![arXiv:1705.00964v1 [astro-ph.GA] 2 May 2017](http://s1.studyres.com/store/data/013011793_1-8f89fb3e8b5cd5cf78613aebb3c8e2a5-300x300.png)
arXiv:1705.00964v1 [astro-ph.GA] 2 May 2017
... able that this close positional coincidence would occur by chance. We were also aware of the suggestion of Dennett-Thorpe and de Bruyn (2002), that the IDV of J1819+3845 might be related to the foreground, bright star Vega. We therefore examined whether ionized gas associated with foreground stars p ...
... able that this close positional coincidence would occur by chance. We were also aware of the suggestion of Dennett-Thorpe and de Bruyn (2002), that the IDV of J1819+3845 might be related to the foreground, bright star Vega. We therefore examined whether ionized gas associated with foreground stars p ...
How Marius Was Right and Galileo Was Wrong Even Though
... these ideas will require further discussion and explanation. Lastly, he concedes to Galileo that the stars shine by their own light -- they are distinct in appearance from the planets (being notably more intense in brilliance).13 ...
... these ideas will require further discussion and explanation. Lastly, he concedes to Galileo that the stars shine by their own light -- they are distinct in appearance from the planets (being notably more intense in brilliance).13 ...
script
... idea will be very strange to many members of your audience. One suggestion for making them more comfortable with this idea is to ask them how far away something is. For example: How far away is the front desk of your museum? How far away is the next nearest major city? Some audience members will ans ...
... idea will be very strange to many members of your audience. One suggestion for making them more comfortable with this idea is to ask them how far away something is. For example: How far away is the front desk of your museum? How far away is the next nearest major city? Some audience members will ans ...
Observing Stellar Evolution
... Stellar evolution – refers to the stages in the lifetime of one star. When biologists talk about evolution they mean intergenerational evolution. While stars change from one generation to the next, the focus of this program is stellar lifetimes. Burning – The materials that comprise stars do not 'bu ...
... Stellar evolution – refers to the stages in the lifetime of one star. When biologists talk about evolution they mean intergenerational evolution. While stars change from one generation to the next, the focus of this program is stellar lifetimes. Burning – The materials that comprise stars do not 'bu ...
STIS/HST Observations of Large Magellanic Cloud Planetary
... Let us now examine the cases in which the electron density of the PNs is higher than the critical density. In Fig. 4 (top panels) we plot the usual SB vs. Rphot relation, from the observations in the light of [S II]. The critical densities, calculated for a model nebula with Te ~ 10,000 K and Ne ~ 1 ...
... Let us now examine the cases in which the electron density of the PNs is higher than the critical density. In Fig. 4 (top panels) we plot the usual SB vs. Rphot relation, from the observations in the light of [S II]. The critical densities, calculated for a model nebula with Te ~ 10,000 K and Ne ~ 1 ...
... change? Well, this increase is primarily due to the humanmade greenhouse gases. Levels of CO2 have increased from around 280 parts per million (ppm) to around 380 ppm now. Studies of ice core show that concentrations of CO2 have not been so high for nearly half a million years. At the current rate o ...
The Formation of Massive Stars - Max-Planck
... in our galaxy shows that the average local density derived from an LVG analysis is nH ~ 4 × 103–1.2 × 104 cm–3 and the temperature is ~10–15 K (e.g., Sanders et al., 1993), giving a typical Bonnor-Ebert mass ~2 M . The volumeaveraged densities in GMCs are nH ~ 50 to 100 cm–3; these are substantially ...
... in our galaxy shows that the average local density derived from an LVG analysis is nH ~ 4 × 103–1.2 × 104 cm–3 and the temperature is ~10–15 K (e.g., Sanders et al., 1993), giving a typical Bonnor-Ebert mass ~2 M . The volumeaveraged densities in GMCs are nH ~ 50 to 100 cm–3; these are substantially ...
The Galactic evolution of phosphorus
... planets” it cannot be excluded that they harbour undetected planets. We note, however, that all of the stars “without planets” in our sample, except for HD 215648 and HD 207978 have several high precision radial velocity points measured with the HARPS spectrograph at the ESO 3.6 m telescope. Given t ...
... planets” it cannot be excluded that they harbour undetected planets. We note, however, that all of the stars “without planets” in our sample, except for HD 215648 and HD 207978 have several high precision radial velocity points measured with the HARPS spectrograph at the ESO 3.6 m telescope. Given t ...
An interesting nebular object in LDN 288
... A multiwavelength investigation of a star-forming region embedded in the dark cloud LDN 288 was carried out. There are several objects in this region: a B type star GSC 0625400181 surrounded by an HII region (object 2 in Fig.2), a star with a straight jet (object 3 in Fig.2), and a unique object SNO ...
... A multiwavelength investigation of a star-forming region embedded in the dark cloud LDN 288 was carried out. There are several objects in this region: a B type star GSC 0625400181 surrounded by an HII region (object 2 in Fig.2), a star with a straight jet (object 3 in Fig.2), and a unique object SNO ...
with answers
... producing enough light to outshine a galaxy. When two atomic nuclei join to form a new, heavier nucleus and release energy. A type of fusion that occurs due to the extreme high temperatures in stars or in thermonuclear weapons. The process of creating new atomic nuclei from the fusion of smaller nuc ...
... producing enough light to outshine a galaxy. When two atomic nuclei join to form a new, heavier nucleus and release energy. A type of fusion that occurs due to the extreme high temperatures in stars or in thermonuclear weapons. The process of creating new atomic nuclei from the fusion of smaller nuc ...
margarita2007
... account for all the large scale features of the observable universe, including the details of ...
... account for all the large scale features of the observable universe, including the details of ...
MAIN SEQUENCE STARS, Red Giants and White Dwarfs
... reactions will occur • Most such stars will have Oxygen cores that can also fuse, typically needs T > 1 x 109 K! • 16O + 4He 20Ne + • 20Ne + 4He 24Mg + • We’ll come back to this type of onion-layer model star when we talk about supernova explosions and neutron stars. • The elements cooked he ...
... reactions will occur • Most such stars will have Oxygen cores that can also fuse, typically needs T > 1 x 109 K! • 16O + 4He 20Ne + • 20Ne + 4He 24Mg + • We’ll come back to this type of onion-layer model star when we talk about supernova explosions and neutron stars. • The elements cooked he ...
Asteroseismology of Solar-Like Stars
... (pressure) modes. In gravity modes the restoring force for the oscillation is the gradient of the gravitational acceleration within the star, they are also known as buoyancy waves. A parcel of gas within a star will rise if the material is less dense than of its surroundings. The g mode oscillations ...
... (pressure) modes. In gravity modes the restoring force for the oscillation is the gradient of the gravitational acceleration within the star, they are also known as buoyancy waves. A parcel of gas within a star will rise if the material is less dense than of its surroundings. The g mode oscillations ...
IAU-Perraut-2013 - Putting A Stars into Context
... measurement but this technique can also be used to study the environments of A stars: Study debris disks around VEGA-like Search for companion(s) ...
... measurement but this technique can also be used to study the environments of A stars: Study debris disks around VEGA-like Search for companion(s) ...
A Hero`s Little Horse: Discovery of a Dissolving Star Cluster in
... and metal-poor ([Fe/H]∼ −1.7) stellar population at a heliocentric distance of 19.8 ± 0.9 kpc. We measure a half-light radius of 6.9 ± 0.6 pc using a Plummer profile. The small physical size and the extremely low luminosity are comparable to the faintest known star clusters Segue 3, Koposov 1 & 2, a ...
... and metal-poor ([Fe/H]∼ −1.7) stellar population at a heliocentric distance of 19.8 ± 0.9 kpc. We measure a half-light radius of 6.9 ± 0.6 pc using a Plummer profile. The small physical size and the extremely low luminosity are comparable to the faintest known star clusters Segue 3, Koposov 1 & 2, a ...
Discovery of extremely lead-rich subdwarfs: does heavy metal signal
... evolution theory suggests that they should have helium-rich atmospheres but, because radiation causes hydrogen to diffuse upwards, a majority are extremely helium poor. Questions posed include: when does the atmosphere become chemically stratified and at what rate? The existence of several helium-ri ...
... evolution theory suggests that they should have helium-rich atmospheres but, because radiation causes hydrogen to diffuse upwards, a majority are extremely helium poor. Questions posed include: when does the atmosphere become chemically stratified and at what rate? The existence of several helium-ri ...
20_LectureOutline
... • When fusion ceases in the core, it begins to collapse and heat. Hydrogen fusion starts in the shell surrounding the core. • The helium core begins to heat up; as long as the star is at least 0.25 solar masses, the helium will get hot enough that fusion (to carbon) will start. • As the core collaps ...
... • When fusion ceases in the core, it begins to collapse and heat. Hydrogen fusion starts in the shell surrounding the core. • The helium core begins to heat up; as long as the star is at least 0.25 solar masses, the helium will get hot enough that fusion (to carbon) will start. • As the core collaps ...
The Primeval Populations of the Ultra
... the effects of He diffusion, the latest improvements to the Hburning nuclear reaction rates, and an update to the Asplund et al. (2009) solar metals mixture. The net effect of these changes is to reduce the age at a given turnoff luminosity by ∼0.5 Gyr. Our purpose here is to use these isochrones to ...
... the effects of He diffusion, the latest improvements to the Hburning nuclear reaction rates, and an update to the Asplund et al. (2009) solar metals mixture. The net effect of these changes is to reduce the age at a given turnoff luminosity by ∼0.5 Gyr. Our purpose here is to use these isochrones to ...
The AG Carinae nebula: abundant evidence for a red supergiant
... nebular abundances should reflect the surface composition of the star at the time of the eruption. Garcia-Segura, Mac Low & Langer (1996a) have followed the dynamical interaction of a 60-M0 star with its environment as it evolves through the LBV phase to a WR star. They predict that the nebula forme ...
... nebular abundances should reflect the surface composition of the star at the time of the eruption. Garcia-Segura, Mac Low & Langer (1996a) have followed the dynamical interaction of a 60-M0 star with its environment as it evolves through the LBV phase to a WR star. They predict that the nebula forme ...
Solar system formation by accretion has no observational evidence
... one theorist could say only that “there is no complete theory of cloud formation yet”.39 Jeffreys once lamented, “To sum up, I think that all suggested accounts of the origin of the Solar System are subject to serious objections. The conclusion in the present state of the subject would be that the s ...
... one theorist could say only that “there is no complete theory of cloud formation yet”.39 Jeffreys once lamented, “To sum up, I think that all suggested accounts of the origin of the Solar System are subject to serious objections. The conclusion in the present state of the subject would be that the s ...
Chapter 7 Formation of metal-enriched 2nd generation objects 7.1
... pressure-balanced with the IGM after metal has spread several hundred parsecs from the initial halo. Comparison of the leftmost and rightmost columns shows that metal has spread to at least the distance of the nearest neighboring halos, though it is unclear at present how much metal has managed to g ...
... pressure-balanced with the IGM after metal has spread several hundred parsecs from the initial halo. Comparison of the leftmost and rightmost columns shows that metal has spread to at least the distance of the nearest neighboring halos, though it is unclear at present how much metal has managed to g ...
The Evening Sky Map
... Conjunction – An alignment of two celestial bodies such that they present the least angular separation as viewed from Earth. Constellation – A defined area of the sky containing a star pattern. Diffuse Nebula – A cloud of gas illuminated by nearby stars. Double Star – Two stars that appear close to ...
... Conjunction – An alignment of two celestial bodies such that they present the least angular separation as viewed from Earth. Constellation – A defined area of the sky containing a star pattern. Diffuse Nebula – A cloud of gas illuminated by nearby stars. Double Star – Two stars that appear close to ...
Star Formation in the Galaxy, An Observational Overview
... is again balanced by internal pressure. After this phase such stars will eject their outer atmospheres producing planetary nebula and leaving behind a white dwarf stellar remnant. More massive stars experience a more complex post-main sequence evolution during which they will fuse heavier elements i ...
... is again balanced by internal pressure. After this phase such stars will eject their outer atmospheres producing planetary nebula and leaving behind a white dwarf stellar remnant. More massive stars experience a more complex post-main sequence evolution during which they will fuse heavier elements i ...
Which Phase of the Interstellar Medium Corelates with the Star
... mass of H2 . At present observations possess limited power to discriminate between the models, although the limited data available for nearby low-metallicity dwarf galaxies such as the Small Magellanic Cloud hold out the promise of being able to distinguish whether metallicity affects star formation ...
... mass of H2 . At present observations possess limited power to discriminate between the models, although the limited data available for nearby low-metallicity dwarf galaxies such as the Small Magellanic Cloud hold out the promise of being able to distinguish whether metallicity affects star formation ...
Life Stages of High
... • This double-shell burning stage never reaches equilibrium—fusion rate periodically spikes upward in a series of thermal pulses ...
... • This double-shell burning stage never reaches equilibrium—fusion rate periodically spikes upward in a series of thermal pulses ...
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.