Stellar Masses
... stably. Objects with masses slightly below this limit are called brown dwarfs, and are ‘star like’ in the sense that nuclear burning of deuterium occurs in their core. Below a mass of 0.015M⊙ (roughly 16 times the mass of Jupiter) not even deuterium burning can occur, and these objects are perhaps b ...
... stably. Objects with masses slightly below this limit are called brown dwarfs, and are ‘star like’ in the sense that nuclear burning of deuterium occurs in their core. Below a mass of 0.015M⊙ (roughly 16 times the mass of Jupiter) not even deuterium burning can occur, and these objects are perhaps b ...
Is Draco II one of the faintest dwarf galaxies? First study from Keck
... hofer A band in the range 7595–7630 A in order to perform small telluric corrections (Martin et al. 2014). The signal to noise per pixel (S/N) of the reduced spectra in the Ca triplet region is typical 30/8 at iP1 = 18.0/20.0. For a cold stellar system like Dra II, it is particularly important to as ...
... hofer A band in the range 7595–7630 A in order to perform small telluric corrections (Martin et al. 2014). The signal to noise per pixel (S/N) of the reduced spectra in the Ca triplet region is typical 30/8 at iP1 = 18.0/20.0. For a cold stellar system like Dra II, it is particularly important to as ...
129 DYNAMICAL STREAMS IN THE SOLAR NEIGHBOURHOOD B
... alone is not sufficient to create the observed streams. Nevertheless, De Simone et al. (2004) have shown that the structure of the local distribution function could well be due to a lumpy potential related to the presence of strong transient spiral waves. Besides those simulations, a recent model of ...
... alone is not sufficient to create the observed streams. Nevertheless, De Simone et al. (2004) have shown that the structure of the local distribution function could well be due to a lumpy potential related to the presence of strong transient spiral waves. Besides those simulations, a recent model of ...
Herschel
... - New discs, mainly around K-type stars. • Flux levels similar to those of our EKB reached. • A large number of resolved discs (5 x previous). • “New class” of debris discs: - Excesses only at 160 µm: Very cold and faint discs, Tdust ≲ 30 K, that could be representative of a new physical regime. Mor ...
... - New discs, mainly around K-type stars. • Flux levels similar to those of our EKB reached. • A large number of resolved discs (5 x previous). • “New class” of debris discs: - Excesses only at 160 µm: Very cold and faint discs, Tdust ≲ 30 K, that could be representative of a new physical regime. Mor ...
Ch 11a (Measuring Stars 10-28-10)
... IV. Stellar sizes (radius) Luminosity is proportional to surface area (how large) x temperature (how hot): L= 4R2T4 If we can measure the Luminosity and the temperature of a star we can tell how large its ...
... IV. Stellar sizes (radius) Luminosity is proportional to surface area (how large) x temperature (how hot): L= 4R2T4 If we can measure the Luminosity and the temperature of a star we can tell how large its ...
5 Understanding stars and star ClUsters
... Electron orbital motions cause the spectral lines. Electrons are small particles with a negative charge that orbit the atomic nucleus. Electrons must always move in distinct orbit levels. If the electron moves to the next lower orbit it loses energy and spits out a light particle (photon) of a speci ...
... Electron orbital motions cause the spectral lines. Electrons are small particles with a negative charge that orbit the atomic nucleus. Electrons must always move in distinct orbit levels. If the electron moves to the next lower orbit it loses energy and spits out a light particle (photon) of a speci ...
$doc.title
... temperature-sensitive. Once it is mixed into stellar layers with temperatures exceeding 3 × 106 K, it is destroyed via proton captures to form helium. Its fragility makes Li an important diagnostic tool for stellar evolution (Rebolo, 1991), and also has a high significance in the determination of co ...
... temperature-sensitive. Once it is mixed into stellar layers with temperatures exceeding 3 × 106 K, it is destroyed via proton captures to form helium. Its fragility makes Li an important diagnostic tool for stellar evolution (Rebolo, 1991), and also has a high significance in the determination of co ...
Stellar Evolution
... The R and N stellar classifications corresponded to carbon stars and now have been merged into one classification designated C (although not the same as the original C stars, which were spectroscopic binaries). Many people however still use the R and N classification (including me) to describe carbo ...
... The R and N stellar classifications corresponded to carbon stars and now have been merged into one classification designated C (although not the same as the original C stars, which were spectroscopic binaries). Many people however still use the R and N classification (including me) to describe carbo ...
Atoms and Stars IST 3360 and IST 1990
... • Five visible planets Mercury, Venus, Mars, Jupiter, Saturn move with respect to stars o Uranus, Neptune, Pluto require telescope ...
... • Five visible planets Mercury, Venus, Mars, Jupiter, Saturn move with respect to stars o Uranus, Neptune, Pluto require telescope ...
Practice Exam for 3 rd Astronomy Exam
... only electron removed creating a positive hydrogen ion. HI is regular neutral hydrogen with no electrons removed. You cannot have HIII because that would mean that 2 electrons have been removed from hydrogen and hydrogen only has one electron. HII regions are the signature of a star forming region, ...
... only electron removed creating a positive hydrogen ion. HI is regular neutral hydrogen with no electrons removed. You cannot have HIII because that would mean that 2 electrons have been removed from hydrogen and hydrogen only has one electron. HII regions are the signature of a star forming region, ...
2 The Concept of “Spectral Classes”
... All stars including the standards are peculiar at some level. Hence, the most complicated part of any classification system is the array of spectral peculiarities, usually designated by a single letter or character. The descriptions of these attributes, P1P2P3P4, each of which has a value in the ran ...
... All stars including the standards are peculiar at some level. Hence, the most complicated part of any classification system is the array of spectral peculiarities, usually designated by a single letter or character. The descriptions of these attributes, P1P2P3P4, each of which has a value in the ran ...
3.2 Black body Radiation
... puts more energy into the sphere - it gets hotter. Eventually it starts to glow dimly. As you continue heating it the sphere glows first red, then orange, yellow then white hot. If you were able to keep heating it sufficiently it may even glow blue hot. This sphere approximates what physicists call ...
... puts more energy into the sphere - it gets hotter. Eventually it starts to glow dimly. As you continue heating it the sphere glows first red, then orange, yellow then white hot. If you were able to keep heating it sufficiently it may even glow blue hot. This sphere approximates what physicists call ...
The Sun
... – The brightness we observe for a star depends on both its luminosity and its distance. – Luminosity is measured in units of energy emitted per second, or watts. – The Sun’s luminosity is about 3.85 × 1026 W. ...
... – The brightness we observe for a star depends on both its luminosity and its distance. – Luminosity is measured in units of energy emitted per second, or watts. – The Sun’s luminosity is about 3.85 × 1026 W. ...
Photometry – I. “All sky”
... over 200 ! (see http://ulisse.pd.astro.it/ Astro/ADPS/). Early photometric systems – mainly broad-band – were used in a very general way; many systems were devised for rather specific applications (eg for the investigation of specific types of star such as hot stars, cool stars, etc). Some systems a ...
... over 200 ! (see http://ulisse.pd.astro.it/ Astro/ADPS/). Early photometric systems – mainly broad-band – were used in a very general way; many systems were devised for rather specific applications (eg for the investigation of specific types of star such as hot stars, cool stars, etc). Some systems a ...
Notes for Class 5, February 16
... • Five visible planets Mercury, Venus, Mars, Jupiter, Saturn move with respect to stars o Uranus, Neptune, Pluto require telescope ...
... • Five visible planets Mercury, Venus, Mars, Jupiter, Saturn move with respect to stars o Uranus, Neptune, Pluto require telescope ...
ES Chapter 30
... – The brightness we observe for a star depends on both its luminosity and its distance. – Luminosity is measured in units of energy emitted per second, or watts. – The Sun’s luminosity is about 3.85 × 1026 W. ...
... – The brightness we observe for a star depends on both its luminosity and its distance. – Luminosity is measured in units of energy emitted per second, or watts. – The Sun’s luminosity is about 3.85 × 1026 W. ...
lecture_1_mbu - X-ray and Observational Astronomy Group
... These are ultraviolet lines and can only be seen from space by satellite observatories. ...
... These are ultraviolet lines and can only be seen from space by satellite observatories. ...
Lecture 1 - X-ray and Observational Astronomy Group
... These are ultraviolet lines and can only be seen from space by satellite observatories. ...
... These are ultraviolet lines and can only be seen from space by satellite observatories. ...
Variable Stars – II. Pulsating stars
... In this case the star is unstable to pulsation and any small variation, will be reinforced – the pulsation will grow until the energy input by the κ-mechanism reaches a limit. The star will then be pulsating with a stable period and amplitude. Note that the partial ionization zones can be near the s ...
... In this case the star is unstable to pulsation and any small variation, will be reinforced – the pulsation will grow until the energy input by the κ-mechanism reaches a limit. The star will then be pulsating with a stable period and amplitude. Note that the partial ionization zones can be near the s ...
HD 140283: A Star in the Solar Neighborhood that Formed Shortly
... and V − I colors through polynomial fits to a sample of 791 single main-sequence stars with accurate BVI photometry and Hipparcos or USNO parallaxes of 40 mas or higher (d < 25 pc), which is provided online by I. N. Reid2. A correction for metallicity, estimated from each star’s position in B − V vs ...
... and V − I colors through polynomial fits to a sample of 791 single main-sequence stars with accurate BVI photometry and Hipparcos or USNO parallaxes of 40 mas or higher (d < 25 pc), which is provided online by I. N. Reid2. A correction for metallicity, estimated from each star’s position in B − V vs ...
Hertzsprung–Russell diagram - Wikipedia, the free encyclopedia
... types is a monotonic series ordered by stellar surface temperature. Modern observational versions of the chart replace spectral type by a color index (in diagrams made in the middle of the 20th Century, most often the B-V color) of the stars. This type of diagram is what is often called an observati ...
... types is a monotonic series ordered by stellar surface temperature. Modern observational versions of the chart replace spectral type by a color index (in diagrams made in the middle of the 20th Century, most often the B-V color) of the stars. This type of diagram is what is often called an observati ...
What is a white dwarf?
... Their name comes from the fact they are 'born' glowing whitehot with high temperatures (remember that the core of a normal star has a higher temperature than the surface of the star). ...
... Their name comes from the fact they are 'born' glowing whitehot with high temperatures (remember that the core of a normal star has a higher temperature than the surface of the star). ...
(Science 2012) Gal-Yam
... from theoretical models of massive cores exploding via the pair-instability process. A lower ejecta mass (M = 43 M⊙) has been proposed (18). In any case, there is no doubt that these explosions are produced by extremely massive stars, with the most massive exploding heavy-element cores known to date ...
... from theoretical models of massive cores exploding via the pair-instability process. A lower ejecta mass (M = 43 M⊙) has been proposed (18). In any case, there is no doubt that these explosions are produced by extremely massive stars, with the most massive exploding heavy-element cores known to date ...
Stellar classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Light from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with absorption lines. Each line indicates an ion of a certain chemical element, with the line strength indicating the abundance of that ion. The relative abundance of the different ions varies with the temperature of the photosphere. The spectral class of a star is a short code summarizing the ionization state, giving an objective measure of the photosphere's temperature and density.Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O, B, A, F, G, K, and M, a sequence from the hottest (O type) to the coolest (M type). Each letter class is then subdivided using a numeric digit with 0 being hottest and 9 being coolest (e.g. A8, A9, F0, F1 form a sequence from hotter to cooler). The sequence has been expanded with classes for other stars and star-like objects that do not fit in the classical system, such class D for white dwarfs and class C for carbon stars.In the MK system a luminosity class is added to the spectral class using Roman numerals. This is based on the width of certain absorption lines in the star's spectrum which vary with the density of the atmosphere and so distinguish giant stars from dwarfs. Luminosity class 0 or Ia+ stars for hypergiants, class I stars for supergiants, class II for bright giants, class III for regular giants, class IV for sub-giants, class V for main-sequence stars, class sd for sub-dwarfs, and class D for white dwarfs. The full spectral class for the Sun is then G2V, indicating a main-sequence star with a temperature around 5,800K.