thesis
... Zinnecker & Yorke 2007, for a review). The reasons for this are the shorter time scale over which the formation of massive stars occurs, the smaller numbers of massive stars, and the greater distances between us and the nearest regions where massive stars are forming. As an additional consequence of ...
... Zinnecker & Yorke 2007, for a review). The reasons for this are the shorter time scale over which the formation of massive stars occurs, the smaller numbers of massive stars, and the greater distances between us and the nearest regions where massive stars are forming. As an additional consequence of ...
the origin of the hubble sequence - Yale Astronomy
... while if star formation is much slower or is delayed, most of the gas may settle into a disk before forming stars. Thus, an earlier Hubble type would be predicted to result when star formation proceeds more rapidly in relation to the collapse time. If the star formation rate depends on the gas densi ...
... while if star formation is much slower or is delayed, most of the gas may settle into a disk before forming stars. Thus, an earlier Hubble type would be predicted to result when star formation proceeds more rapidly in relation to the collapse time. If the star formation rate depends on the gas densi ...
Multiple Jets from the High-Mass (Proto) stellar Cluster AFGL5142
... contribution from the ionized gas at mm and submm wavelengths is ∼ 1999). Thus, dust emission dominates the 1.3mm continuum flux of all the sources, and likely does so to wavelengths as long as ∼ 3 mm. Because of a lack of high resolution images at more than one wavelength, the emissivity index of t ...
... contribution from the ionized gas at mm and submm wavelengths is ∼ 1999). Thus, dust emission dominates the 1.3mm continuum flux of all the sources, and likely does so to wavelengths as long as ∼ 3 mm. Because of a lack of high resolution images at more than one wavelength, the emissivity index of t ...
Stars, neutral hydrogen and ionised gas in early
... for the study of the relation between stellar and H i properties in early-type galaxies. We characterised the environment of IC 4200 by looking for extragalactic objects within 100 arcmin (∼1.6 Mpc at this redshift) and 300 km/s from the galaxy; for this search we used the Nasa Extragalactic Databas ...
... for the study of the relation between stellar and H i properties in early-type galaxies. We characterised the environment of IC 4200 by looking for extragalactic objects within 100 arcmin (∼1.6 Mpc at this redshift) and 300 km/s from the galaxy; for this search we used the Nasa Extragalactic Databas ...
Three Binary Millisecond Pulsars in NGC 6266
... for pulsars in the system of southern GCs using the Parkes 64 m radio telescope that commenced in 2000. It exploits the high sensitivity of the central beam of the Parkes multibeam receiver (Staveley-Smith et al. 1996), the efficiency of a modern data acquisition system (e.g., Manchester et al. 2001; ...
... for pulsars in the system of southern GCs using the Parkes 64 m radio telescope that commenced in 2000. It exploits the high sensitivity of the central beam of the Parkes multibeam receiver (Staveley-Smith et al. 1996), the efficiency of a modern data acquisition system (e.g., Manchester et al. 2001; ...
Differential rotation on both components of the pre-main
... are therefore found to have rates of differential rotation similar to those of the same spectraltype main-sequence single stars. The results for HD 155555 are therefore in contrast to those found in other, more evolved, binary systems where negligible or weak differential rotation has been discovere ...
... are therefore found to have rates of differential rotation similar to those of the same spectraltype main-sequence single stars. The results for HD 155555 are therefore in contrast to those found in other, more evolved, binary systems where negligible or weak differential rotation has been discovere ...
Radio pulsars
... • New population of high-B pulsars and new SNR associations • Globular clusters contain many millisecond pulsars • Precision timing of binary millisecond pulsars measures many properties of binary stars and tests general relativity. • Discovery of highly relativistic binary pulsar significantly incr ...
... • New population of high-B pulsars and new SNR associations • Globular clusters contain many millisecond pulsars • Precision timing of binary millisecond pulsars measures many properties of binary stars and tests general relativity. • Discovery of highly relativistic binary pulsar significantly incr ...
IAC_L3_thickdisk
... the disk, e.g. via Jeans equation. Is there more matter in the disk that we can account for from census of visible objects ? The tracer sample must be in equilibrium so the stars need to be older than a few Gyr. The last few estimates have used K dwarfs and K giants - probably OK but they do include ...
... the disk, e.g. via Jeans equation. Is there more matter in the disk that we can account for from census of visible objects ? The tracer sample must be in equilibrium so the stars need to be older than a few Gyr. The last few estimates have used K dwarfs and K giants - probably OK but they do include ...
8) consequence of the new theory about the
... 4.2 THE UNIVERSE CYCLE; FUTURE DEVELOPMENTS IN THE UNIVERSE AS FROM THE PRESENT: For the next aproximate 400 – 600 billion years the universe will still expand to a sphere with a radius of about 8 - 10 billion light years. This expansion, already decelerating from the current approximate 650 km/sec ...
... 4.2 THE UNIVERSE CYCLE; FUTURE DEVELOPMENTS IN THE UNIVERSE AS FROM THE PRESENT: For the next aproximate 400 – 600 billion years the universe will still expand to a sphere with a radius of about 8 - 10 billion light years. This expansion, already decelerating from the current approximate 650 km/sec ...
Accreting magnetars: a new type of high-mass X-ray binaries? P. Reig,
... Prior to the determination of the spin period, we converted the arrival times to the Solar system barycentre. Then we generate a light curve in the 0.2–12 keV energy range with a bin size of 10 s. The last ∼2300 s of the light curve were affected by high background. After removing this part the tota ...
... Prior to the determination of the spin period, we converted the arrival times to the Solar system barycentre. Then we generate a light curve in the 0.2–12 keV energy range with a bin size of 10 s. The last ∼2300 s of the light curve were affected by high background. After removing this part the tota ...
PH607 – Galaxies
... Hubble Deep Field: Probably the deepest image ever taken was by the HST over about 150 consecutive orbits (about 10 days) from December 18 through 30, 1995 on a single piece of sky located at 12h 36m 49.4000s +62d 12' 58.000" (near the Big Dipper). ...
... Hubble Deep Field: Probably the deepest image ever taken was by the HST over about 150 consecutive orbits (about 10 days) from December 18 through 30, 1995 on a single piece of sky located at 12h 36m 49.4000s +62d 12' 58.000" (near the Big Dipper). ...
Article PDF - IOPscience
... Since the phase offsets between RR Lyrae griz light curves are smaller than 1% (Sesar et al. 2010), we adopt the VanderPlas & Ivezić (2015) shared-phase model when calculating the multiband periodogram (i.e., we set gatspy parameters Nbase = 1 and Nband = 0; see Section5 of VanderPlas & Ivezić 2015 ...
... Since the phase offsets between RR Lyrae griz light curves are smaller than 1% (Sesar et al. 2010), we adopt the VanderPlas & Ivezić (2015) shared-phase model when calculating the multiband periodogram (i.e., we set gatspy parameters Nbase = 1 and Nband = 0; see Section5 of VanderPlas & Ivezić 2015 ...
Untitled - METU Astrophysics Home Page
... X-ray luminosity emitted from accreting X-ray binaries result from the conversion of the gravitational energy of accreted matter into kinetic energy. As the matter falls down onto the large gravitational potential well of the compact object, it gains tremendous acceleration. However, when it meets w ...
... X-ray luminosity emitted from accreting X-ray binaries result from the conversion of the gravitational energy of accreted matter into kinetic energy. As the matter falls down onto the large gravitational potential well of the compact object, it gains tremendous acceleration. However, when it meets w ...
black holes can play a constructive role as well
... extract those objects detected in the F225W image and at least one other filter. Cross correlation of the ACS and WFC3 object positions required a transformation between the ACS F606W and WFC3 F814W coordinate grids, which was calculated using the iraf task geomap and the positions of 37 point sourc ...
... extract those objects detected in the F225W image and at least one other filter. Cross correlation of the ACS and WFC3 object positions required a transformation between the ACS F606W and WFC3 F814W coordinate grids, which was calculated using the iraf task geomap and the positions of 37 point sourc ...
$doc.title
... Ken Nagamine, John O’Meara, Paolo Padoan, Pascal Paschos, Gabe Rockefeller, Frank Timmes, Matthew Turk, David Tytler, Dan Whalen, and John Wise. Many thanks go to Greg Bryan for useful discussions, for writing Enzo, and for all of the technical and scientific support that he has given me over the ye ...
... Ken Nagamine, John O’Meara, Paolo Padoan, Pascal Paschos, Gabe Rockefeller, Frank Timmes, Matthew Turk, David Tytler, Dan Whalen, and John Wise. Many thanks go to Greg Bryan for useful discussions, for writing Enzo, and for all of the technical and scientific support that he has given me over the ye ...
Analysis of Stellar Activity and Orbital Dynamics in Extrasolar
... Numerical simulations show that the giant impact phase can last up to 100 million years if Jupiter and Saturn were initially on circular orbits as proposed by the Nice model. Additionally, circular initial orbits for the giant planets enable the terrestrial planets to accrete waterrich material from ...
... Numerical simulations show that the giant impact phase can last up to 100 million years if Jupiter and Saturn were initially on circular orbits as proposed by the Nice model. Additionally, circular initial orbits for the giant planets enable the terrestrial planets to accrete waterrich material from ...
Variable Star Section Circular - Number 75
... This Circular, number 75, has been issued out of sequence - numbers 73 and 74 will follow soon after, at the end of February. This might create problems if your subscription has nearly run out. The number of Circulars that you still have to come is indicated by the part of the serial number followin ...
... This Circular, number 75, has been issued out of sequence - numbers 73 and 74 will follow soon after, at the end of February. This might create problems if your subscription has nearly run out. The number of Circulars that you still have to come is indicated by the part of the serial number followin ...
Transparencies - Rencontres de Moriond
... Confusion w HeI/HI emission line stars (≈ LBV or WR star) ? • No such star closer than 1.2" • Soft spectrum of W-R stars : cannot penetrate through the deep obscuration Colliding winds of binary system including a W-R star ? • Harder spectrum • Variability on days to years rather than hours Low mass ...
... Confusion w HeI/HI emission line stars (≈ LBV or WR star) ? • No such star closer than 1.2" • Soft spectrum of W-R stars : cannot penetrate through the deep obscuration Colliding winds of binary system including a W-R star ? • Harder spectrum • Variability on days to years rather than hours Low mass ...
The thin disk
... Later type galaxies mostly have near-exponential bulges, rather than r1/4 bulges - hint that their bulges are not merger products - more likely generated by disk instability (eg Balcells et al 2002) Boxy bulges, as in our Galaxy, are associated with bars eg Bureau & KF 1999 - believed to come from ...
... Later type galaxies mostly have near-exponential bulges, rather than r1/4 bulges - hint that their bulges are not merger products - more likely generated by disk instability (eg Balcells et al 2002) Boxy bulges, as in our Galaxy, are associated with bars eg Bureau & KF 1999 - believed to come from ...
Spiral arm structures revealed in the M31 galaxy
... Striking regularities are found in the northwestern arm of the M31 galaxy. Star complexes located in this arm are spaced 1.2 kpc apart and have similar sizes of about 0.6 kpc. This pattern is observed within the arm region where Beck et al. (1989) detected a strong regular magnetic field with the wa ...
... Striking regularities are found in the northwestern arm of the M31 galaxy. Star complexes located in this arm are spaced 1.2 kpc apart and have similar sizes of about 0.6 kpc. This pattern is observed within the arm region where Beck et al. (1989) detected a strong regular magnetic field with the wa ...
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.