Exploring the Universe
... • All stars are made up of hot, glowing gases • Stars can appear red, blue or yellow based on surface temperature – Hottest stars are blue, coolest are red – Hertzspurg-Russel diagram classifies stars • 90° of stars are called the main sequence • Other stars include red giants, supergiants, and dwar ...
... • All stars are made up of hot, glowing gases • Stars can appear red, blue or yellow based on surface temperature – Hottest stars are blue, coolest are red – Hertzspurg-Russel diagram classifies stars • 90° of stars are called the main sequence • Other stars include red giants, supergiants, and dwar ...
SEEING STARS! SEEING STARS!
... develop the modern agricultural tractor. His name lives on in the name of the Massey Ferguson company. ...
... develop the modern agricultural tractor. His name lives on in the name of the Massey Ferguson company. ...
P7 Further Physics : Observing the Universe
... eclipses of the Sun and Moon, apparent motion of planets and stars. Difference between solar and sidereal day. ...
... eclipses of the Sun and Moon, apparent motion of planets and stars. Difference between solar and sidereal day. ...
Recent science results from VLTI commissioning
... (from North to East). The points distribution reveals an extremely oblate shape with an aspect ratio 2a/2b = 1.56±0.05. ...
... (from North to East). The points distribution reveals an extremely oblate shape with an aspect ratio 2a/2b = 1.56±0.05. ...
Cepheid
... In Shapley’s day, the LMC and SMC were considered as two isolated offshoots of the Milky Way, different from the spiral nebulae. We now realize that they are ‘dwarf’ galaxies in their own right (but not spirals). ...
... In Shapley’s day, the LMC and SMC were considered as two isolated offshoots of the Milky Way, different from the spiral nebulae. We now realize that they are ‘dwarf’ galaxies in their own right (but not spirals). ...
Chemical analysis of 24 dusty (pre-) main
... in abundance analyses and the fairly high projected rotational velocities severely limit the amount of suitable lines. For a few slowly rotating stars (e.g. HD 18256, HD 20010, HD 104327 and HD 139614) we were able to use hundreds of lines in the analysis; the average value for the amount of lines i ...
... in abundance analyses and the fairly high projected rotational velocities severely limit the amount of suitable lines. For a few slowly rotating stars (e.g. HD 18256, HD 20010, HD 104327 and HD 139614) we were able to use hundreds of lines in the analysis; the average value for the amount of lines i ...
here - NASA/IPAC Extragalactic Database
... line, we call the O star an “Of-type”, with the implication that the star is of luminosity class “I”. (The actual system is a bit more complicated than this; see, e.g., Sota et al. 2011.) The NIII emission behavior has finally been demonstrated to be dependent on stellar wind strengths, although nit ...
... line, we call the O star an “Of-type”, with the implication that the star is of luminosity class “I”. (The actual system is a bit more complicated than this; see, e.g., Sota et al. 2011.) The NIII emission behavior has finally been demonstrated to be dependent on stellar wind strengths, although nit ...
Chapter 13 – Behavior of Spectral Lines
... The high excitation of the Balmer series (10.2 eV) means excitation continues to increase to high temperature (max at ~ 9000K). Most metal lines have disappeared by this temperature. Why? ...
... The high excitation of the Balmer series (10.2 eV) means excitation continues to increase to high temperature (max at ~ 9000K). Most metal lines have disappeared by this temperature. Why? ...
Bayesian mass and age estimates for transiting exoplanet host stars⋆
... where P and a are the period and semi-major axis of the Keplerian orbit and q = Mc /M is the mass ratio for a companion with mass Mc . The quantity (a/R ) can be determined with good precision from a high quality light curve alone if the orbit is known to be circular since it depends only on the d ...
... where P and a are the period and semi-major axis of the Keplerian orbit and q = Mc /M is the mass ratio for a companion with mass Mc . The quantity (a/R ) can be determined with good precision from a high quality light curve alone if the orbit is known to be circular since it depends only on the d ...
The empirical mass distribution of hot B subdwarfs
... asteroseismic analyses, including mass estimates, of 15 pulsating hot B subdwarfs have been published since a decade. The masses have also been reliably determined by light curve modeling and spectroscopy for 7 sdB components of eclipsing and/or reflection effect binaries. These empirical mass distr ...
... asteroseismic analyses, including mass estimates, of 15 pulsating hot B subdwarfs have been published since a decade. The masses have also been reliably determined by light curve modeling and spectroscopy for 7 sdB components of eclipsing and/or reflection effect binaries. These empirical mass distr ...
The Be/X-ray transient V0332153: evidence for a tilt between the
... We present optical and infrared observations of BQ Cam, the optical counterpart to the Be/ X-ray transient system V0332153. BQ Cam is shown to be an O8±9Ve star, which places V0332153 at a distance of ,7 kpc. Ha spectroscopy and infrared photometry are used to discuss the evolution of the circumstel ...
... We present optical and infrared observations of BQ Cam, the optical counterpart to the Be/ X-ray transient system V0332153. BQ Cam is shown to be an O8±9Ve star, which places V0332153 at a distance of ,7 kpc. Ha spectroscopy and infrared photometry are used to discuss the evolution of the circumstel ...
Life Histories Of Some Stars
... surface temperature, the bluer it appears. The cooler the surface, the redder it appears. Astronomers can also describe surface temperature (or color temperature) as a star’s spectral class. O stars are hottest and bluest. B stars are less blue, more white, and cooler. M stars are the reddest and co ...
... surface temperature, the bluer it appears. The cooler the surface, the redder it appears. Astronomers can also describe surface temperature (or color temperature) as a star’s spectral class. O stars are hottest and bluest. B stars are less blue, more white, and cooler. M stars are the reddest and co ...
Comparing stars - The Open University
... The H-R diagram can be represented in a number of different ways; the colour index of a star is a measure of its temperature and the spectral classification scheme is also a temperature sequence. Another way of representing stellar luminosity is through the absolute visual magnitude. It should be cl ...
... The H-R diagram can be represented in a number of different ways; the colour index of a star is a measure of its temperature and the spectral classification scheme is also a temperature sequence. Another way of representing stellar luminosity is through the absolute visual magnitude. It should be cl ...
Wolf-Rayet Stars
... W-R stars are divided into three broad spectroscopic classes (WN, WC and WO) based on the emission lines present in their spectrum. WN stars show emission lines predominantly of helium and nitrogen, although emission due to carbon, silicon, and hydrogen can readily be seen in some of these objects. ...
... W-R stars are divided into three broad spectroscopic classes (WN, WC and WO) based on the emission lines present in their spectrum. WN stars show emission lines predominantly of helium and nitrogen, although emission due to carbon, silicon, and hydrogen can readily be seen in some of these objects. ...
Do We Know of Any Maunder Minimum Stars?
... are: HD 9562 by Baliunas et al. (1995a), HD 167215 and HD 101177 by Donahue (1998), HD 45067, HD 89744, and HD 178428 by Saar (1998). According to the analysis here (§3.1) five of these stars, HD 9562, HD 167215, HD 45067, HD 89744, and HD 178428 have ∆MV values of 1.5, 0.5, 1.4, 1.1, and 0.8 respec ...
... are: HD 9562 by Baliunas et al. (1995a), HD 167215 and HD 101177 by Donahue (1998), HD 45067, HD 89744, and HD 178428 by Saar (1998). According to the analysis here (§3.1) five of these stars, HD 9562, HD 167215, HD 45067, HD 89744, and HD 178428 have ∆MV values of 1.5, 0.5, 1.4, 1.1, and 0.8 respec ...
Document
... skins inside the star. However, since fusion of iron uses up energy instead of releasing energy, fusion cannot ignite from Fe -- an iron core cannot support the weight of the outer layers. The collapse of this core — which occurs in a fraction of a second — results in a supernova that nearly obliter ...
... skins inside the star. However, since fusion of iron uses up energy instead of releasing energy, fusion cannot ignite from Fe -- an iron core cannot support the weight of the outer layers. The collapse of this core — which occurs in a fraction of a second — results in a supernova that nearly obliter ...
The first carbon-enhanced metal-poor star found in the Sculptor
... The origin of carbon-enhanced metal-poor (CEMP) stars and their possible connection with the chemical elements produced by the first stellar generation is still highly debated. In contrast to the Galactic halo, not many CEMP stars have been found in the dwarf spheroidal galaxies around the Milky Way ...
... The origin of carbon-enhanced metal-poor (CEMP) stars and their possible connection with the chemical elements produced by the first stellar generation is still highly debated. In contrast to the Galactic halo, not many CEMP stars have been found in the dwarf spheroidal galaxies around the Milky Way ...
classifying stars
... (HOW BRIGHT A STAR APPEARS.) However, if astronomers could take two stars and place them exactly the same distance from earth, they could tell which one really is brighter... unfortunately, this is not possible, but astronomers can measure the amount of light a star actually gives off. This is calle ...
... (HOW BRIGHT A STAR APPEARS.) However, if astronomers could take two stars and place them exactly the same distance from earth, they could tell which one really is brighter... unfortunately, this is not possible, but astronomers can measure the amount of light a star actually gives off. This is calle ...
16_Testbank
... 1) Briefly describe how a star forms. Answer: In cold, dense molecular clouds, gravity brings material together. As gas moves inwards it converts gravitational potential energy to thermal energy and warms up. Once the cloud becomes so dense that the thermal radiation cannot escape, the temperature r ...
... 1) Briefly describe how a star forms. Answer: In cold, dense molecular clouds, gravity brings material together. As gas moves inwards it converts gravitational potential energy to thermal energy and warms up. Once the cloud becomes so dense that the thermal radiation cannot escape, the temperature r ...
Word Document - Montana State University Extended
... hydrogen by nuclear fusion to produce helium in its core, and radiating energy mostly in the form of visible light. The measure of a star’s radiation energy is called luminosity. Although it has been brighter in the past, the Sun has been shining this way for about 5 billion years, making it about h ...
... hydrogen by nuclear fusion to produce helium in its core, and radiating energy mostly in the form of visible light. The measure of a star’s radiation energy is called luminosity. Although it has been brighter in the past, the Sun has been shining this way for about 5 billion years, making it about h ...
The Birth and Evolution of Brown Dwarfs
... • In 1997, there were 319 objects in 231 systems known within 10 parsecs of the Sun. • In ~ 4 years, 8 new objects have been added, 5 isolated and 3 companions to stars. SpT: M9-T8. • The brightest star in the sample is Sirius (Mv=1.4), the faintest is Gl570D (Mv~31). ...
... • In 1997, there were 319 objects in 231 systems known within 10 parsecs of the Sun. • In ~ 4 years, 8 new objects have been added, 5 isolated and 3 companions to stars. SpT: M9-T8. • The brightest star in the sample is Sirius (Mv=1.4), the faintest is Gl570D (Mv~31). ...
The Classification of Stellar Spectra
... Background: The History And Nature Of Spectral Classification Patterns of absorption lines were first observed in the spectrum of the sun by the German physicist Joseph von Fraunhofer early in the 1800’s, but it was not until late in the century that astronomers were able to routinely examine the sp ...
... Background: The History And Nature Of Spectral Classification Patterns of absorption lines were first observed in the spectrum of the sun by the German physicist Joseph von Fraunhofer early in the 1800’s, but it was not until late in the century that astronomers were able to routinely examine the sp ...
white dwarfs and the age of the universe
... the interstellar medium [9], winds and so on. There is now a broad opinion that the distinction among the character DA and non–DA is inherited (i.e., it is linked to the origin of the white dwarf itself) although a fraction of them can change their external aspect during the evolution [10]. Standard ...
... the interstellar medium [9], winds and so on. There is now a broad opinion that the distinction among the character DA and non–DA is inherited (i.e., it is linked to the origin of the white dwarf itself) although a fraction of them can change their external aspect during the evolution [10]. Standard ...
Astrophysics Lab “A”
... In this section we will qualitatively describe the physical mechanism which initiates and accelerates the winds of hot stars. The corresponding formalism will be introduced in Sect. 5. The essential effects are displayed in Fig. 2. • The deeper layers of the stellar atmosphere, the so-called photosp ...
... In this section we will qualitatively describe the physical mechanism which initiates and accelerates the winds of hot stars. The corresponding formalism will be introduced in Sect. 5. The essential effects are displayed in Fig. 2. • The deeper layers of the stellar atmosphere, the so-called photosp ...
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.