The Green Valley is a Red Herring: Galaxy Zoo reveals two
... 2011; Lee et al. 2012; Leitner 2012)). Most star-forming galaxies live on the main sequence, so tracing the populations leaving the main sequence – those with lower sSFRs – probes the quenching mechanism(s) and, as Peng et al. (2010) showed, there may be at least two very different quenching process ...
... 2011; Lee et al. 2012; Leitner 2012)). Most star-forming galaxies live on the main sequence, so tracing the populations leaving the main sequence – those with lower sSFRs – probes the quenching mechanism(s) and, as Peng et al. (2010) showed, there may be at least two very different quenching process ...
Galaxies in the Universe: An Introduction, Second Edition
... We have tried to place material which is relatively more difficult or more intricate at the end of each subsection. Students who find some portions heavy going at a first reading are advised to move to the following subsection and return later to the troublesome passage. Some problems have been include ...
... We have tried to place material which is relatively more difficult or more intricate at the end of each subsection. Students who find some portions heavy going at a first reading are advised to move to the following subsection and return later to the troublesome passage. Some problems have been include ...
A numerical study of recent tidal interactions between dwarf galaxies
... has an influence on the evolution of the dwarf galaxies. In all studies tidal stripping and tidal tails were observed. These interactions also led to star formation bursts in the dwarf galaxies. And there was stated by Mayer et al. (2001a) that dwarf galaxies in the Milky Way potential were transfor ...
... has an influence on the evolution of the dwarf galaxies. In all studies tidal stripping and tidal tails were observed. These interactions also led to star formation bursts in the dwarf galaxies. And there was stated by Mayer et al. (2001a) that dwarf galaxies in the Milky Way potential were transfor ...
Massive Disruptions in the Cool Core of MACS J1931.8-2634 Steven Ehlert
... Uncertainty in cavity volume puts uncertainty of 4PV & jet power at a factor of ~2-3. ...
... Uncertainty in cavity volume puts uncertainty of 4PV & jet power at a factor of ~2-3. ...
Giant Molecular Clouds in Local Group Galaxies
... is a good value to use in most galaxies (except the SMC) if the GMCs are virialized. However, if the clouds are only marginally self-gravitating, as appears to be the case judging from their appearance, half the virial value may be more appropriate. There is no clear trend of XCO with metallicity. T ...
... is a good value to use in most galaxies (except the SMC) if the GMCs are virialized. However, if the clouds are only marginally self-gravitating, as appears to be the case judging from their appearance, half the virial value may be more appropriate. There is no clear trend of XCO with metallicity. T ...
From Filamentary Networks to Dense Cores in Molecular Clouds
... connection between filament structure and the formation of cold dense cores. Filament intersections can provide higher column densities at the location of intersection, enhancing star formation even further. Indeed, localized mass accumulation due to filament mergers may provide the conditions neces ...
... connection between filament structure and the formation of cold dense cores. Filament intersections can provide higher column densities at the location of intersection, enhancing star formation even further. Indeed, localized mass accumulation due to filament mergers may provide the conditions neces ...
Small glitches: the role of strange nuggets?
... be studied in some detail, but unfortunately even numerical simulations in the framework of conventional microscopic dark matter particles have not reached a consensus about the cosmic structure formation (e.g. see Gao & Theuns (2007)). Similar macroscopic dark matter candidates are the so called ma ...
... be studied in some detail, but unfortunately even numerical simulations in the framework of conventional microscopic dark matter particles have not reached a consensus about the cosmic structure formation (e.g. see Gao & Theuns (2007)). Similar macroscopic dark matter candidates are the so called ma ...
Neutron Stars and the Determination of the Dense Matter Equation
... A physical understanding of the behaviour of cold ultra-dense matter – at and above nuclear density – can only be achieved by the study of neutron stars. The surface thermal emission from neutron stars in quiescent low-mass X-ray binaries (qLMXBs) inside globular clusters has proven useful for that ...
... A physical understanding of the behaviour of cold ultra-dense matter – at and above nuclear density – can only be achieved by the study of neutron stars. The surface thermal emission from neutron stars in quiescent low-mass X-ray binaries (qLMXBs) inside globular clusters has proven useful for that ...
Post-starburst galaxies: more than just an interesting curiosity
... 1997; Noeske et al. 2007; Tresse et al. 2007). However, the process, or processes, responsible for this gradual decline remain to be determined. What physical mechanisms cause a galaxy to stop forming stars, to turn into a spheroid, and thus to enter the red sequence? There are many competing theori ...
... 1997; Noeske et al. 2007; Tresse et al. 2007). However, the process, or processes, responsible for this gradual decline remain to be determined. What physical mechanisms cause a galaxy to stop forming stars, to turn into a spheroid, and thus to enter the red sequence? There are many competing theori ...
The Mass of Quasars Yue Shen
... the Salpeter time or e-folding time. If quasars do not radiate beyond the Eddington limit λ = 1, the observed luminosity provides a lower-limit on their BH mass (e.g., Zel’dovich & Novikov 1964). The discovery of luminous quasars (with Lbol & 1047 erg s−1) at z > 6 (e.g., Fan et al. 2001; Mortlock e ...
... the Salpeter time or e-folding time. If quasars do not radiate beyond the Eddington limit λ = 1, the observed luminosity provides a lower-limit on their BH mass (e.g., Zel’dovich & Novikov 1964). The discovery of luminous quasars (with Lbol & 1047 erg s−1) at z > 6 (e.g., Fan et al. 2001; Mortlock e ...
elt science case
... The prospects for the use of GRBs as standard candles clearly depend on the increase of the number of detected GRBs which satisfy the Epeak-E correlation. Many events are required to test and fully calibrate this correlation. Clearly the extension of the sample in the coming years will also extend ...
... The prospects for the use of GRBs as standard candles clearly depend on the increase of the number of detected GRBs which satisfy the Epeak-E correlation. Many events are required to test and fully calibrate this correlation. Clearly the extension of the sample in the coming years will also extend ...
The age of elliptical galaxies and bulges in a merger model The age
... would require a very precise synchronization of formation epochs and star formation histories for these galaxies. Likewise, Bender, Burstein & Faber (1993) find a very tight relationship between the strength of the Mg II index at the centre of ellipticals and their central velocity dispersions, (1. ...
... would require a very precise synchronization of formation epochs and star formation histories for these galaxies. Likewise, Bender, Burstein & Faber (1993) find a very tight relationship between the strength of the Mg II index at the centre of ellipticals and their central velocity dispersions, (1. ...
The Star Cluster Population of M51: II. Age distribution and relations
... to study extragalactic star clusters. This is due to its relatively close distance of ∼ 8.4 Mpc (Feldmeier et al. 1997) and its almost face-on orientation. Physically it is an interesting case study because it seems to have had a strong interaction with its companion, NGC 5195 an S0 peculiar galaxy, ...
... to study extragalactic star clusters. This is due to its relatively close distance of ∼ 8.4 Mpc (Feldmeier et al. 1997) and its almost face-on orientation. Physically it is an interesting case study because it seems to have had a strong interaction with its companion, NGC 5195 an S0 peculiar galaxy, ...
The galaxy stellar mass function at 3.5 ≤z ≤ 7.5 in the CANDELS
... Subsequently, Santini et al. (2012a) proposed that a steepening of the GSMF with increasing redshift might remove any discrepancy at 2 < z < 4, but at z < 2 found that the steepening was insufficient to bridge the apparent gap. More recently still, Behroozi et al. (2013) pointed out that the previous ...
... Subsequently, Santini et al. (2012a) proposed that a steepening of the GSMF with increasing redshift might remove any discrepancy at 2 < z < 4, but at z < 2 found that the steepening was insufficient to bridge the apparent gap. More recently still, Behroozi et al. (2013) pointed out that the previous ...
First Results from the WISE Enhanced Resolution Galaxy Atlas
... plexity and sustainability of converting gas into stars. Comprising the local universe, nearby galaxies represent a fossil record of galaxy evolution, the boundary condition for cosmological models that explain past and current state of the universe. Although galaxies come in all shapes, sizes, mass ...
... plexity and sustainability of converting gas into stars. Comprising the local universe, nearby galaxies represent a fossil record of galaxy evolution, the boundary condition for cosmological models that explain past and current state of the universe. Although galaxies come in all shapes, sizes, mass ...
THE RED-SEQUENCE LUMINOSITY FUNCTION IN GALAXY
... faint red-sequence galaxies relative to local clusters has been claimed, in accordance with this picture (De Lucia et al. 2004, 2007; Tanaka et al. 2005). However, all of these high-redshift works have found a large cluster-to-cluster scatter in their samples of sizes of approximately 1Y10 clusters, ...
... faint red-sequence galaxies relative to local clusters has been claimed, in accordance with this picture (De Lucia et al. 2004, 2007; Tanaka et al. 2005). However, all of these high-redshift works have found a large cluster-to-cluster scatter in their samples of sizes of approximately 1Y10 clusters, ...
Abstract Title of Dissertation: BLACK HOLE DYNAMICS AND GRAVITATIONAL RADIATION IN GALACTIC NUCLEI
... that host supermassive black holes. Mergers between stellar-mass black holes will be key sources of gravitational radiation for ground-based detectors. However, the rates of these events are highly uncertain, because we can not observe these binaries electromagnetically. In this work, we show that t ...
... that host supermassive black holes. Mergers between stellar-mass black holes will be key sources of gravitational radiation for ground-based detectors. However, the rates of these events are highly uncertain, because we can not observe these binaries electromagnetically. In this work, we show that t ...
Research Report for 2015/2016
... Rochester, Imperial College, and AWE to study shock waves in collimated jets using highpowered lasers. Funded by the DOE, one project uses the Omega laser to launch jets and observe what happens when strong shock waves intersect. A separate project explores what happens to shock waves in a plasma wh ...
... Rochester, Imperial College, and AWE to study shock waves in collimated jets using highpowered lasers. Funded by the DOE, one project uses the Omega laser to launch jets and observe what happens when strong shock waves intersect. A separate project explores what happens to shock waves in a plasma wh ...
Annual Report 2014 - Max Planck Institute for Astrophysics
... the directorship of Ludwig Biermann. It was estab- MPA has had an internationally-recognized numerlished as an offshoot of the Max-Planck-Institut für ical astrophysics program that was long unparalPhysik, which at that time had just moved from leled by any other institution of similar size. Göttinge ...
... the directorship of Ludwig Biermann. It was estab- MPA has had an internationally-recognized numerlished as an offshoot of the Max-Planck-Institut für ical astrophysics program that was long unparalPhysik, which at that time had just moved from leled by any other institution of similar size. Göttinge ...
X-ray binaries in the Milky Way and other galaxies
... 6.1. Universal HMXB Luminosity Function ? . . . . . . . . . . . . . . . . . . . 6.2. High Luminosity cut-off . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3. Total X-ray luminosity as SFR indicator . . . . . . . . . . . . . . . . . . . 6.4. Theoretical LX –SFR relation . . . . . . . . . ...
... 6.1. Universal HMXB Luminosity Function ? . . . . . . . . . . . . . . . . . . . 6.2. High Luminosity cut-off . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3. Total X-ray luminosity as SFR indicator . . . . . . . . . . . . . . . . . . . 6.4. Theoretical LX –SFR relation . . . . . . . . . ...
arXiv:1410.8731v2 [astro
... We analyse and report in detail new near-infrared (1.45 - 2.45 microns) observations of the Dusty S-cluster Object (DSO/G2) during its approach to the black hole at the center of the Galaxy that were carried out with ESO VLT/SINFONI between February and September 2014. Before May 2014 we detect spat ...
... We analyse and report in detail new near-infrared (1.45 - 2.45 microns) observations of the Dusty S-cluster Object (DSO/G2) during its approach to the black hole at the center of the Galaxy that were carried out with ESO VLT/SINFONI between February and September 2014. Before May 2014 we detect spat ...
DEDUCING THE LIFETIME OF SHORT GAMMA
... they are on average more massive and thus make a larger contribution to the local stellar mass density. The total stellar mass from early-type galaxies is about 1.3 (2.3) times that from late-type galaxies, if the classification of galaxy types is based on light concentration (color). If early- and ...
... they are on average more massive and thus make a larger contribution to the local stellar mass density. The total stellar mass from early-type galaxies is about 1.3 (2.3) times that from late-type galaxies, if the classification of galaxy types is based on light concentration (color). If early- and ...
Radiation-driven wind models of massive stars
... In the early universe, when primordial elements left over from the Big Bang were the only constituents of the cosmos, Nature may have operated in the opposite way, and massive stars may have preferentially been formed over low mass stars (e.g. Carr et al. 1984, Larson 1998). Some of these arguments ...
... In the early universe, when primordial elements left over from the Big Bang were the only constituents of the cosmos, Nature may have operated in the opposite way, and massive stars may have preferentially been formed over low mass stars (e.g. Carr et al. 1984, Larson 1998). Some of these arguments ...
Flux Calibration of the ACS CCD Cameras SPACE TELESCOPE SCIENCE
... data but do encompass the adopted value of 0.943 from Table 1. The S05 data without overscan are of lower fidelity but do suggest that any variation of the EE correction around the field of view is less than 1% for photometry with large radii on the order of one arcsec. Red stars of spectral type M ...
... data but do encompass the adopted value of 0.943 from Table 1. The S05 data without overscan are of lower fidelity but do suggest that any variation of the EE correction around the field of view is less than 1% for photometry with large radii on the order of one arcsec. Red stars of spectral type M ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.