The cosmic origin of fluorine and sulphur
... Practically only the two lightest elements, hydrogen and helium, were formed during the Big Bang when our Universe was born. All other elements have been formed, and keep being formed, in different processes in different types of stars. is means that all atoms, except hydrogen and helium, that build ...
... Practically only the two lightest elements, hydrogen and helium, were formed during the Big Bang when our Universe was born. All other elements have been formed, and keep being formed, in different processes in different types of stars. is means that all atoms, except hydrogen and helium, that build ...
Option D – Astrophysics
... a star and it is very similar to billions of other stars in the universe. It has many objects orbiting around it that are held in their orbits by gravity. The solar system is an example of a planetary system. Most of the planets have one or more objects orbiting around them. These are called moons. ...
... a star and it is very similar to billions of other stars in the universe. It has many objects orbiting around it that are held in their orbits by gravity. The solar system is an example of a planetary system. Most of the planets have one or more objects orbiting around them. These are called moons. ...
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 ...
The star formation histories of two northern LMC fields
... the star formation rate in these fields, beginning approximately 2.5 Gyr ago, with the current metallicity in the region being Fe=H 20:38 ^ 0:10: The two fields have had very similar star formation rates until 200 Myr ago, at which point one shows a large increase. Key words: Magellanic Clouds ± ...
... the star formation rate in these fields, beginning approximately 2.5 Gyr ago, with the current metallicity in the region being Fe=H 20:38 ^ 0:10: The two fields have had very similar star formation rates until 200 Myr ago, at which point one shows a large increase. Key words: Magellanic Clouds ± ...
Isotopic composition of Hg and Pt in 5 slowly rotating HgMn stars *
... 1:67 for the ratio of the radii of the primary to the secondary stars, and Te = 9200 K, log g = 4:2, a microturbulent velocity = 2:0 km s;1 , and v sin i = 2 km s;1 for the secondary. Furthermore, we assumed solar chemical composition for this star, in spite of the fact that Wahlgren at al. (1994 ...
... 1:67 for the ratio of the radii of the primary to the secondary stars, and Te = 9200 K, log g = 4:2, a microturbulent velocity = 2:0 km s;1 , and v sin i = 2 km s;1 for the secondary. Furthermore, we assumed solar chemical composition for this star, in spite of the fact that Wahlgren at al. (1994 ...
Submillimeter Array 12CO (2-1) Imaging of the NGC
... 2.3. CO-to-H2 Conversion Factor and Mass of GMCs Observations have revealed discrepancies regarding the CO-toH2 conversion factor XCO in NGC 6946. Donovan Meyer et al. (2012) derived an XCO similar to the Milky Way (MW) value (4.4 M☉pc−2 (K km s−1)−1; Sandstrom et al. 2013) by assuming that GMCs we ...
... 2.3. CO-to-H2 Conversion Factor and Mass of GMCs Observations have revealed discrepancies regarding the CO-toH2 conversion factor XCO in NGC 6946. Donovan Meyer et al. (2012) derived an XCO similar to the Milky Way (MW) value (4.4 M☉pc−2 (K km s−1)−1; Sandstrom et al. 2013) by assuming that GMCs we ...
Session 1: Stellar winds, diagnostics across the electromagnetic
... Polarimetry is an important observational technique in the study of hot stars. Practiced across the full range of wavelengths, polarimetry provides a window into a variety of stellar phenomena not accessible by other means. For example, polarimetry constrains the properties of circumstellar disks, u ...
... Polarimetry is an important observational technique in the study of hot stars. Practiced across the full range of wavelengths, polarimetry provides a window into a variety of stellar phenomena not accessible by other means. For example, polarimetry constrains the properties of circumstellar disks, u ...
ongoing massive star formation in the bulge of m511 hjglm lamers,2
... formation suggest that isolated massive stars might be formed in clouds in which H , [O I] 63 km and [C II] 158 km are the dominant coolants. This is expected to occur in regions of2 rather low optical depth, A ¹ 1, with a hot source that can dissociate the CO molecules. These conditions are met in ...
... formation suggest that isolated massive stars might be formed in clouds in which H , [O I] 63 km and [C II] 158 km are the dominant coolants. This is expected to occur in regions of2 rather low optical depth, A ¹ 1, with a hot source that can dissociate the CO molecules. These conditions are met in ...
Red supergiants around the obscured open cluster Stephenson 2
... other RSG clusters is unclear. Though all the clusters are located at a similar distance and have similar ages, they span ∼500 pc in projection. There have been suggestions that this Scutum Complex represents a giant star formation region triggered by the dynamical excitation of the Galactic Bar, wh ...
... other RSG clusters is unclear. Though all the clusters are located at a similar distance and have similar ages, they span ∼500 pc in projection. There have been suggestions that this Scutum Complex represents a giant star formation region triggered by the dynamical excitation of the Galactic Bar, wh ...
A search for debris disks in the Herschel
... to reject the presence of possible contaminating galaxies, and the wider field of the H-ATLAS SPIRE images to search for contaminating cirrus. We stress that our search technique reveals candidate disks. Spectroscopic confirmation of the host star spectral types, more accurate spectrophotometric dis ...
... to reject the presence of possible contaminating galaxies, and the wider field of the H-ATLAS SPIRE images to search for contaminating cirrus. We stress that our search technique reveals candidate disks. Spectroscopic confirmation of the host star spectral types, more accurate spectrophotometric dis ...
12C13C1414N21312C/13C3he43He/4He Sub-surface
... evolution of hot massive stars, they may cause observable phenomena at the stellar surface. The reason is that the zones are located very close to the photosphere for some mass interval (see below). Here, we will discuss which observed features in hot stars might be produced by these near surface co ...
... evolution of hot massive stars, they may cause observable phenomena at the stellar surface. The reason is that the zones are located very close to the photosphere for some mass interval (see below). Here, we will discuss which observed features in hot stars might be produced by these near surface co ...
The DBV stars: Progress and problems
... While it is possible that most or all of the cooler (Teff < 20,000 K) DA white dwarfs are the spawn of hydrogen-rich planetary nebula nuclei, the picture is less certain for the DBV and DB ’whitedwarfs. There are at least two possible progenitors of DB white dwarfs: the PG 1159 stars and the interac ...
... While it is possible that most or all of the cooler (Teff < 20,000 K) DA white dwarfs are the spawn of hydrogen-rich planetary nebula nuclei, the picture is less certain for the DBV and DB ’whitedwarfs. There are at least two possible progenitors of DB white dwarfs: the PG 1159 stars and the interac ...
The Sun and Stars 4.1 Energy formation and layers of the Sun 4.2
... Prominences and Solar Flares. It is important for us to follow the Sunspot cycle to know when there is going to be an increase in Sunspots, because they cause Solar Flares and Prominences. Although the Earth’s magnetic field can deflect or pull in much of the energy that is carried in a solar flare, ...
... Prominences and Solar Flares. It is important for us to follow the Sunspot cycle to know when there is going to be an increase in Sunspots, because they cause Solar Flares and Prominences. Although the Earth’s magnetic field can deflect or pull in much of the energy that is carried in a solar flare, ...
Superbubble Activity in Star-Forming Galaxies M. S. Oey
... will cool and depart from energy conservation. Indeed, whether and how the hot interior cools has long been a major question for superbubble evolution and the fate of the hot gas. Thermal conduction at the interface between the cool shell wall and hot gas should cause a high rate of mass-loading int ...
... will cool and depart from energy conservation. Indeed, whether and how the hot interior cools has long been a major question for superbubble evolution and the fate of the hot gas. Thermal conduction at the interface between the cool shell wall and hot gas should cause a high rate of mass-loading int ...
ASTRONOMY AND ASTROPHYSICS Barium abundances in cool
... them with the predictions of theoretical models. From inspection of those data two features can be seen. Firstly, the trend of [Ba/Fe] with [Fe/H] at [Fe/H] < ; : . For the extremely metal-poor stars ([Fe/H] < ; : ) barium is underabundant relative to iron by ; : dex, and [Ba/Fe] grows with increasi ...
... them with the predictions of theoretical models. From inspection of those data two features can be seen. Firstly, the trend of [Ba/Fe] with [Fe/H] at [Fe/H] < ; : . For the extremely metal-poor stars ([Fe/H] < ; : ) barium is underabundant relative to iron by ; : dex, and [Ba/Fe] grows with increasi ...
The (galaxy-wide) IMF in giant elliptical galaxies: from top to bottom
... numbers compare well with the hypothesis that all these galaxies have similar IMFs. Additionally, very little impact seems to come from the total luminosity (and hence mass) or morphological type, a conclusion shared by Zhang et al. (2011). For field LMXBs, less information is available. When roughl ...
... numbers compare well with the hypothesis that all these galaxies have similar IMFs. Additionally, very little impact seems to come from the total luminosity (and hence mass) or morphological type, a conclusion shared by Zhang et al. (2011). For field LMXBs, less information is available. When roughl ...
Astronomy and Astrophysics 336, 972, 1998
... a smaller total overall area than either the spots in the maps recovered from lines of intermediate strength or those from the lines of the greatest strength. The greater uncertainty expressed by the lighter shade of grey in the “consistency map” of Fig. 2b is simply a reflection of these variations ...
... a smaller total overall area than either the spots in the maps recovered from lines of intermediate strength or those from the lines of the greatest strength. The greater uncertainty expressed by the lighter shade of grey in the “consistency map” of Fig. 2b is simply a reflection of these variations ...
A timeline of the universe
... consists primarily of bare hydrogen nuclei and free electrons. Stellar UV light maintains this ionization. These photons pack enough punch to tear electrons off any neutral hydrogen atoms that form by recombination. The current dominance of ionized hydrogen is one reason we can see so far with opti ...
... consists primarily of bare hydrogen nuclei and free electrons. Stellar UV light maintains this ionization. These photons pack enough punch to tear electrons off any neutral hydrogen atoms that form by recombination. The current dominance of ionized hydrogen is one reason we can see so far with opti ...
Testing - uwyo.edu
... that formed the first stars had to be considerably warmer than today’s molecular clouds. • The first stars must therefore have been more massive than most of today’s stars, for gravity to overcome pressure. © 2010 Pearson Education, Inc. ...
... that formed the first stars had to be considerably warmer than today’s molecular clouds. • The first stars must therefore have been more massive than most of today’s stars, for gravity to overcome pressure. © 2010 Pearson Education, Inc. ...
Seeds of a Tychonic Revolution: Telescopic Observations of the
... Graney, Seeds of a Tychonic Revolution page viii ...
... Graney, Seeds of a Tychonic Revolution page viii ...
Pre-main sequence stars, emission stars and recent star formation in
... Cygnus region, located between 70◦ < l < 80◦ is a region of recent star formation activity in the Milky Way and is rich in massive early type stars concentrated in OB associations. The presence of nebulosity and massive stars indicate that the stars have been forming till very recently and the young ...
... Cygnus region, located between 70◦ < l < 80◦ is a region of recent star formation activity in the Milky Way and is rich in massive early type stars concentrated in OB associations. The presence of nebulosity and massive stars indicate that the stars have been forming till very recently and the young ...
Article PDF - IOPscience
... Wide Field Planetary Camera 2 (WFPC2) archive observations. However, the number of phase points and the time window of these archive data were too sparse to allow the derivation of the variable stars’ periods. Thus, we do not know yet whether the M31 GCs show the Oosterhoff dichotomy, or whether ind ...
... Wide Field Planetary Camera 2 (WFPC2) archive observations. However, the number of phase points and the time window of these archive data were too sparse to allow the derivation of the variable stars’ periods. Thus, we do not know yet whether the M31 GCs show the Oosterhoff dichotomy, or whether ind ...
ATLAS lifts the Cup: discovery of a new Milky Way satellite in Crater⋆†
... No globular cluster has ever accomplished the feat of prolonging its star formation by several Gyr. Therefore, if our hypothesis that the blue bright stars in Crater are blue loop giants is correct, the new satellite should be classified as a dwarf galaxy with unusual properties. Note that only 10◦ ...
... No globular cluster has ever accomplished the feat of prolonging its star formation by several Gyr. Therefore, if our hypothesis that the blue bright stars in Crater are blue loop giants is correct, the new satellite should be classified as a dwarf galaxy with unusual properties. Note that only 10◦ ...
UNIVERSITY OF PADUA Master degree in
... recent surveys of the distribution of CO gas in the Milky Way [13]. Molecular clouds have also been identified and cataloged from CO observations of Milky Way [41]. Shown in figure 1.1 is the distribution of CO gas along the galactic plane. In other spiral galaxies it is observed that molecular clou ...
... recent surveys of the distribution of CO gas in the Milky Way [13]. Molecular clouds have also been identified and cataloged from CO observations of Milky Way [41]. Shown in figure 1.1 is the distribution of CO gas along the galactic plane. In other spiral galaxies it is observed that molecular clou ...
Properties of simulated Milky Way-mass galaxies in loose group and
... Aims. We test the validity of comparing simulated field disk galaxies with the empirical properties of systems situated within environments more comparable to loose groups, including the Milky Way’s Local Group. Methods. Cosmological simulations of Milky Way-mass galaxies have been realised in two d ...
... Aims. We test the validity of comparing simulated field disk galaxies with the empirical properties of systems situated within environments more comparable to loose groups, including the Milky Way’s Local Group. Methods. Cosmological simulations of Milky Way-mass galaxies have been realised in two d ...
H II region
An H II region is a large, low-density cloud of partially ionized gas in which star formation has recently taken place. The short-lived blue stars forged in these regions emit copious amounts of ultraviolet light that ionize the surrounding gas. H II regions—sometimes several hundred light-years across—are often associated with giant molecular clouds. The first known H II region was the Orion Nebula, which was discovered in 1610 by Nicolas-Claude Fabri de Peiresc.H II regions are named for the large amount of ionised atomic hydrogen they contain, referred to as H II, pronounced H-two by astronomers (an H I region being neutral atomic hydrogen, and H2 being molecular hydrogen). Such regions have extremely diverse shapes, because the distribution of the stars and gas inside them is irregular. They often appear clumpy and filamentary, sometimes showing bizarre shapes such as the Horsehead Nebula. H II regions may give birth to thousands of stars over a period of several million years. In the end, supernova explosions and strong stellar winds from the most massive stars in the resulting star cluster will disperse the gases of the H II region, leaving behind a cluster of birthed stars such as the Pleiades.H II regions can be seen to considerable distances in the universe, and the study of extragalactic H II regions is important in determining the distance and chemical composition of other galaxies. Spiral and irregular galaxies contain many H II regions, while elliptical galaxies are almost devoid of them. In the spiral galaxies, including the Milky Way, H II regions are concentrated in the spiral arms, while in the irregular galaxies they are distributed chaotically. Some galaxies contain huge H II regions, which may contain tens of thousands of stars. Examples include the 30 Doradus region in the Large Magellanic Cloud and NGC 604 in the Triangulum Galaxy.