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Annual Report 2010 - Koninklijke Sterrenwacht van België
... We maintain presently six high-quality clocks for participation in two international timescales: the International Atomic Time (TAI) and the International GNSS Service Timescale (IGST). The present requirement for the clock precision and stability is at the level of the nanosecond over one day, whic ...
... We maintain presently six high-quality clocks for participation in two international timescales: the International Atomic Time (TAI) and the International GNSS Service Timescale (IGST). The present requirement for the clock precision and stability is at the level of the nanosecond over one day, whic ...
The physics of star formation
... Stars are the fundamental units of luminous matter in the universe, and they are responsible, directly or indirectly, for most of what we see when we observe it. They also serve as our primary tracers of the structure and evolution of the universe and its contents. Consequently, it is of central imp ...
... Stars are the fundamental units of luminous matter in the universe, and they are responsible, directly or indirectly, for most of what we see when we observe it. They also serve as our primary tracers of the structure and evolution of the universe and its contents. Consequently, it is of central imp ...
Shearer et al Observations of Fermi Pulsars 2009-10
... This programme was intended to carryout CCD imaging observations of pulsars detected by the Fermi telescope. These would then be followed by observations with one of three high time resolution cameras which would be able to make definitive observations on the basis of timing. Under this round of the ...
... This programme was intended to carryout CCD imaging observations of pulsars detected by the Fermi telescope. These would then be followed by observations with one of three high time resolution cameras which would be able to make definitive observations on the basis of timing. Under this round of the ...
WAS THE SUN BORN IN A MASSIVE CLUSTER?
... stars, on the basis that, in a larger cluster, close encounters between the Sun and other stars would have truncated the outer solar system or excited the outer planets into eccentric orbits. However, this dynamical limit is in tension with meteoritic evidence that the solar system was exposed to a ...
... stars, on the basis that, in a larger cluster, close encounters between the Sun and other stars would have truncated the outer solar system or excited the outer planets into eccentric orbits. However, this dynamical limit is in tension with meteoritic evidence that the solar system was exposed to a ...
The redshift of extragalactic nebulae
... nebulae. He started from the idea that the redshift correlated with the famous Einstein effect. It appeared, however, that it was not possible in this way to uncover rational relationships. E. HUBBLE then tried to correlate the redshift with the distance of different nebulae. This experiment has, as ...
... nebulae. He started from the idea that the redshift correlated with the famous Einstein effect. It appeared, however, that it was not possible in this way to uncover rational relationships. E. HUBBLE then tried to correlate the redshift with the distance of different nebulae. This experiment has, as ...
Characterization and Subtraction of Well
... ghost is caused by a reflection between the filter and the window at the entrance aperture of the NIC2 dewar. The integrated brightness of the ghost is 8 mag fainter than that of the star. The ghost cannot be completely subtracted from the field unless the reference PSF is at the same location as th ...
... ghost is caused by a reflection between the filter and the window at the entrance aperture of the NIC2 dewar. The integrated brightness of the ghost is 8 mag fainter than that of the star. The ghost cannot be completely subtracted from the field unless the reference PSF is at the same location as th ...
IAC_L2_thindisk
... • the thick disk stars are all old (> 10 Gyr) and have abundances between about -0.3 to -1.2, with a metal-weak tail extending down to about -2.0. • the thick disk stars form an -enhanced sequence in the [ /Fe] vs [Fe/H]. Because of operational difficulties in assigning individual stars kinematica ...
... • the thick disk stars are all old (> 10 Gyr) and have abundances between about -0.3 to -1.2, with a metal-weak tail extending down to about -2.0. • the thick disk stars form an -enhanced sequence in the [ /Fe] vs [Fe/H]. Because of operational difficulties in assigning individual stars kinematica ...
Paper by Bessell, Castelli and Plez on Model atmospheres
... Another technique is to use maps of the galactic distribution of dust, such as those of Fitzgerald (1986) and Burnstein & Heiles (1982) combined with estimate of the distance of the star from a trigonometric parallax or spectral/luminosity class. However, it is generally believed that within 100 pc ...
... Another technique is to use maps of the galactic distribution of dust, such as those of Fitzgerald (1986) and Burnstein & Heiles (1982) combined with estimate of the distance of the star from a trigonometric parallax or spectral/luminosity class. However, it is generally believed that within 100 pc ...
Sec 30.1 - Highland High School
... After reasoning there were globular clusters orbiting the center of the Milky Way, astronomers then used RR Lyrae variables to determine the distances to them. ...
... After reasoning there were globular clusters orbiting the center of the Milky Way, astronomers then used RR Lyrae variables to determine the distances to them. ...
Present-day cosmic abundances - Dr. Karl Remeis
... An ideal alternative to find a reference for the chemical composition of cosmic matter are normal unevolved early B-type stars of ∼8-18 M⊙ , which can provide simultaneously temporal (present-day) and local (birth place) information on chemical abundances. They can be observed not only in the solar ...
... An ideal alternative to find a reference for the chemical composition of cosmic matter are normal unevolved early B-type stars of ∼8-18 M⊙ , which can provide simultaneously temporal (present-day) and local (birth place) information on chemical abundances. They can be observed not only in the solar ...
Note - HKU Physics
... words, every microscopically large but macroscopically small region is very close to and hence can be well approximated by a region in thermodynamic equilibrium. Thus, it makes sense to talk about thermodynamic variables such as temperature, density and pressure in these regions. This approximation ...
... words, every microscopically large but macroscopically small region is very close to and hence can be well approximated by a region in thermodynamic equilibrium. Thus, it makes sense to talk about thermodynamic variables such as temperature, density and pressure in these regions. This approximation ...
Carbon, nitrogen and oxygen abundances in
... profiles. Therefore, in most cases the W values were measured by direct integration. We checked for possible blending of the lines using the data base VALD (Kupka et al. 1999; Heiter et al. 2008) and predicted W values for models based on parameters Teff and log g from Paper II. Only those lines wer ...
... profiles. Therefore, in most cases the W values were measured by direct integration. We checked for possible blending of the lines using the data base VALD (Kupka et al. 1999; Heiter et al. 2008) and predicted W values for models based on parameters Teff and log g from Paper II. Only those lines wer ...
Attitude and Interlock Angle Estimation using Split-Field-of
... attitude sensor used. For example, the attitude estimate accuracy that can be achieved with the Sun sensors is approximately 0.015 degrees for two-axis attitude estimation (direction of the Sun in body and inertial frame) with the best available instruments; however, for starcamera this number for t ...
... attitude sensor used. For example, the attitude estimate accuracy that can be achieved with the Sun sensors is approximately 0.015 degrees for two-axis attitude estimation (direction of the Sun in body and inertial frame) with the best available instruments; however, for starcamera this number for t ...
Studies of molecular clouds at the Galactic centre Roland Karlsson DECLINATION (B1950)
... PAPER I: I contributed to the preparation of the proposal to NRAO, as well as the full procedure for preparing and performing the observations, together with Aage Sandqvist, John Whiteoak and Frank Gardner. The post-observational calibration of the data was made at the VLA together with Aage Sandqvi ...
... PAPER I: I contributed to the preparation of the proposal to NRAO, as well as the full procedure for preparing and performing the observations, together with Aage Sandqvist, John Whiteoak and Frank Gardner. The post-observational calibration of the data was made at the VLA together with Aage Sandqvi ...
The mass-loss return from evolved stars to the Large Magellanic Cloud
... The study of Milky Way AGB stars is inhibited by the presence of substantial interstellar extinction, and large uncertainties in distance determinations. The Large Magellanic Cloud (LMC) offers the combination of proximity (∼50 kpc; van Leeuwen et al. 2007), low line-of-sight extinction (E(B − V) ∼ 0 ...
... The study of Milky Way AGB stars is inhibited by the presence of substantial interstellar extinction, and large uncertainties in distance determinations. The Large Magellanic Cloud (LMC) offers the combination of proximity (∼50 kpc; van Leeuwen et al. 2007), low line-of-sight extinction (E(B − V) ∼ 0 ...
Full Text - Departement Natuurkunde en Sterrenkunde
... Strömgren photometric system . . . . . . . . . . . . . . . . . . . . . 165 ...
... Strömgren photometric system . . . . . . . . . . . . . . . . . . . . . 165 ...
1 Introduction - Wiley-VCH
... Their kinematic is characterized by a more or less significant rotation. They are generally referred to as late-type systems. In addition to these two families, there exists an intermediate class of objects. The lenticular galaxies (S0) are characterized by a flat disk without any spiral structure, ...
... Their kinematic is characterized by a more or less significant rotation. They are generally referred to as late-type systems. In addition to these two families, there exists an intermediate class of objects. The lenticular galaxies (S0) are characterized by a flat disk without any spiral structure, ...
Parallax
... in space. The major assumption needed is that each planet follows a repeatable path through space, so after a whole number of orbital periods it is back to the same place. So after one Mars’ period, it would be at the same place while the Earth would be somewhere else in its orbit. Repeating this ob ...
... in space. The major assumption needed is that each planet follows a repeatable path through space, so after a whole number of orbital periods it is back to the same place. So after one Mars’ period, it would be at the same place while the Earth would be somewhere else in its orbit. Repeating this ob ...
Hipparcos
![](https://commons.wikimedia.org/wiki/Special:FilePath/Hipparcos-testing-estec.jpg?width=300)
Hipparcos was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial objects on the sky. This permitted the accurate determination of proper motions and parallaxes of stars, allowing a determination of their distance and tangential velocity. When combined with radial-velocity measurements from spectroscopy, this pinpointed all six quantities needed to determine the motion of stars. The resulting Hipparcos Catalogue, a high-precision catalogue of more than 118,200 stars, was published in 1997. The lower-precision Tycho Catalogue of more than a million stars was published at the same time, while the enhanced Tycho-2 Catalogue of 2.5 million stars was published in 2000. Hipparcos ' follow-up mission, Gaia, was launched in 2013.The word ""Hipparcos"" is an acronym for High precision parallax collecting satellite and also a reference to the ancient Greek astronomer Hipparchus of Nicaea, who is noted for applications of trigonometry to astronomy and his discovery of the precession of the equinoxes.