JOA Vol 1 No. 2 - Apr 2011 - RASNZ Occultation Section
... the early morning. The path covered Poland, Germany, France, Spain and Portugal. The star 2UCAC 39795518 (11.2 mag) was predicted to be occulted for about 6 seconds. The expected drop of 0.9 mag was small but the combined light of asteroid and star (10.6 mag) was detectible for my setup (video camer ...
... the early morning. The path covered Poland, Germany, France, Spain and Portugal. The star 2UCAC 39795518 (11.2 mag) was predicted to be occulted for about 6 seconds. The expected drop of 0.9 mag was small but the combined light of asteroid and star (10.6 mag) was detectible for my setup (video camer ...
Hubble Space Telescope Astrometry of the Procyon System
... the mass-radius plane is also consistent with theory, assuming a carbon-oxygen core and a helium-dominated atmosphere. Its progenitor’s mass was 1.9–2.2 M⊙ , depending on its amount of core overshoot. Several astrophysical puzzles remain. In the progenitor system, the stars at periastron were separa ...
... the mass-radius plane is also consistent with theory, assuming a carbon-oxygen core and a helium-dominated atmosphere. Its progenitor’s mass was 1.9–2.2 M⊙ , depending on its amount of core overshoot. Several astrophysical puzzles remain. In the progenitor system, the stars at periastron were separa ...
diplomov a prace - Univerzita Karlova
... dwarfs are relatively small and very dim /cool stars of the main sequence. Its spec tral type is late K or M. Red dwarfs are smaller than the Sun, their mass varies from 0.075 M© to 0.5 M0 (these are called brown dwarves). With less matter the pull of gravity on the core is lower and accordingly th ...
... dwarfs are relatively small and very dim /cool stars of the main sequence. Its spec tral type is late K or M. Red dwarfs are smaller than the Sun, their mass varies from 0.075 M© to 0.5 M0 (these are called brown dwarves). With less matter the pull of gravity on the core is lower and accordingly th ...
Photometric Variability and Rotation in Magnetic White Dwarfs
... emerged between the spin period and magnetic field strength and temperature, suggesting hotter MWDs spin faster and have higher field strengths, characteristics possibly associated with MWDs that might have formed in binary mergers. A similar investigation is carried out on longer timescales (months ...
... emerged between the spin period and magnetic field strength and temperature, suggesting hotter MWDs spin faster and have higher field strengths, characteristics possibly associated with MWDs that might have formed in binary mergers. A similar investigation is carried out on longer timescales (months ...
Link - Max-Planck-Institut für Astronomie
... the star formation community. It is now viewed as a common, though still poorly understood, phenomenon in low-mass star formation. The FU Orionis objects (FUors) are long-studied examples of this phenomenon. FUors are believed to undergo accretion outbursts during which the accretion rate rapidly in ...
... the star formation community. It is now viewed as a common, though still poorly understood, phenomenon in low-mass star formation. The FU Orionis objects (FUors) are long-studied examples of this phenomenon. FUors are believed to undergo accretion outbursts during which the accretion rate rapidly in ...
A subaru/suprime-cam wide
... centre) of GCs around M87 with Subaru/Suprime-Cam Secure selection of GC candidates with an extended source cut and a colour selection on the B-V vs. V-I diagram. Analyzed the Suprime-Cam data on the control fields through the BVI bands, which enable to select contaminating objects with the identica ...
... centre) of GCs around M87 with Subaru/Suprime-Cam Secure selection of GC candidates with an extended source cut and a colour selection on the B-V vs. V-I diagram. Analyzed the Suprime-Cam data on the control fields through the BVI bands, which enable to select contaminating objects with the identica ...
Formation and evolution of giant molecular clouds in a barred spiral
... and star formation, while also taking global galactic dynamics into account. Thanks to high resolution and sensitive observations from sources such as the millimeter/submillimeter observations by ALMA and infrared observations by Spitzer and Herschel, it is becoming possible to statistically explore ...
... and star formation, while also taking global galactic dynamics into account. Thanks to high resolution and sensitive observations from sources such as the millimeter/submillimeter observations by ALMA and infrared observations by Spitzer and Herschel, it is becoming possible to statistically explore ...
Contents - arXiv.org
... Commonly it is assumed that light deflection is a modern phenomenon. However, more than 200 years ago scientists started to think about it. In the beginning of the 19th century, Johann Georg Soldner wrote an article entitled “Über den Einfluß der Schwerkraft auf die Ausbreitung des Lichtes”1 , in w ...
... Commonly it is assumed that light deflection is a modern phenomenon. However, more than 200 years ago scientists started to think about it. In the beginning of the 19th century, Johann Georg Soldner wrote an article entitled “Über den Einfluß der Schwerkraft auf die Ausbreitung des Lichtes”1 , in w ...
Cepheids
... HIPPARCOS catalogue and the distance to the LMC” (A&A V.356, P.849, 2000) • A.Sandage et al. “The Hubble constant: a summary of the HST program for the luminosity calibration of type Ia SuperNovae by means of Cepheids” (ApJ V.653, P.843, 2006) • F.van Leeuwen et al. “Cepheid parallaxes and the Hubbl ...
... HIPPARCOS catalogue and the distance to the LMC” (A&A V.356, P.849, 2000) • A.Sandage et al. “The Hubble constant: a summary of the HST program for the luminosity calibration of type Ia SuperNovae by means of Cepheids” (ApJ V.653, P.843, 2006) • F.van Leeuwen et al. “Cepheid parallaxes and the Hubbl ...
L117 SHOCK-HEATED NH3 IN A MOLECULAR JET ASSOCIATED
... at high forward velocities along the jet direction is probably the result of disassociation: The NH3 molecules are destroyed if the shock velocities are too high. In the extreme case of nonradiative J-type shocks, for instance, the velocity of the postshock gas vps is (3/4)vs, where vs is the shock ...
... at high forward velocities along the jet direction is probably the result of disassociation: The NH3 molecules are destroyed if the shock velocities are too high. In the extreme case of nonradiative J-type shocks, for instance, the velocity of the postshock gas vps is (3/4)vs, where vs is the shock ...
Accretion Power in Astrophysics, Third Editiion
... where G is the gravitation constant. If the accreting body is a neutron star with radius R∗ ∼ 10 km, mass M ∼ M , the solar mass, then the yield ∆Eacc is about 1020 erg per accreted gram. We would expect this energy to be released eventually mainly in the form of electromagnetic radiation. For comp ...
... where G is the gravitation constant. If the accreting body is a neutron star with radius R∗ ∼ 10 km, mass M ∼ M , the solar mass, then the yield ∆Eacc is about 1020 erg per accreted gram. We would expect this energy to be released eventually mainly in the form of electromagnetic radiation. For comp ...
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.