Unit 5B PowerPoint
... device (copper and iron) thermostat (n.) measures and maintains temperature thermonuclear (adj.): related to fusion, atomic power ...
... device (copper and iron) thermostat (n.) measures and maintains temperature thermonuclear (adj.): related to fusion, atomic power ...
Lecture 2. Thermal evolution and surface emission of neutron stars
... prototypes of a different subpopulation of NSs born with low magnetic field (< few 1011 G) and relatively long spin periods (few tenths of a second). These NSs are relatively hot, and probably not very rare. Surprisingly, we do not see objects of this type in our vicinity. In the solar neighbourhood ...
... prototypes of a different subpopulation of NSs born with low magnetic field (< few 1011 G) and relatively long spin periods (few tenths of a second). These NSs are relatively hot, and probably not very rare. Surprisingly, we do not see objects of this type in our vicinity. In the solar neighbourhood ...
Public outreach: any limit?
... Scope of the survey • Search and counts of all classes of Ha emitting stars/nebulae short-lived but critical (birth, death, binarity, …) stages of stellar evolution: supergiants, LBVs, preMS, WR, Be stars, interacting binaries, PNe, HII regions, SNRs… • Study of Galactic disc structure (stellar p ...
... Scope of the survey • Search and counts of all classes of Ha emitting stars/nebulae short-lived but critical (birth, death, binarity, …) stages of stellar evolution: supergiants, LBVs, preMS, WR, Be stars, interacting binaries, PNe, HII regions, SNRs… • Study of Galactic disc structure (stellar p ...
Document
... passive evolution of stellar populations formed at z>2-3. Slope is primarily driven by mass-metallicity relation. Morphologically (HST)-selected Es and S0s (Bower et al. 1992, Aragon-Salamanca et al. 1993, Rakos et al. 1995, Stanford et al. 1995, 1996, 1997, 1998, Schade et al. 1996, 1997, Ellis et ...
... passive evolution of stellar populations formed at z>2-3. Slope is primarily driven by mass-metallicity relation. Morphologically (HST)-selected Es and S0s (Bower et al. 1992, Aragon-Salamanca et al. 1993, Rakos et al. 1995, Stanford et al. 1995, 1996, 1997, 1998, Schade et al. 1996, 1997, Ellis et ...
The Hidden Lives of Galaxies NSTA 2001
... beyond the visible limits of the galaxy. The temperature of the gas is a measure of its velocity and energy. This gas is so hot (about 10 million degrees Kelvin, or 18 million degrees F), and consequently has such a high velocity, that it first appears to be escaping from the galaxy. Indeed, the amo ...
... beyond the visible limits of the galaxy. The temperature of the gas is a measure of its velocity and energy. This gas is so hot (about 10 million degrees Kelvin, or 18 million degrees F), and consequently has such a high velocity, that it first appears to be escaping from the galaxy. Indeed, the amo ...
Self-similar evolution of wind-blown bubbles with mass
... We also assume that the clumps are stationary with respect to the star, and that they are also cold and dense. Therefore the clumps have neither kinetic or internal energy, and the picked-up mass is thus injected at zero velocity. The stripped mass then acquires momentum and energy from the general ...
... We also assume that the clumps are stationary with respect to the star, and that they are also cold and dense. Therefore the clumps have neither kinetic or internal energy, and the picked-up mass is thus injected at zero velocity. The stripped mass then acquires momentum and energy from the general ...
The Next Great Exoplanet Hunt Please share
... wavelength. In essence, a small signal must be split into even smaller ones, an endeavour only feasible if the signal-to-noise ratio is very high at the outset. And this is only possible for bright stars. The Kepler stars are typically more than a million times fainter than the brightest naked-eye s ...
... wavelength. In essence, a small signal must be split into even smaller ones, an endeavour only feasible if the signal-to-noise ratio is very high at the outset. And this is only possible for bright stars. The Kepler stars are typically more than a million times fainter than the brightest naked-eye s ...
A cold detached dust envelope around an oxygen-rich Mira
... and 100 µm images of R Hya are shown in Fig. 2a and b, respectively. The 60 µm image (Fig. 2a) shows a definite component of the extended emission around R Hya with an effective spatial resolution about 1 arc minute. The extended component is also seen in the 100 µm image (Fig. 2b), though detailed ...
... and 100 µm images of R Hya are shown in Fig. 2a and b, respectively. The 60 µm image (Fig. 2a) shows a definite component of the extended emission around R Hya with an effective spatial resolution about 1 arc minute. The extended component is also seen in the 100 µm image (Fig. 2b), though detailed ...
Detached WD/BD binaries as progenitors of CVs
... Previous searches by e.g. Probst (1983), Zuckerman & Becklin (1987), Green, Ali & Naperwotzki (2000), Farihi, Becklin & Zuckerman (2005), and using 2MASS: Wachter et al. (2003), Wellhouse et al. (2005), Holberg & Magargal (2005), Tremblay & Bergeron (2007) and Hoard et al. (2007) ...
... Previous searches by e.g. Probst (1983), Zuckerman & Becklin (1987), Green, Ali & Naperwotzki (2000), Farihi, Becklin & Zuckerman (2005), and using 2MASS: Wachter et al. (2003), Wellhouse et al. (2005), Holberg & Magargal (2005), Tremblay & Bergeron (2007) and Hoard et al. (2007) ...
Flatfielding chapter for Calibration Volumes
... The following discussion assumes that we can control the telescope well enough to point it to a particular sub-pixel location reliably. If that is not the case, then we should simply command the telescope to move by a pixel or so between each exposure and take whatever random dithering we get. We wi ...
... The following discussion assumes that we can control the telescope well enough to point it to a particular sub-pixel location reliably. If that is not the case, then we should simply command the telescope to move by a pixel or so between each exposure and take whatever random dithering we get. We wi ...
Astronomy Astrophysics NGC 7419 as a template for red supergiant clusters &
... tracks. Though the presence of five red supergiants is marginally consistent with theoretical expectations, the high number of Be stars and very low number of luminous evolved B stars hint at some unknown physical factor that is not considered in current synthesis models. Key words. open clusters an ...
... tracks. Though the presence of five red supergiants is marginally consistent with theoretical expectations, the high number of Be stars and very low number of luminous evolved B stars hint at some unknown physical factor that is not considered in current synthesis models. Key words. open clusters an ...
docx - UT Austin (Astronomy)
... 2) Imagine that you observe a star being orbited by an exoplanet. When you begin observing (Time 1), the exoplanet is in front of the star. A little later (Time 2), the exoplanet has moved so that only a fraction of its surface is in front of the star. At an even later time (Time 3), the exoplanet h ...
... 2) Imagine that you observe a star being orbited by an exoplanet. When you begin observing (Time 1), the exoplanet is in front of the star. A little later (Time 2), the exoplanet has moved so that only a fraction of its surface is in front of the star. At an even later time (Time 3), the exoplanet h ...
Determining the mass loss limit for close
... during evolutionary time scales. The ram pressure of fast CMEs can not be balanced by the ionospheric plasma pressure at orbital distances between 0.02–0.1 AU. Therefore, collisions between hot gas giants and fast CMEs result in large atmospheric mass loss, which may influence the mass evolution of ...
... during evolutionary time scales. The ram pressure of fast CMEs can not be balanced by the ionospheric plasma pressure at orbital distances between 0.02–0.1 AU. Therefore, collisions between hot gas giants and fast CMEs result in large atmospheric mass loss, which may influence the mass evolution of ...
Neutron Star and Superfluidity
... The idea of superfluidity exists inside neutron stars was first proposed by Migdal[1]. In analogy to electrons inside superconductor forming cooper pairs due to electron lattice interaction, it is expected that nucleons in neutron star at sufficiently high density and low temperature can also form coppe ...
... The idea of superfluidity exists inside neutron stars was first proposed by Migdal[1]. In analogy to electrons inside superconductor forming cooper pairs due to electron lattice interaction, it is expected that nucleons in neutron star at sufficiently high density and low temperature can also form coppe ...
Sources of Stellar Energy and the Theory of the Internal Constitution
... inconsistency in the stellar energy problem arises for the reason that the main principles of interaction between matter and radiant energy need to be developed further. Much of the phenomena and empirical correlations discovered by observational astrophysics are linked to the problem of the origin ...
... inconsistency in the stellar energy problem arises for the reason that the main principles of interaction between matter and radiant energy need to be developed further. Much of the phenomena and empirical correlations discovered by observational astrophysics are linked to the problem of the origin ...
Early-type stars in the core of the young open cluster Westerlund 2
... weak metallic lines favours an A0 classification, whilst the width of the Balmer lines suggests a giant luminosity class. We therefore adopt an A0 III spectral type. Our photometric data yield V = 14.13 ± 0.03 and B − V = 0.34 ± 0.04. If the intrinsic colours and absolute magnitudes of MSP 218 are t ...
... weak metallic lines favours an A0 classification, whilst the width of the Balmer lines suggests a giant luminosity class. We therefore adopt an A0 III spectral type. Our photometric data yield V = 14.13 ± 0.03 and B − V = 0.34 ± 0.04. If the intrinsic colours and absolute magnitudes of MSP 218 are t ...
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.