L12 - QUB Astrophysics Research Centre
... There is an upper limit to the mass of a white dwarf - we do not see WDs with masses > 1.4 M We will see in next lectures what the implications of this are for other phenomena in the Universe. It actually led to the discovery of dark energy! The collapse of massive stars produces two types of remna ...
... There is an upper limit to the mass of a white dwarf - we do not see WDs with masses > 1.4 M We will see in next lectures what the implications of this are for other phenomena in the Universe. It actually led to the discovery of dark energy! The collapse of massive stars produces two types of remna ...
HR Diagram, Star Clusters, and Stellar Evolution
... are called long-period variables. • The envelope material ejected by the star forms an expanding shell of gas that is known as a planetary nebula (PN) ...
... are called long-period variables. • The envelope material ejected by the star forms an expanding shell of gas that is known as a planetary nebula (PN) ...
Black Holes
... Black Holes are strange regions where gravity is strong enough to bend light, warp space and distort time. (Space) They are the cold remnants of former stars, so dense that no matter (not even light) can escape their gravitational pull. (National Geographic) A black hole is not really a “hole.” It ...
... Black Holes are strange regions where gravity is strong enough to bend light, warp space and distort time. (Space) They are the cold remnants of former stars, so dense that no matter (not even light) can escape their gravitational pull. (National Geographic) A black hole is not really a “hole.” It ...
ppt - ciera
... Chandra and XMM fields reveals no new 530 s pulsars, so there is a <0.5% chance of finding a magnetar in any field (Nechita, Gaensler, Muno, et al. in prep). • The pulsar is well within the cluster, with a <10% chance of being an unrelated X-ray source. ...
... Chandra and XMM fields reveals no new 530 s pulsars, so there is a <0.5% chance of finding a magnetar in any field (Nechita, Gaensler, Muno, et al. in prep). • The pulsar is well within the cluster, with a <10% chance of being an unrelated X-ray source. ...
Document
... Blazars at very high energies Bazars are powerful gamma-ray sources. The most powerful of them have equivalent isotropic luminosity 1049 erg/s. Collimation θ2/2 ~ 10-2 – 10-3. θ – jet opening angle. EGRET detected 66 (+27) sources of this type. New breakthrough is expected after the launch of GLAST ...
... Blazars at very high energies Bazars are powerful gamma-ray sources. The most powerful of them have equivalent isotropic luminosity 1049 erg/s. Collimation θ2/2 ~ 10-2 – 10-3. θ – jet opening angle. EGRET detected 66 (+27) sources of this type. New breakthrough is expected after the launch of GLAST ...
Low mass star formation
... Turbulence-driven? (consistent with width) Magnetic fields? No velocity or polarisation measurements... Relation to SF? (occurs along filaments & at junctures) ...
... Turbulence-driven? (consistent with width) Magnetic fields? No velocity or polarisation measurements... Relation to SF? (occurs along filaments & at junctures) ...
poster
... Most models of jet launching rely on a magnetic field in either the central source, the accretion disk or both. However, the well-studied nearby young Herbig Ae star HD 163296 has a measured weak stellar magnetic field (main-sequence A stars do not have magnetic fields at all), and even indications ...
... Most models of jet launching rely on a magnetic field in either the central source, the accretion disk or both. However, the well-studied nearby young Herbig Ae star HD 163296 has a measured weak stellar magnetic field (main-sequence A stars do not have magnetic fields at all), and even indications ...
L2 Star formation Part I
... Star formation takes place in cold, dense gas clouds: The molecular clouds. Stars form in groups or clusters. The largest GMC in Orion is about 1000 light years away. Hot young stars (25-50 million year old) ionize their surroundings and are therefore easily visible. ...
... Star formation takes place in cold, dense gas clouds: The molecular clouds. Stars form in groups or clusters. The largest GMC in Orion is about 1000 light years away. Hot young stars (25-50 million year old) ionize their surroundings and are therefore easily visible. ...
File
... light squared being a constant you could have different outputs based on the mass. For example the force of an atom has a lot of energy, while not accessible all the time, this small amount of mass has high energy. The equation E = mc2 comes from the relativistic energy/momentum equation in Albert E ...
... light squared being a constant you could have different outputs based on the mass. For example the force of an atom has a lot of energy, while not accessible all the time, this small amount of mass has high energy. The equation E = mc2 comes from the relativistic energy/momentum equation in Albert E ...
Astronomy Exam #2 for the 10
... The two neutrinos are sub-atomic particles with almost no mass that travel near light-speed and only weakly interact with matter. They are created with the two neutrons as a by-product of the fusion of hydrogen into helium. The gamma rays are very high energy photons with no mass and travel at light ...
... The two neutrinos are sub-atomic particles with almost no mass that travel near light-speed and only weakly interact with matter. They are created with the two neutrons as a by-product of the fusion of hydrogen into helium. The gamma rays are very high energy photons with no mass and travel at light ...
Apparent magnitude
... Dust hides the centre that could otherwise be seen as a bright ”cloud” in the southern sky (optical extinction 28 mag) X-ray observations (for example, hot gas, x-ray binaries, ...
... Dust hides the centre that could otherwise be seen as a bright ”cloud” in the southern sky (optical extinction 28 mag) X-ray observations (for example, hot gas, x-ray binaries, ...
Gamma Ray Bursts: The biggest bang since the big one!
... • Can get in closer to spinning black hole. More energy to dissipate over smaller area: disc ...
... • Can get in closer to spinning black hole. More energy to dissipate over smaller area: disc ...
Nuclear Synthesis
... • Black holes can keep accumulating mass…including “colliding” Black holes. Very massive (million times mass Sun) at center of many galaxies ...
... • Black holes can keep accumulating mass…including “colliding” Black holes. Very massive (million times mass Sun) at center of many galaxies ...
Gravitational redshifts
... … where starlight and stellar spectra originate Simulations feasible for widely different stars ...
... … where starlight and stellar spectra originate Simulations feasible for widely different stars ...
The supernova of AD1181 – an update
... (1982) from neutral hydrogen (21 cm) line observations – has been confirmed by more recent 21 cm observations by Roberts et al. (1993). These authors also confirmed that confusion with structure in hydrogen emission was responsible for apparent absorption features that had led to the erroneous large ...
... (1982) from neutral hydrogen (21 cm) line observations – has been confirmed by more recent 21 cm observations by Roberts et al. (1993). These authors also confirmed that confusion with structure in hydrogen emission was responsible for apparent absorption features that had led to the erroneous large ...
2017 MIT Invitational
... 13. A star with the same absolute magnitude of the Sun has a parallax of 0.01”. The H-α line of this star is measured to be 6565.8 Angstroms. The H-α wavelength is expected to be at 6562.8 Angstroms based on laboratory measurements. (a) What is the distance to this star, in parsecs? (b) What is the ...
... 13. A star with the same absolute magnitude of the Sun has a parallax of 0.01”. The H-α line of this star is measured to be 6565.8 Angstroms. The H-α wavelength is expected to be at 6562.8 Angstroms based on laboratory measurements. (a) What is the distance to this star, in parsecs? (b) What is the ...
Traps in Space-Time - Max-Planck
... at the centers of galaxies. They may possibly have formed from the first generation of extremely heavy stars that, having become a black hole, rapidly accreted more and more mass and thus more and more angular momentum. ...
... at the centers of galaxies. They may possibly have formed from the first generation of extremely heavy stars that, having become a black hole, rapidly accreted more and more mass and thus more and more angular momentum. ...
Galaxies – Island universes
... Galaxy Formation Summary • Galaxies form from collisions of proto-galactic clumps in the first billion years or so after the Big Bang • Many have later infalling matter which has been pulled on by nearby mass and thus doesn’t fall straight in. It settles into a rotating disk, arranging itself into ...
... Galaxy Formation Summary • Galaxies form from collisions of proto-galactic clumps in the first billion years or so after the Big Bang • Many have later infalling matter which has been pulled on by nearby mass and thus doesn’t fall straight in. It settles into a rotating disk, arranging itself into ...
Lab 2
... In this lab, you will be asked to take spectra with the 24” SBO spectrograph. The goal is to obtain descent high signal-to-noise spectra of stars having a variety of properties. One of the stars, Vega, will be used for “spectral flat-fielding” the other spectra. The data resulting from this exercise ...
... In this lab, you will be asked to take spectra with the 24” SBO spectrograph. The goal is to obtain descent high signal-to-noise spectra of stars having a variety of properties. One of the stars, Vega, will be used for “spectral flat-fielding” the other spectra. The data resulting from this exercise ...
Exercises
... i-iii. Answer question (a) iii, iv and v for the dynamical timescale. iv. In stellar evolution models one often assumes that stars evolve quasi-statically, i.e. that the star remains in hydrostatic equilibrium throughout. Why can we make this assumption? v. Rapid changes that are sometimes observed ...
... i-iii. Answer question (a) iii, iv and v for the dynamical timescale. iv. In stellar evolution models one often assumes that stars evolve quasi-statically, i.e. that the star remains in hydrostatic equilibrium throughout. Why can we make this assumption? v. Rapid changes that are sometimes observed ...
Chapter 13 The Stellar Graveyard
... By following the fate of a tiny proton whipping about at near light speed close to the neutron star with NASA's Rossi X-ray Explorer satellite, scientists calculated this star's magnetic field to be up to 10 times more powerful than previously thought -- with a force strong enough to slow a steel lo ...
... By following the fate of a tiny proton whipping about at near light speed close to the neutron star with NASA's Rossi X-ray Explorer satellite, scientists calculated this star's magnetic field to be up to 10 times more powerful than previously thought -- with a force strong enough to slow a steel lo ...
Supernovae March 23 − Supernova 1987A
... Degeneracy pressure prevents temperature from rising. Carbon burning. That is wrong; the sun will become a supernova. ...
... Degeneracy pressure prevents temperature from rising. Carbon burning. That is wrong; the sun will become a supernova. ...
Cygnus X-1
Cygnus X-1 (abbreviated Cyg X-1) is a well-known galactic X-ray source, thought to be a black hole, in the constellation Cygnus. It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources seen from Earth, producing a peak X-ray flux density of 6977229999999999999♠2.3×10−23 Wm−2 Hz−1 (7003230000000000000♠2.3×103 Jansky). Cygnus X-1 was the first X-ray source widely accepted to be a black hole and it remains among the most studied astronomical objects in its class. The compact object is now estimated to have a mass about 14.8 times the mass of the Sun and has been shown to be too small to be any known kind of normal star, or other likely object besides a black hole. If so, the radius of its event horizon is about 7004440000000000000♠44 km.Cygnus X-1 belongs to a high-mass X-ray binary system about 7019574266339685654♠6070 ly from the Sun that includes a blue supergiant variable star designated HDE 226868 which it orbits at about 0.2 AU, or 20% of the distance from the Earth to the Sun. A stellar wind from the star provides material for an accretion disk around the X-ray source. Matter in the inner disk is heated to millions of degrees, generating the observed X-rays. A pair of jets, arranged perpendicular to the disk, are carrying part of the energy of the infalling material away into interstellar space.This system may belong to a stellar association called Cygnus OB3, which would mean that Cygnus X-1 is about five million years old and formed from a progenitor star that had more than 7001400000000000000♠40 solar masses. The majority of the star's mass was shed, most likely as a stellar wind. If this star had then exploded as a supernova, the resulting force would most likely have ejected the remnant from the system. Hence the star may have instead collapsed directly into a black hole.Cygnus X-1 was the subject of a friendly scientific wager between physicists Stephen Hawking and Kip Thorne in 1975, with Hawking betting that it was not a black hole. He conceded the bet in 1990 after observational data had strengthened the case that there was indeed a black hole in the system. This hypothesis has not been confirmed due to a lack of direct observation but has generally been accepted from indirect evidence.