Seeds of a Tychonic Revolution: Telescopic Observations of the
... have disks that are less than half the size of the brightest stars, and so must be more than twice as far away. In fact, the faintest stars visible to the naked eye, whose diameters, as seen through Mareo's telescope, are an arcsecond or less, must be two thousand or more AU distant. Very faint star ...
... have disks that are less than half the size of the brightest stars, and so must be more than twice as far away. In fact, the faintest stars visible to the naked eye, whose diameters, as seen through Mareo's telescope, are an arcsecond or less, must be two thousand or more AU distant. Very faint star ...
The age structure of the Milky Way`s halo
... The yellow/orange-coloured features in panels a and b of Fig. 1 may be portions of the Styx Stream33,34 (labelled with Styx). The Orphan Stream35 is associated with a blue-coloured feature in panel a and b (labelled with an O). Both streams cover a range of ages of 10-11 Gyr. Panel a also shows a bl ...
... The yellow/orange-coloured features in panels a and b of Fig. 1 may be portions of the Styx Stream33,34 (labelled with Styx). The Orphan Stream35 is associated with a blue-coloured feature in panel a and b (labelled with an O). Both streams cover a range of ages of 10-11 Gyr. Panel a also shows a bl ...
Ground-Based Astrometry 2010-2020
... 2MASS, and DENIS have provided significant datasets using modern CCD and infrared array detectors. The next generation of ground-based sky surveys is imminent, and these efforts will produce substantial science before, in parallel, and beyond (in both time and phase space) what space missions promi ...
... 2MASS, and DENIS have provided significant datasets using modern CCD and infrared array detectors. The next generation of ground-based sky surveys is imminent, and these efforts will produce substantial science before, in parallel, and beyond (in both time and phase space) what space missions promi ...
General Astronomy Dark Matter
... see directly. Unless, that is, if they were VERY old. • Imagine that the very first objects to form in the universe were an incredible number of medium mass stars. – These would have formed about 15 billion years ago, out of the primordial gas. – Quite rapidly they would have died and turned into wh ...
... see directly. Unless, that is, if they were VERY old. • Imagine that the very first objects to form in the universe were an incredible number of medium mass stars. – These would have formed about 15 billion years ago, out of the primordial gas. – Quite rapidly they would have died and turned into wh ...
HST observations of the field star population in the Large Magellanic
... (1995) and Vallenari et al. (1996a,b). Bertelli et al. examined three regions ~ 5° from the centre of the LMC, with photometry to Vo ~ 23. Their data suggest a global burst of star formation 2-4 Gyr ago, with the exact timing depending on the choice of stellar evolution models. Vallenari et al. use ...
... (1995) and Vallenari et al. (1996a,b). Bertelli et al. examined three regions ~ 5° from the centre of the LMC, with photometry to Vo ~ 23. Their data suggest a global burst of star formation 2-4 Gyr ago, with the exact timing depending on the choice of stellar evolution models. Vallenari et al. use ...
ASTRONOMY AND ASTROPHYSICS Barium abundances in cool
... results of Magain (1989) or Peterson et al. (1990). Such discrepances are probably arising from the use of giants and supergiants in most of the studies due to the fact that Ba II lines are more easily measured in spectra of luminous stars than in dwarfs. But two points should be carefully considere ...
... results of Magain (1989) or Peterson et al. (1990). Such discrepances are probably arising from the use of giants and supergiants in most of the studies due to the fact that Ba II lines are more easily measured in spectra of luminous stars than in dwarfs. But two points should be carefully considere ...
Lecture 2. Thermal evolution and surface emission of
... Exotic phase transition Rapid cooling of Cas A can be understood as a phase transition from the perfect 2SC phase to a crystalline/gapless color-superconducting state ...
... Exotic phase transition Rapid cooling of Cas A can be understood as a phase transition from the perfect 2SC phase to a crystalline/gapless color-superconducting state ...
Slide 1
... SNe-Ia seen in low-metallicity galaxies, counter to Kobayashi prediction (Prieto+ 2007) CSM found in only 1 SN-Ia (2006X, Patat+ 2007, but see Crotts & Yourdon 2008), not others No clear ID of remaining companion in Tycho (Ruiz-Lapuente+ 2004, Fuhrman 2005, Ihara+ 2007) ...
... SNe-Ia seen in low-metallicity galaxies, counter to Kobayashi prediction (Prieto+ 2007) CSM found in only 1 SN-Ia (2006X, Patat+ 2007, but see Crotts & Yourdon 2008), not others No clear ID of remaining companion in Tycho (Ruiz-Lapuente+ 2004, Fuhrman 2005, Ihara+ 2007) ...
observation reports
... Conditions: clear but chilly with a light NW wind, 8°C Time: 21:00 – 00:20 UT, clear, ZLM 5.2 – 5.3 by 22:00 UT, seeing 7-8 TWO fine nights of viewing, getting too good to be true. This was a 5.2 - 5.3 night, perfect for seeking out finer detail in globulars, and looking out for elusive galaxies. 21 ...
... Conditions: clear but chilly with a light NW wind, 8°C Time: 21:00 – 00:20 UT, clear, ZLM 5.2 – 5.3 by 22:00 UT, seeing 7-8 TWO fine nights of viewing, getting too good to be true. This was a 5.2 - 5.3 night, perfect for seeking out finer detail in globulars, and looking out for elusive galaxies. 21 ...
PowerPoint
... • Doppler shift– toward (blue) and away (red) • Quantum mechanics– electrons can be wave-like – Electrons around nucleus have certain orbits– defines emission and absorption of each atom – When excited, atoms emit certain lines (like in class)– fingerprint or barcode of atom ...
... • Doppler shift– toward (blue) and away (red) • Quantum mechanics– electrons can be wave-like – Electrons around nucleus have certain orbits– defines emission and absorption of each atom – When excited, atoms emit certain lines (like in class)– fingerprint or barcode of atom ...
Binary progenitor models of type IIb supernovae
... 90% of the cases, as a result of mass accretion during its main sequence evolution, (2) the companion becomes an over-luminous B star in about 3% of the cases, if mass accretion occurred while crossing the Hertzsprung gap or (3) in systems with very similar initial masses the companion will appear a ...
... 90% of the cases, as a result of mass accretion during its main sequence evolution, (2) the companion becomes an over-luminous B star in about 3% of the cases, if mass accretion occurred while crossing the Hertzsprung gap or (3) in systems with very similar initial masses the companion will appear a ...
ongoing massive star formation in the bulge of m511 hjglm lamers,2
... e.g., Millard et al. 1999). The galaxy was observed through the broadband Ðlters F255W and F336W in 1994 and through the broadband Ðlters F439W, F555W, F675W, and F814W in 1995. We will refer to these Ðlters as the UV, U, B, V , R, and I Ðlters. The observations in the UV, U, and B Ðlters were split ...
... e.g., Millard et al. 1999). The galaxy was observed through the broadband Ðlters F255W and F336W in 1994 and through the broadband Ðlters F439W, F555W, F675W, and F814W in 1995. We will refer to these Ðlters as the UV, U, B, V , R, and I Ðlters. The observations in the UV, U, and B Ðlters were split ...
Runaway collisions in young star clusters – II. Numerical results
... with α = 2.35, M min = 0.2 M and M max = 120 M . For this stellar population, the average mass is M∗ 0.69 M . There is no initial mass segregation. To investigate the role of the initial concentration of the cluster, we consider King models with W0 = 3 or 8 (Binney & Tremaine 1987, Section 4 ...
... with α = 2.35, M min = 0.2 M and M max = 120 M . For this stellar population, the average mass is M∗ 0.69 M . There is no initial mass segregation. To investigate the role of the initial concentration of the cluster, we consider King models with W0 = 3 or 8 (Binney & Tremaine 1987, Section 4 ...
Final Paper Template for the 5th Southeast Asian Forum
... Milky Way galaxy hosts more than 2000 open clusters. Some of them are evolved clusters that dissolved by Galactic tidal field, leave behind only few members and known as Open Cluster Remnants (OCR). They have very low surface density but high binary fraction. One of well-studied OCRs is NGC 1901 (α ...
... Milky Way galaxy hosts more than 2000 open clusters. Some of them are evolved clusters that dissolved by Galactic tidal field, leave behind only few members and known as Open Cluster Remnants (OCR). They have very low surface density but high binary fraction. One of well-studied OCRs is NGC 1901 (α ...
High-precision abundances of elements in solar twin stars: Trends
... Context. High-precision determinations of abundances of elements in the atmospheres of the Sun and solar twin stars indicate that the Sun has an unusual low ratio between refractory and volatile elements. This has led to the suggestion that the relation between abundance ratios, [X/Fe], and elementa ...
... Context. High-precision determinations of abundances of elements in the atmospheres of the Sun and solar twin stars indicate that the Sun has an unusual low ratio between refractory and volatile elements. This has led to the suggestion that the relation between abundance ratios, [X/Fe], and elementa ...
Binary star progenitors of long GRBs
... Fast rotating massive stars can evolve chemically homogeneous and become long GRBs Two classes of progenitors: single and binary stars In massive binaries it’s possible to spin up a star and ...
... Fast rotating massive stars can evolve chemically homogeneous and become long GRBs Two classes of progenitors: single and binary stars In massive binaries it’s possible to spin up a star and ...
Explosion and Systematics for Core
... Therefore, predictions of the initial-final remnant mass function and of explosive nucleosynthesis are still based on very simple and physically inaccurate methods to initiate the explosions. We propose a novel approach to the study the connection between progenitors and the properties of core-colla ...
... Therefore, predictions of the initial-final remnant mass function and of explosive nucleosynthesis are still based on very simple and physically inaccurate methods to initiate the explosions. We propose a novel approach to the study the connection between progenitors and the properties of core-colla ...
jordi_so
... Progress report on the determination of absolute magnitudes using Strömgren photometry. ...
... Progress report on the determination of absolute magnitudes using Strömgren photometry. ...
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.