Lecture 14
... • Astronomers noticed that stellar spectra showed many similarities. • Can stars be classified or grouped according to similarities in their spectra? • Draper Survey at Harvard (1886-1897): – Objective prism photography – Obtained spectra of >100,000 stars – Hired women as “computers” to analyze spe ...
... • Astronomers noticed that stellar spectra showed many similarities. • Can stars be classified or grouped according to similarities in their spectra? • Draper Survey at Harvard (1886-1897): – Objective prism photography – Obtained spectra of >100,000 stars – Hired women as “computers” to analyze spe ...
Explosion and remnants of massive stars
... The main physical parameters that determine the appearance of a supernova are: • the total kinetic energy imparted by the explosion into the envelope, • the structure (density profile and chemical composition) of the pre-supernova star, as well as the possible presence of circumstellar material lost ...
... The main physical parameters that determine the appearance of a supernova are: • the total kinetic energy imparted by the explosion into the envelope, • the structure (density profile and chemical composition) of the pre-supernova star, as well as the possible presence of circumstellar material lost ...
Talk
... WDMS for which repeat SDSS spectroscopic observations are available. - From the SDSS spectra we determine Sp of the companions, Teff, M, log(g) of the WDs, as well as distance estimates to the systems. Even though some of the stellar parameters obtained from our decomposing/fitting technique differ ...
... WDMS for which repeat SDSS spectroscopic observations are available. - From the SDSS spectra we determine Sp of the companions, Teff, M, log(g) of the WDs, as well as distance estimates to the systems. Even though some of the stellar parameters obtained from our decomposing/fitting technique differ ...
The Origin, Structure, and Evolution of the Stars
... make a beginning with the first question we must realize that the space between the stars interstellar space is not entirely empty scattered throughout the galaxy is a diffuse gas consisting primarily of hydrogen atoms that is concentrated frequently in clouds the interstellar gas is so rarefied tha ...
... make a beginning with the first question we must realize that the space between the stars interstellar space is not entirely empty scattered throughout the galaxy is a diffuse gas consisting primarily of hydrogen atoms that is concentrated frequently in clouds the interstellar gas is so rarefied tha ...
Separating Stars and Galaxies Based on Color
... If a high resolution spectrum is available for an object, star/galaxy classification is almost always trivial, as spectral features unique to stars or galaxies are easily identifiable. However, due to limitations in telescope time and current detector technology, we do not have a spectrum for each o ...
... If a high resolution spectrum is available for an object, star/galaxy classification is almost always trivial, as spectral features unique to stars or galaxies are easily identifiable. However, due to limitations in telescope time and current detector technology, we do not have a spectrum for each o ...
Killer Skies
... Plots stellar luminosities vs. surface temperatures (or spectral classes) to study correlations between luminosity and temperature. Also enables astronomers to sort the stars by their sizes. The diagram is named after its originators:Ejnar Hertzsprung in the Netherlands, and Henry Norris Russell in ...
... Plots stellar luminosities vs. surface temperatures (or spectral classes) to study correlations between luminosity and temperature. Also enables astronomers to sort the stars by their sizes. The diagram is named after its originators:Ejnar Hertzsprung in the Netherlands, and Henry Norris Russell in ...
Document
... • We can measure the temperature of a star relatively easily by its spectral type or color. If the distance is known, then we can measure its luminosity, and then compute its radius. Note, however, that the radius measured this way is not very accurate, owing to the uncertainty in the distance. • Is ...
... • We can measure the temperature of a star relatively easily by its spectral type or color. If the distance is known, then we can measure its luminosity, and then compute its radius. Note, however, that the radius measured this way is not very accurate, owing to the uncertainty in the distance. • Is ...
Lesson 3 - The Life Cycle of Stars - Hitchcock
... • Although black holes are invisible, they can be observed by the gravitational effect they have on their surroundings. • Matter swirls around a black hole just before being pulled in. The matter becomes so hot that it emits X-rays. • Astronomers use X-rays and other means to locate black holes, eve ...
... • Although black holes are invisible, they can be observed by the gravitational effect they have on their surroundings. • Matter swirls around a black hole just before being pulled in. The matter becomes so hot that it emits X-rays. • Astronomers use X-rays and other means to locate black holes, eve ...
What is the life cycle of a star?
... • Although black holes are invisible, they can be observed by the gravitational effect they have on their surroundings. • Matter swirls around a black hole just before being pulled in. The matter becomes so hot that it emits X-rays. • Astronomers use X-rays and other means to locate black holes, eve ...
... • Although black holes are invisible, they can be observed by the gravitational effect they have on their surroundings. • Matter swirls around a black hole just before being pulled in. The matter becomes so hot that it emits X-rays. • Astronomers use X-rays and other means to locate black holes, eve ...
PDF Full-text
... Figure 4 shows a comparison of the 1150–3140 Å solar spectrum with that of the M5 V star GJ 876 observed by the COS instrument on HST [41]. The fluxes for the two stars are compared at a distance corresponding to the habitable zone of the host star. For the Sun, the distance is 1 AU, and for the muc ...
... Figure 4 shows a comparison of the 1150–3140 Å solar spectrum with that of the M5 V star GJ 876 observed by the COS instrument on HST [41]. The fluxes for the two stars are compared at a distance corresponding to the habitable zone of the host star. For the Sun, the distance is 1 AU, and for the muc ...
Document
... stars in many of the evolutionary phases. Can test timescale, surface temperature and luminosity predictions. After 30 years of testing, it looks like we understand the basic evolution of stars very well. (2) My personal favorite test is the measurement of radioactive Tc in AGB stars. ...
... stars in many of the evolutionary phases. Can test timescale, surface temperature and luminosity predictions. After 30 years of testing, it looks like we understand the basic evolution of stars very well. (2) My personal favorite test is the measurement of radioactive Tc in AGB stars. ...
SPECTROSCOPY - AST 114, Astronomy Lab II for Spring 2017!
... strongest hydrogen spectral lines were labeled as spectral class A, then B, C, D, etc. all the way down to N. Why did some stars showed strong hydrogen features while others did not? The physical significance was unclear. In 1901 another scientist in the Harvard lab, Annie Jump Cannon, created her o ...
... strongest hydrogen spectral lines were labeled as spectral class A, then B, C, D, etc. all the way down to N. Why did some stars showed strong hydrogen features while others did not? The physical significance was unclear. In 1901 another scientist in the Harvard lab, Annie Jump Cannon, created her o ...
Stellar and emission line spectra
... A star, being a fuzzy ball of hot gas, does not have the same kind of well-defined surface as, for instance, a rocky planet. Instead, the density of a star drops more or less smoothly from the centre outwards, approaching the interstellar density far out from the star. The radius of a star is merely ...
... A star, being a fuzzy ball of hot gas, does not have the same kind of well-defined surface as, for instance, a rocky planet. Instead, the density of a star drops more or less smoothly from the centre outwards, approaching the interstellar density far out from the star. The radius of a star is merely ...
The First Stars in the Universe
... but most of the heavier elements are created only by the thermonuclear fusion reactions in stars, so they would not have been present before the first stars had formed. Astronomers use the term “metals” for all these heavier elements. The young metal-rich stars in the Milky Way are called Population ...
... but most of the heavier elements are created only by the thermonuclear fusion reactions in stars, so they would not have been present before the first stars had formed. Astronomers use the term “metals” for all these heavier elements. The young metal-rich stars in the Milky Way are called Population ...
Mass determinations of PMS stars with the
... Results and future prospectives • In an 8 years campaign of spectroscopical observations we have discovered 9 PMS SB with period > 50 days that are suitable for observations with AMBER • We already had observations of BS Indi (K=6.6 mag) with AMBER but the signal resulted to be too faint (+ no stan ...
... Results and future prospectives • In an 8 years campaign of spectroscopical observations we have discovered 9 PMS SB with period > 50 days that are suitable for observations with AMBER • We already had observations of BS Indi (K=6.6 mag) with AMBER but the signal resulted to be too faint (+ no stan ...
The star Epsilon UMa, or more commonly known as Alioth
... stars in a spectral type refer to the fact that the spectral types are each broken up into a decimal type system ranging from 0 to 9. Stars that are classified as A0 are earlier stars and are higher in temperature then the later A9 stars. Alioth is labeled as an A0 star which means that it is one of ...
... stars in a spectral type refer to the fact that the spectral types are each broken up into a decimal type system ranging from 0 to 9. Stars that are classified as A0 are earlier stars and are higher in temperature then the later A9 stars. Alioth is labeled as an A0 star which means that it is one of ...
My power point presentation on spectroscopy of stars (ppt file)
... • Sometime fitting works reasonably well, but not perfectly • In this case we can often obtain approximate values of parameters such as chemical abundances, rotation, … • The remaining discrepancies give us information about physics missing from the model • For the supergiant omicron Scorpii, the di ...
... • Sometime fitting works reasonably well, but not perfectly • In this case we can often obtain approximate values of parameters such as chemical abundances, rotation, … • The remaining discrepancies give us information about physics missing from the model • For the supergiant omicron Scorpii, the di ...
ASTRONOMY 113 Laboratory Lab 5: Spectral Classification of the
... Some of the most beautiful objects in the sky are star clusters, groups of stars ranging in number from a few hundreds of stars ("open clusters") to a few million stars ("globular star clusters"). All of the stars in these clusters are bound to each other by gravity. Star clusters are also valuable ...
... Some of the most beautiful objects in the sky are star clusters, groups of stars ranging in number from a few hundreds of stars ("open clusters") to a few million stars ("globular star clusters"). All of the stars in these clusters are bound to each other by gravity. Star clusters are also valuable ...
Abundances of RGB stars in NGC 6752 Grundahl
... that the bulk of the light-element inhomogeneities are the result of a process other than mixing, i.e., that the present abundance variations are of “primordial” origin. The primordial scenario, and variations on it, has been proposed and discussed several times before in the literature (see for exa ...
... that the bulk of the light-element inhomogeneities are the result of a process other than mixing, i.e., that the present abundance variations are of “primordial” origin. The primordial scenario, and variations on it, has been proposed and discussed several times before in the literature (see for exa ...
Stars PowerPoint
... – A star that begins with a mass between about 8 and 20 times the Sun’s mass will end up with a core that is too massive to be supported by electron pressure. – Once no further energy-producing reactions can occur, the core of the star violently collapses in on itself and protons and electrons in th ...
... – A star that begins with a mass between about 8 and 20 times the Sun’s mass will end up with a core that is too massive to be supported by electron pressure. – Once no further energy-producing reactions can occur, the core of the star violently collapses in on itself and protons and electrons in th ...
doc - Pocket Stars
... Survey if you have an internet connection. You can zoom in and out using the "+" and "-" buttons. Note that SDSS does not cover the entire sky: most objects in the range M80 to M100 are within the survey. ...
... Survey if you have an internet connection. You can zoom in and out using the "+" and "-" buttons. Note that SDSS does not cover the entire sky: most objects in the range M80 to M100 are within the survey. ...
Power Point Presentation
... where they burn hydrogen in nuclear reactions in their cores Burning rate is higher for more massive stars - hence their lifetimes on the main sequence are much shorter and they are rather rare Red dwarf stars are the most common as they burn hydrogen slowly and live the longest Often called dwarfs ...
... where they burn hydrogen in nuclear reactions in their cores Burning rate is higher for more massive stars - hence their lifetimes on the main sequence are much shorter and they are rather rare Red dwarf stars are the most common as they burn hydrogen slowly and live the longest Often called dwarfs ...
A prevalence of dynamo-generated magnetic fields in the
... during the main sequence, can persist through the red giant phase. This indicates that these dynamo-generated fields are frequently able to settle into long-lived stable configurations21,22. The occurrence rate of suppressed dipole modes in intermediate-mass red giants is much higher than the occurr ...
... during the main sequence, can persist through the red giant phase. This indicates that these dynamo-generated fields are frequently able to settle into long-lived stable configurations21,22. The occurrence rate of suppressed dipole modes in intermediate-mass red giants is much higher than the occurr ...
First Light Sources at the End of the Dark Ages: Direct
... was initiated within a few 100 Myr of the Big Bang and was completed by z~6. The sources of UV photons responsible for reionization, however, have yet to be identified observationally. Given the pristine nature of the intergalactic medium, consisting almost entirely of hydrogen and helium, the very ...
... was initiated within a few 100 Myr of the Big Bang and was completed by z~6. The sources of UV photons responsible for reionization, however, have yet to be identified observationally. Given the pristine nature of the intergalactic medium, consisting almost entirely of hydrogen and helium, the very ...
Evolution of Warm Debris Around Sun-like Stars: Clues to Terrestrial
... It appears that stars younger than 100-300 Myr are more likely to exhibit IR excess. Note that our results are dominated by field stars, whereas the work of Gorlova et al. (2006) and Siegler et al. (2006) focus on open clusters. The results are roughly consistent with models for a collisional casca ...
... It appears that stars younger than 100-300 Myr are more likely to exhibit IR excess. Note that our results are dominated by field stars, whereas the work of Gorlova et al. (2006) and Siegler et al. (2006) focus on open clusters. The results are roughly consistent with models for a collisional casca ...
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.