M given above. If this is done also for the relation between Z and L given by Caldwell et al. (1992) for the giant elliptical galaxies, ...
... 1988, 1992; Caldwell et al. 1992). Here the dependence of Z on L given by these authors has been converted into a dependence on M using the relation between M/L and M given above. If this is done also for the relation between Z and L given by Caldwell et al. (1992) for the giant elliptical galaxies, ...
A Universal Stellar Initial Mass Function? A Critical Look Further
... The logarithmic formalism of the IMF is preferred by some researchers for two reasons: (a) It provides a quick estimate of the relative stellar mass in decadal bins, and (b) it permits description of the IMF as a log-normal function. The log-normal form of the IMF was first introduced by Miller & Sc ...
... The logarithmic formalism of the IMF is preferred by some researchers for two reasons: (a) It provides a quick estimate of the relative stellar mass in decadal bins, and (b) it permits description of the IMF as a log-normal function. The log-normal form of the IMF was first introduced by Miller & Sc ...
Magnetism in Isolated and Binary White Dwarfs
... other than the Sun. If magnetic Ñux was conserved during stellar evolution, white dwarfs should be expected to have magnetic Ðelds of 107È108 G, and the possibility of strongly magnetic white dwarfs was therefore entertained in the literature already in the late 1940s (Blackett 1947) even prior to t ...
... other than the Sun. If magnetic Ñux was conserved during stellar evolution, white dwarfs should be expected to have magnetic Ðelds of 107È108 G, and the possibility of strongly magnetic white dwarfs was therefore entertained in the literature already in the late 1940s (Blackett 1947) even prior to t ...
A spectroscopic study of detached binary systems using precise radial velocities
... this important astrophysical quantity can be estimated in a model-free manner with less than 10% of the orbital cycle observed spectroscopically. Single-lined orbital solutions have been derived for five of the binaries. Two of these systems are astrometric binaries: β Ret and ν Oct. The other SB1 s ...
... this important astrophysical quantity can be estimated in a model-free manner with less than 10% of the orbital cycle observed spectroscopically. Single-lined orbital solutions have been derived for five of the binaries. Two of these systems are astrometric binaries: β Ret and ν Oct. The other SB1 s ...
Dust in Proto-Planetary Disks: Properties and Evolution
... and Beckwith et al. (2000) in Protostars and Planets III and IV summarize what was known at the time. Since Protostars and Planets IV we have seen a lot of progress in our knowledge of grain properties in disks, thanks to highresolution data provided by infrared long-baseline interferometry, the hig ...
... and Beckwith et al. (2000) in Protostars and Planets III and IV summarize what was known at the time. Since Protostars and Planets IV we have seen a lot of progress in our knowledge of grain properties in disks, thanks to highresolution data provided by infrared long-baseline interferometry, the hig ...
3011800000630
... existing then, that any disk in AXP 4U 0142+61 must be truncated at a certain outer radius rout . Now, with the new Spitzer observations of WCK06, the disk is actually detected in the far infrared! We can fit all the data, in optical and infrared bands B, V, R, I, J, H, KS , 4.5 µm and 8 µm (Fig. 1) ...
... existing then, that any disk in AXP 4U 0142+61 must be truncated at a certain outer radius rout . Now, with the new Spitzer observations of WCK06, the disk is actually detected in the far infrared! We can fit all the data, in optical and infrared bands B, V, R, I, J, H, KS , 4.5 µm and 8 µm (Fig. 1) ...
The old Nuclear Star Cluster in the Milky Way
... Effects of dust, rotation and triaxiality on the apparent dynamics of the NSC VH data and VPs in the l direction predicted by the axisymetric model and dust model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Map of AK for the NSC derived from H − K colors. . . . . . . . . . ...
... Effects of dust, rotation and triaxiality on the apparent dynamics of the NSC VH data and VPs in the l direction predicted by the axisymetric model and dust model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Map of AK for the NSC derived from H − K colors. . . . . . . . . . ...
Dust in Proto-Planetary Disks: Properties and Evolution
... is the determination of disk solid masses from millimeter continuum emission, which requires knowledge of the dust absorption coefficient for a specific grain composition and structure, and of the grain temperature. Protoplanetary disks interest us also because they are the place where planets form. ...
... is the determination of disk solid masses from millimeter continuum emission, which requires knowledge of the dust absorption coefficient for a specific grain composition and structure, and of the grain temperature. Protoplanetary disks interest us also because they are the place where planets form. ...
Debris disks: seeing dust, thinking of planetesimals and planets
... mt mp where mt and mp are masses of the p two colliders. Thus two like-sized objects will be destroyed if they collide at a speed exceeding 8Q?D . For two dust grains, the critical speed is several hundred m s−1 . At several tens of AU from a star, this would imply eccentricities of ∼ 0.1 or higher. ...
... mt mp where mt and mp are masses of the p two colliders. Thus two like-sized objects will be destroyed if they collide at a speed exceeding 8Q?D . For two dust grains, the critical speed is several hundred m s−1 . At several tens of AU from a star, this would imply eccentricities of ∼ 0.1 or higher. ...
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.