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... These sources can contribute both to the population of unidentified point-like sources and to the local cosmic-ray electron spectrum. The inverse Compton emission of these locally generated cosmic rays may explain the variety of gamma-ray spectra detected from nearby molecular clouds. ...
... These sources can contribute both to the population of unidentified point-like sources and to the local cosmic-ray electron spectrum. The inverse Compton emission of these locally generated cosmic rays may explain the variety of gamma-ray spectra detected from nearby molecular clouds. ...
Lecture 2. Thermal evolution and surface emission of - X-Ray
... Envelopes can be related to the fact that we see a subpopulation of hot NS Thick lines – non-magnetic in CCOs with relatively long initial spin periods and low magnetic field, but do not observed representatives of this population around us, i.e. in the Solar vicinity. Solid line M=1.3 Msolar, Dashe ...
... Envelopes can be related to the fact that we see a subpopulation of hot NS Thick lines – non-magnetic in CCOs with relatively long initial spin periods and low magnetic field, but do not observed representatives of this population around us, i.e. in the Solar vicinity. Solid line M=1.3 Msolar, Dashe ...
Photoelectric Photometry of the Pleiades
... The computer program you will use is a realistic simulation of a UBV photometer attached to a moderate sized research telescope. The telescope is controlled by a computer that allows you to move from star to star and make measurements. Different filters can be selected for each observation, and the ...
... The computer program you will use is a realistic simulation of a UBV photometer attached to a moderate sized research telescope. The telescope is controlled by a computer that allows you to move from star to star and make measurements. Different filters can be selected for each observation, and the ...
HS 0702+6043: a star showing both short-period p
... Context. The hot subdwarf B star HS 0702+6043 is known as a large-amplitude, short-period p-mode pulsator of the EC 14026 type. Its atmospheric parameters place it at the common boundary between the empirical instability regions of the EC 14026 variables and the typically cooler long-period g-mode p ...
... Context. The hot subdwarf B star HS 0702+6043 is known as a large-amplitude, short-period p-mode pulsator of the EC 14026 type. Its atmospheric parameters place it at the common boundary between the empirical instability regions of the EC 14026 variables and the typically cooler long-period g-mode p ...
L133 VERY LARGE TELESCOPE SPECTRA OF CARBON STARS
... In general, stars are oxygen-rich when they enter the AGB phase. Third dredge-up leads to 12C enrichment in the atmospheres of AGB stars. If the C/O ratio exceeds unity after the third dredge-up, the star is classified as a carbon star. Theoretical models have predicted that the amount of 12C enrich ...
... In general, stars are oxygen-rich when they enter the AGB phase. Third dredge-up leads to 12C enrichment in the atmospheres of AGB stars. If the C/O ratio exceeds unity after the third dredge-up, the star is classified as a carbon star. Theoretical models have predicted that the amount of 12C enrich ...
Stars, Galaxies, and the Universe
... holes. Here, a black hole is shown pulling matter from a companion star. ...
... holes. Here, a black hole is shown pulling matter from a companion star. ...
description
... Probably not. The stars within one constellation are all at different distances from us, on Earth. It’s only by chance, that they appear to be next to each other, to form a shape or constellation. Ask the students to go out at night in a couple of months and record their observations about the same ...
... Probably not. The stars within one constellation are all at different distances from us, on Earth. It’s only by chance, that they appear to be next to each other, to form a shape or constellation. Ask the students to go out at night in a couple of months and record their observations about the same ...
Transiting exoplanets from the CoRoT space mission
... Since the beginning of 2007, the space mission CoRoT performs wide-field stellar photometry at ultra-high precision from space (Rouan et al. 1998; Baglin et al. 2006). Currently, during an observing run up to 6,000 stars1 can be monitored simultaneously and continuously over periods of 20 to 150 day ...
... Since the beginning of 2007, the space mission CoRoT performs wide-field stellar photometry at ultra-high precision from space (Rouan et al. 1998; Baglin et al. 2006). Currently, during an observing run up to 6,000 stars1 can be monitored simultaneously and continuously over periods of 20 to 150 day ...
Current Challenges Facing Planet Transit Surveys
... Although there may be a few more transiting planets in the current radial velocity sample, the ongoing Doppler surveys will not provide a substantial population of such objects. The primary goal of these surveys is to characterize the planet population at large semi-major axes. As a result, these su ...
... Although there may be a few more transiting planets in the current radial velocity sample, the ongoing Doppler surveys will not provide a substantial population of such objects. The primary goal of these surveys is to characterize the planet population at large semi-major axes. As a result, these su ...
arXiv:1502.04693v1 [gr
... et al. 2014a). Three objects, WD 0806−661(Luhman et al. 2011), CFBDSIR J1458+1013B (Liu et al. 2011), and WISE 0855−0714 (Luhman 2014), likely have effective temperatures similar to (or less than) the above Y dwarfs, but have yet to be spectroscopically confirmed. Ground-based follow-up observations ...
... et al. 2014a). Three objects, WD 0806−661(Luhman et al. 2011), CFBDSIR J1458+1013B (Liu et al. 2011), and WISE 0855−0714 (Luhman 2014), likely have effective temperatures similar to (or less than) the above Y dwarfs, but have yet to be spectroscopically confirmed. Ground-based follow-up observations ...
Non-Thermal Radio Emission from Binary Systems
... 5 GHz with a radio telescope with a typical minimum flux density of 1 mJy: the quiet Sun: the slowly varying component: the very strong solar radio bursts: ...
... 5 GHz with a radio telescope with a typical minimum flux density of 1 mJy: the quiet Sun: the slowly varying component: the very strong solar radio bursts: ...
11 The Interstellar Medium
... Globular clusters orbit the center of the Milky Way, and are usually seen above or below the galactic plane far from our Sun. Copyright © 2010 Pearson Education, Inc. ...
... Globular clusters orbit the center of the Milky Way, and are usually seen above or below the galactic plane far from our Sun. Copyright © 2010 Pearson Education, Inc. ...
RHIC - HIM
... in collaboration with F. Zantow (Bielefeld Group) Still on-going, but we are finding similar results ...
... in collaboration with F. Zantow (Bielefeld Group) Still on-going, but we are finding similar results ...
Terzan 5`s Pulsars Fastest
... o Ter5ad is a 716-Hz/1.396-ms eclipsing binary radio pulsar in the rich, dense globular cluster Terzan 5. It is in a highly circular 1.1-day orbit with a > 0.14 Msun companion. o The fast rotation of Ter5ad constrains its radius to be < 16 km, assuming its mass is less than 2 Msun (Fig 1). o The spi ...
... o Ter5ad is a 716-Hz/1.396-ms eclipsing binary radio pulsar in the rich, dense globular cluster Terzan 5. It is in a highly circular 1.1-day orbit with a > 0.14 Msun companion. o The fast rotation of Ter5ad constrains its radius to be < 16 km, assuming its mass is less than 2 Msun (Fig 1). o The spi ...
File - Astronomy Home
... live in the Northern Hemisphere. If you are below the Equator, look for Pegasus in late winter and through spring. When looking at the image, it is difficult to see the figure as a horse. That is because the constellation is actually upsidedown! Imagine it flipped over, and you can see what could be ...
... live in the Northern Hemisphere. If you are below the Equator, look for Pegasus in late winter and through spring. When looking at the image, it is difficult to see the figure as a horse. That is because the constellation is actually upsidedown! Imagine it flipped over, and you can see what could be ...
Lecture 2
... age (time t) and chemical composition (X, Y, Z). Composition parameterized with the notation: X = mass fraction of hydrogen H Y = mass fraction of helium He Z = mass fraction of all other elements e.g., for the Sun: X¤ = 0.747 ; Y¤ = 0.236 ; Z¤ = 0.017 Note: Z is often referred to as metallicity We ...
... age (time t) and chemical composition (X, Y, Z). Composition parameterized with the notation: X = mass fraction of hydrogen H Y = mass fraction of helium He Z = mass fraction of all other elements e.g., for the Sun: X¤ = 0.747 ; Y¤ = 0.236 ; Z¤ = 0.017 Note: Z is often referred to as metallicity We ...
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.