Astronomy Timeline
... 130 B.C. - Greek astronomer Hipparchus develops the first accurate star map and star catalogue, and a reliable method to predict solar eclipses 46 B.C. - Julius Caesar, after consulting the astronomer Sosigenes of Alexandria, introduces the Julian Calendar, a regular year of 365 days divided into 12 ...
... 130 B.C. - Greek astronomer Hipparchus develops the first accurate star map and star catalogue, and a reliable method to predict solar eclipses 46 B.C. - Julius Caesar, after consulting the astronomer Sosigenes of Alexandria, introduces the Julian Calendar, a regular year of 365 days divided into 12 ...
Carbon, nitrogen, oxygen and lithium abundances of six
... Abstract. Carbon, nitrogen and oxygen abundances were derived from high-resolution spectra of 6 cool supergiants of the Small Magellanic Cloud. Oxygen-to-iron ratios (mean value [O/Fe] ≈–0.18 dex) are found to be similar to those found in young objects in the LMC and the Galaxy. This result is discu ...
... Abstract. Carbon, nitrogen and oxygen abundances were derived from high-resolution spectra of 6 cool supergiants of the Small Magellanic Cloud. Oxygen-to-iron ratios (mean value [O/Fe] ≈–0.18 dex) are found to be similar to those found in young objects in the LMC and the Galaxy. This result is discu ...
Discovery of extremely lead-rich subdwarfs: does heavy metal signal
... Hot subdwarfs represent a group of low-mass helium-burning stars formed through binarystar interactions and include some of the most chemically peculiar stars in the Galaxy. Stellar evolution theory suggests that they should have helium-rich atmospheres but, because radiation causes hydrogen to diff ...
... Hot subdwarfs represent a group of low-mass helium-burning stars formed through binarystar interactions and include some of the most chemically peculiar stars in the Galaxy. Stellar evolution theory suggests that they should have helium-rich atmospheres but, because radiation causes hydrogen to diff ...
Nebulae.The Lagoon and Dumbbell Nebulae
... Dark nebulae block light because of their high density. They can be seen on the background of the Milky Way or other nebulae. ...
... Dark nebulae block light because of their high density. They can be seen on the background of the Milky Way or other nebulae. ...
![Module 4.1 - The Scale of the Universe [slide 1] We now turn to](http://s1.studyres.com/store/data/002846843_1-9e0ec9d1a2abbbab3c0d406694bfc4e2-300x300.png)
Module 4.1 - The Scale of the Universe [slide 1] We now turn to
... So the method by itself is safe, the problem is that, these are very small angles, and the current state of the art is that we can measure distances using parallaxes to about one kiloparsec out, more or less, and that's well within our own galaxy, never mind external galaxies. [slide 3] The next one ...
... So the method by itself is safe, the problem is that, these are very small angles, and the current state of the art is that we can measure distances using parallaxes to about one kiloparsec out, more or less, and that's well within our own galaxy, never mind external galaxies. [slide 3] The next one ...
Rotation Periods and Relative Ages of Solar-Type Stars
... of certain metals in a star’s photosphere, also serves as an indicator of age. For example, since the Sun is still burning hydrogen in its core, it is too “young” to produce heavy metals. Metals like calcium, iron, lithium, and magnesium, observed on the stellar surface, can be assumed to be primord ...
... of certain metals in a star’s photosphere, also serves as an indicator of age. For example, since the Sun is still burning hydrogen in its core, it is too “young” to produce heavy metals. Metals like calcium, iron, lithium, and magnesium, observed on the stellar surface, can be assumed to be primord ...
1 Astrobiologically Interesting Stars within 10
... may have outlasted their usefulness as abodes of life, if the luminosity increase sustained from zero age to their present evolutionary status surpasses the capability of the planetary thermo-regulating carbonate-silicate cycle. This situation is dependent upon planetary location inside the CHZ, yet ...
... may have outlasted their usefulness as abodes of life, if the luminosity increase sustained from zero age to their present evolutionary status surpasses the capability of the planetary thermo-regulating carbonate-silicate cycle. This situation is dependent upon planetary location inside the CHZ, yet ...
A Zoo of Galaxies - Cambridge University Press
... in order to reveal its size and mass. Hubble is most famous for a discovery which revolutionised extragalactic astronomy in its ability to provide a relatively quick and easy way to make these distance estimates. In 1929, Edwin Hubble used a sample of just 24 nearby galaxies to make this discovery. ...
... in order to reveal its size and mass. Hubble is most famous for a discovery which revolutionised extragalactic astronomy in its ability to provide a relatively quick and easy way to make these distance estimates. In 1929, Edwin Hubble used a sample of just 24 nearby galaxies to make this discovery. ...
Magnitude Scales and Photometric Systems
... the primary standards. Later lists comprising more stars and fainter stars but based on the primary standards are called secondary standards. However, in the case of all photometric systems, recently published secondary standards effectively redefine the standard system because they tend to be more ...
... the primary standards. Later lists comprising more stars and fainter stars but based on the primary standards are called secondary standards. However, in the case of all photometric systems, recently published secondary standards effectively redefine the standard system because they tend to be more ...
Ursa Major
Ursa Major /ˈɜrsə ˈmeɪdʒər/ (also known as the Great Bear and Charles' Wain) is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by Ptolemy (second century AD), it remains one of the 88 modern constellations. It can be visible throughout the year in most of the northern hemisphere. Its name, Latin for ""the greater (or larger) she-bear"", stands as a reference to and in direct contrast with Ursa Minor, ""the smaller she-bear"", with which it is frequently associated in mythology and amateur astronomy. The constellation's most recognizable asterism, a group of seven relatively bright stars commonly known as the ""Big Dipper"", ""the Wagon"" or ""the Plough"" (among others), both mimicks the shape of the lesser bear (the ""Little Dipper"") and is commonly used as a navigational pointer towards the current northern pole star, Polaris in Ursa Minor. The Big Dipper and the constellation as a whole have mythological significance in numerous world cultures, usually as a symbol of the north.The third largest constellation in the sky, Ursa Major is home to many deep-sky objects including seven Messier objects, four other NGC objects and I Zwicky 18, the youngest known galaxy in the visible universe.