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The University of Sydney Page
... Very low mass stars Very low mass stars (mass less than about 0.4 solar masses) are different in one important respect from heavier stars: their interiors are fully convective. The fused helium is stirred through the whole star, so it has the whole of its hydrogen mass to prolong its stay on the ma ...
... Very low mass stars Very low mass stars (mass less than about 0.4 solar masses) are different in one important respect from heavier stars: their interiors are fully convective. The fused helium is stirred through the whole star, so it has the whole of its hydrogen mass to prolong its stay on the ma ...
Comparison of low- and high-mass star formation
... to competitive accretion. One may plausibly identify the dense filament in the early phase and the dense region at the bottom of the global gravitational potential well in the late phase as a McKee–Tan core (McKee & Tan 2003). However, the “cores” so identified are transient objects that are not in ...
... to competitive accretion. One may plausibly identify the dense filament in the early phase and the dense region at the bottom of the global gravitational potential well in the late phase as a McKee–Tan core (McKee & Tan 2003). However, the “cores” so identified are transient objects that are not in ...
The connection between stellar activity cycles and magnetic field
... the angular rotational frequency, ωcyc /Ω, is plotted against inverse Rossby number, Ro−1 = τc /Prot . Here, τc and Prot are the convective turnover time and rotation period respectively. These authors called these branches the inactive, active and superactive branches. It is thought that the differ ...
... the angular rotational frequency, ωcyc /Ω, is plotted against inverse Rossby number, Ro−1 = τc /Prot . Here, τc and Prot are the convective turnover time and rotation period respectively. These authors called these branches the inactive, active and superactive branches. It is thought that the differ ...
magnitude handout
... only because it is a mere 2.6 parsecs away. Were Sirius located at 10 parsecs, it would haves an absolute magnitude of 1.5, a full three magnitudes fainter. If Sirius were actually at 10 parsecs, then it would be outclassed by over 20 other stars in our night sky. On the other hand the star Betelgeu ...
... only because it is a mere 2.6 parsecs away. Were Sirius located at 10 parsecs, it would haves an absolute magnitude of 1.5, a full three magnitudes fainter. If Sirius were actually at 10 parsecs, then it would be outclassed by over 20 other stars in our night sky. On the other hand the star Betelgeu ...
Distances in Cosmology One of the most basic measurements that
... am I? How about that building? How far is it to my school or travel destination? In fact, throughout the history of astronomy, distance measurements have played a key and often surprising role. In this lecture, we will first discuss direct observations, then some of the different measures of distanc ...
... am I? How about that building? How far is it to my school or travel destination? In fact, throughout the history of astronomy, distance measurements have played a key and often surprising role. In this lecture, we will first discuss direct observations, then some of the different measures of distanc ...
Night Sky Observations
... Greenwich Mean Time / Universal Time: The local time at the 0 meridian passing through Greenwich, England; it is the same everywhere, anytime! South African Standard Time: GMT +2 hours. If the GMT is 15h00, SAST will be 17h00. Constellation: A pattern of stars connected with imaginary lines to form ...
... Greenwich Mean Time / Universal Time: The local time at the 0 meridian passing through Greenwich, England; it is the same everywhere, anytime! South African Standard Time: GMT +2 hours. If the GMT is 15h00, SAST will be 17h00. Constellation: A pattern of stars connected with imaginary lines to form ...
TMT Scientific Information Brochure
... When construction is completed in 2018, the TMT will begin driving new discoveries with other next-generation observatories such as the Atacama Large Millimeter/submillimeter Array and the James Webb Space Telescope. ...
... When construction is completed in 2018, the TMT will begin driving new discoveries with other next-generation observatories such as the Atacama Large Millimeter/submillimeter Array and the James Webb Space Telescope. ...
Galaxies have different sizes and shapes.
... The disk of the Milky Way measures The Milky Way is about 100,000 light-years in diameter. more than 100,000 light-years in diameter. The bulge of densely packed stars at the center is located about 26,000 light-years from the Sun. A large but very faint layer of stars surrounds the disk and bulge. ...
... The disk of the Milky Way measures The Milky Way is about 100,000 light-years in diameter. more than 100,000 light-years in diameter. The bulge of densely packed stars at the center is located about 26,000 light-years from the Sun. A large but very faint layer of stars surrounds the disk and bulge. ...
Primary and secondary eclipse spectroscopy with JWST: exploring
... Methods. We used analytic formula and model data for both the astrophysical scene and the instrument to plot S /N contour maps, while indicating how the S /N scales with the fixed parameters. We systematically compare stellar photon noise-only plots with plots that include detailed instrumental and ...
... Methods. We used analytic formula and model data for both the astrophysical scene and the instrument to plot S /N contour maps, while indicating how the S /N scales with the fixed parameters. We systematically compare stellar photon noise-only plots with plots that include detailed instrumental and ...
PH607lec10-4gal2
... This arrangement produces a spiral density wave: spiral arms are caused by a density perturbation that moves along at a speed different from the speed of the objects within it. The density wave resists the spiral’s tendency to wind up and causes a rigidly rotating spiral pattern Properties of spiral ...
... This arrangement produces a spiral density wave: spiral arms are caused by a density perturbation that moves along at a speed different from the speed of the objects within it. The density wave resists the spiral’s tendency to wind up and causes a rigidly rotating spiral pattern Properties of spiral ...
Oxygen and Neon Abundances of B-Type Stars in Comparison with
... (1998) via the SIMBAD database. The resulting Teff and logg are summarized in table 1. Their typical errors may be estimated as 3% in Teff and 0.2 dex in logg for the present case of mid-through-late B stars, according to Napiwotzki, Schönberner, and Wenske (1993; cf. their section 5). The model ...
... (1998) via the SIMBAD database. The resulting Teff and logg are summarized in table 1. Their typical errors may be estimated as 3% in Teff and 0.2 dex in logg for the present case of mid-through-late B stars, according to Napiwotzki, Schönberner, and Wenske (1993; cf. their section 5). The model ...
A Digital Spectral Classification Atlas
... autonomy of the system as well as ensuring that different observers will classify stars on the same system. When the MK system was first defined, it was based on photographic spectra in the blue-violet part of the spectrum. This was done by necessity, as scientific photographic emulsions in the 1940 ...
... autonomy of the system as well as ensuring that different observers will classify stars on the same system. When the MK system was first defined, it was based on photographic spectra in the blue-violet part of the spectrum. This was done by necessity, as scientific photographic emulsions in the 1940 ...
Life as a Low Mass Red Giant
... • As cluster ages, most massive stars run out of core Hydrogen first, moving to Red Giant stage: The point where stars are just leaving the Main Sequence is called "main sequence turnoff" point. http://www.astro.ubc.ca/~scharein/a311/Sim.html The age of a cluster is just the main sequence lifetime o ...
... • As cluster ages, most massive stars run out of core Hydrogen first, moving to Red Giant stage: The point where stars are just leaving the Main Sequence is called "main sequence turnoff" point. http://www.astro.ubc.ca/~scharein/a311/Sim.html The age of a cluster is just the main sequence lifetime o ...
Chapter 2 Surveying the stars 2.1 Star magnitudes
... The brightness of a star in the night sky depends on the intensity of the star’s light at the Earth which is the light energy per second per unit surface area received from the star at normal incidence on a surface. The intensity of sunlight at the Earth’s surface is about 1400 W m−2. In comparison, ...
... The brightness of a star in the night sky depends on the intensity of the star’s light at the Earth which is the light energy per second per unit surface area received from the star at normal incidence on a surface. The intensity of sunlight at the Earth’s surface is about 1400 W m−2. In comparison, ...
The new Basel high-latitude field star survey of the Galaxy
... parameters, we here explore some of the special conditions prevailing in the transition region from high to low latitudes approaching the Galactic bulge, such as interstellar reddening, preponderant sampling of giants, and possible large-scale radial metallicity gradients. We show that the data are ...
... parameters, we here explore some of the special conditions prevailing in the transition region from high to low latitudes approaching the Galactic bulge, such as interstellar reddening, preponderant sampling of giants, and possible large-scale radial metallicity gradients. We show that the data are ...
W The X-Ray Universe X-ray images of the Universe are
... nuclei of galaxies, and hot gas in intergalactic space. The X rays detected by X-ray astronomers, like those put to use in industry, medicine, and laboratory research, must be produced by high-energy particles. It is not surprising, then, that an X-ray image of the sky can look markedly different fr ...
... nuclei of galaxies, and hot gas in intergalactic space. The X rays detected by X-ray astronomers, like those put to use in industry, medicine, and laboratory research, must be produced by high-energy particles. It is not surprising, then, that an X-ray image of the sky can look markedly different fr ...
July - Rose City Astronomers
... with as little equipment as a binocular and a Field Chart scaled making visual magnitude estimates using this chart. for binoculars that has been created for this purpose by the This same chart can also be used that very evening for making real time observations with binoculars and small telescopes. ...
... with as little equipment as a binocular and a Field Chart scaled making visual magnitude estimates using this chart. for binoculars that has been created for this purpose by the This same chart can also be used that very evening for making real time observations with binoculars and small telescopes. ...
Carbon, nitrogen, oxygen and lithium abundances of six
... whereas the Sc abundance has been determined from other lines (Paper I). The oxygen abundance was then derived by fitting the observed [OI] line with the line computed with different oxygen abundance values; let us note that the [OI] and the nearby ScII lines form roughly in the same atmospheric lay ...
... whereas the Sc abundance has been determined from other lines (Paper I). The oxygen abundance was then derived by fitting the observed [OI] line with the line computed with different oxygen abundance values; let us note that the [OI] and the nearby ScII lines form roughly in the same atmospheric lay ...
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.