Astronomy Astrophysics Circumstellar emission in Be/X-ray binaries of the Magellanic
... that profoundly alters the emerging spectrum. Spectra of Be stars show some essential characteristics. 1) The Balmer lines are affected by the emission that is produced by bound-bound transitions in the envelope, which fills in the photospheric lines or drives them into emission. 2) Free-free transi ...
... that profoundly alters the emerging spectrum. Spectra of Be stars show some essential characteristics. 1) The Balmer lines are affected by the emission that is produced by bound-bound transitions in the envelope, which fills in the photospheric lines or drives them into emission. 2) Free-free transi ...
KIC 10449976: discovery of an extreme helium
... objects using the Isaac Newton Telescope (INT) in La Palma. One of the targets, KIC 10449976 (α = 18h 47m 14.s 1, δ = +47◦ 41 46. 9: J2000, g = 14.49), was observed because it was clearly blue (g − E-mail: [email protected] ...
... objects using the Isaac Newton Telescope (INT) in La Palma. One of the targets, KIC 10449976 (α = 18h 47m 14.s 1, δ = +47◦ 41 46. 9: J2000, g = 14.49), was observed because it was clearly blue (g − E-mail: [email protected] ...
SRMP Stars Curriculum - American Museum of Natural History
... outliers: one is close by and hot, but not on the list of brightest stars; and another is quite far away and cool, but on the list of brightest stars. Elicit that these represent a very small star, and a very large star, respectively. The worksheets include the completed versions of each plot, which ...
... outliers: one is close by and hot, but not on the list of brightest stars; and another is quite far away and cool, but on the list of brightest stars. Elicit that these represent a very small star, and a very large star, respectively. The worksheets include the completed versions of each plot, which ...
Stars, Galaxies, and the Universe Section 1
... hydrogen atoms within its core have fused into helium atoms. Giant Stars • A star’s shell of gases grows cooler as it expands. As the gases in the outer shell become cooler, they begin to glow with a reddish color. These stars are known as giants. • giant a very large and bright star whose hot core ...
... hydrogen atoms within its core have fused into helium atoms. Giant Stars • A star’s shell of gases grows cooler as it expands. As the gases in the outer shell become cooler, they begin to glow with a reddish color. These stars are known as giants. • giant a very large and bright star whose hot core ...
The Helium Flash • When the temperature of a stellar core reaches T
... still coming from the shell, the luminosity of the star drops. • Along with the drop in luminosity, the star also evolves blueward off the red giant branch. As the central core expands (due to the energy input from helium burning), the density and temperature in the hydrogen burning shell decreases. ...
... still coming from the shell, the luminosity of the star drops. • Along with the drop in luminosity, the star also evolves blueward off the red giant branch. As the central core expands (due to the energy input from helium burning), the density and temperature in the hydrogen burning shell decreases. ...
Rocky planetesimals as the origin of metals in DZ stars
... obvious pattern is seen, although there may be a higher density of DZA stars near the Galactic disc and perhaps also towards more modest speeds, but the former may be an observational bias due to diminished spectroscopic sensitivity. In any case, one should expect a correlation between these quantit ...
... obvious pattern is seen, although there may be a higher density of DZA stars near the Galactic disc and perhaps also towards more modest speeds, but the former may be an observational bias due to diminished spectroscopic sensitivity. In any case, one should expect a correlation between these quantit ...
Deep SDSS optical spectroscopy of distant halo stars I. Atmospheric
... Fig. 1. Sample BOSS spectra (black) for two representative low-metallicity F-type stars, a dwarf and a giant. The spectra are divided into 20 equal-velocity bins and normalized by their mean value in each bin, as described in the text. The best-fitting parameters and models (red curves) are shown. T ...
... Fig. 1. Sample BOSS spectra (black) for two representative low-metallicity F-type stars, a dwarf and a giant. The spectra are divided into 20 equal-velocity bins and normalized by their mean value in each bin, as described in the text. The best-fitting parameters and models (red curves) are shown. T ...
Red supergiants around the obscured open cluster Stephenson 2
... Context. Several clusters of red supergiants have been discovered in a small region of the Milky Way close to the base of the ScutumCrux Arm and the tip of the Long Bar. Population synthesis models indicate that they must be very massive to harbour so many supergiants. Amongst these clusters, Stephe ...
... Context. Several clusters of red supergiants have been discovered in a small region of the Milky Way close to the base of the ScutumCrux Arm and the tip of the Long Bar. Population synthesis models indicate that they must be very massive to harbour so many supergiants. Amongst these clusters, Stephe ...
Science Grade 08 Unit 11 Exemplar Lesson 02: Classifying Stars
... 5. Ask students to open their notebooks to the Handout: Galaxies and Stars Questions (previously distributed and affixed). 6. Project the Teacher Resource: PowerPoint: Galaxies and Stars, and discuss slides 7–9 with students. Instruct students to watch for underlined words or phrases as they continu ...
... 5. Ask students to open their notebooks to the Handout: Galaxies and Stars Questions (previously distributed and affixed). 6. Project the Teacher Resource: PowerPoint: Galaxies and Stars, and discuss slides 7–9 with students. Instruct students to watch for underlined words or phrases as they continu ...
Stars - Emera Astronomy Center
... Optional: Load the digital images onto a computer to display on a video projector. Each group may refer to these images, as well as their drawings, to describe their flame. In stars, just as in Earth-bound fires, blue is hotter than yellow, and yellow is hotter than red. The Sun is much hotter than ...
... Optional: Load the digital images onto a computer to display on a video projector. Each group may refer to these images, as well as their drawings, to describe their flame. In stars, just as in Earth-bound fires, blue is hotter than yellow, and yellow is hotter than red. The Sun is much hotter than ...
Magnetic fields in O-, B- and A-type stars on the main sequence
... Magnetic fields have first been discovered in the Sun [1] and in the chemically peculiar A-type star 78 Virginis [2]. These two stars are representative of two major groups of magnetic stars, which are directly related to the dominant mechanism of heat transport in the outer layers of the stars. For t ...
... Magnetic fields have first been discovered in the Sun [1] and in the chemically peculiar A-type star 78 Virginis [2]. These two stars are representative of two major groups of magnetic stars, which are directly related to the dominant mechanism of heat transport in the outer layers of the stars. For t ...
10 Measuring The Stars
... These are the 80 closest stars to us; note the dashed lines of constant radius. ...
... These are the 80 closest stars to us; note the dashed lines of constant radius. ...
New brown dwarfs and giant planets
... 4% of the sample would be classed as dark halo by Oppenheimer et al => ~2 x 10^-4 white dwarfs / pc^3 • Most of the Oppenheimer et al. white dwarfs are remnants of the first stars which formed in the thick disk • White dwarfs from the stellar halo account for the rest • There is no requirement for a ...
... 4% of the sample would be classed as dark halo by Oppenheimer et al => ~2 x 10^-4 white dwarfs / pc^3 • Most of the Oppenheimer et al. white dwarfs are remnants of the first stars which formed in the thick disk • White dwarfs from the stellar halo account for the rest • There is no requirement for a ...
Hot Horizontal Branch Stars in the Galactic Bulge. I
... D’Cruz et al. 1996). It may also be accomplished with deep mixing, and thus accompanied by light-element enhancements (Sweigart 1997; Kraft et al. 1998). However, binary mass transfer may play a dominant role at the hot end of the BHB, since a large fraction of field sdB/O stars are found to be bina ...
... D’Cruz et al. 1996). It may also be accomplished with deep mixing, and thus accompanied by light-element enhancements (Sweigart 1997; Kraft et al. 1998). However, binary mass transfer may play a dominant role at the hot end of the BHB, since a large fraction of field sdB/O stars are found to be bina ...
Metal-poor Stars
... presented in the figure, in a spectrum of a similarly unevolved Population III object, no metal features would be detectable since it contains no elements other than H, He and Li at its surface. Large numbers of metal-poor Galactic stars found in objective-prism surveys in both hemispheres have prov ...
... presented in the figure, in a spectrum of a similarly unevolved Population III object, no metal features would be detectable since it contains no elements other than H, He and Li at its surface. Large numbers of metal-poor Galactic stars found in objective-prism surveys in both hemispheres have prov ...
Properties of Wolf-Rayet Stars - Paul Crowther, University of Sheffield
... intrinsically weak emission lines. For example, HD 93131 (WN6ha) has a He ii λ4686 emission equivalent width which is an order of magnitude smaller than that observed in other WN6 stars; the ‘ha’ nomenclature indicates that hydrogen is seen both in absorption and emission. From a standard spectrosco ...
... intrinsically weak emission lines. For example, HD 93131 (WN6ha) has a He ii λ4686 emission equivalent width which is an order of magnitude smaller than that observed in other WN6 stars; the ‘ha’ nomenclature indicates that hydrogen is seen both in absorption and emission. From a standard spectrosco ...
Lab 7
... declination (think of this as a space latitude). The declination runs from -90° (celestial south pole) to +90° (celestial north pole). Both of these coordinates are laminated to the metal pole bases. In addition, the stars have been colored according to their spectral classes; blue balls represent O ...
... declination (think of this as a space latitude). The declination runs from -90° (celestial south pole) to +90° (celestial north pole). Both of these coordinates are laminated to the metal pole bases. In addition, the stars have been colored according to their spectral classes; blue balls represent O ...
The Hipparcos Star Globe Booklet - Cosmos
... The globe draws on the Hipparcos map of the sky: a colour, all-sky map in Galactic coordinates synthesised from Hipparcos and Tycho data products. The full-size map shows around 2.5 million of the brightest stars in the sky, as well as the luminous cloudy profile of the Milky Way itself. On the Hipp ...
... The globe draws on the Hipparcos map of the sky: a colour, all-sky map in Galactic coordinates synthesised from Hipparcos and Tycho data products. The full-size map shows around 2.5 million of the brightest stars in the sky, as well as the luminous cloudy profile of the Milky Way itself. On the Hipp ...
White dwarf cooling sequences and cosmochronology
... In all cases, the core is surrounded by a thin layer of pure helium with a mass ranging from 10−2 to 10−4 M . This layer is, in turn, surrounded by an even thinner layer of hydrogen with a typical mass lying in the range of 10−4 to 10−15 M . This layer is missing in ∼25% of the cases. From the phe ...
... In all cases, the core is surrounded by a thin layer of pure helium with a mass ranging from 10−2 to 10−4 M . This layer is, in turn, surrounded by an even thinner layer of hydrogen with a typical mass lying in the range of 10−4 to 10−15 M . This layer is missing in ∼25% of the cases. From the phe ...
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 ...
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 ...
Unit 13―The “Fixed” Stars
... and so jump by whole factors of 100 on the energy or luminosity scale, but we need to know luminosity values for single values of magnitude. That means we are looking for a number which when multiplied by its self five times equals 100. That is called the “fifth-root of 100.” And the ancients stuck ...
... and so jump by whole factors of 100 on the energy or luminosity scale, but we need to know luminosity values for single values of magnitude. That means we are looking for a number which when multiplied by its self five times equals 100. That is called the “fifth-root of 100.” And the ancients stuck ...
1 solar and stellar abundances of the elements
... represents the primordial composition of the solar system. The compositions of other stars may differ. A considerable body of astronomical evidence indicates that the stars in the neighborhood of the sun differ in age. Highly luminous stars transmute hydrogen into helium to produce energy at such a ...
... represents the primordial composition of the solar system. The compositions of other stars may differ. A considerable body of astronomical evidence indicates that the stars in the neighborhood of the sun differ in age. Highly luminous stars transmute hydrogen into helium to produce energy at such a ...
What is the minimum size of a star that will go supernova? A. Half
... Which type of star no longer creates its own energy? A. White dwarf B. Blue giant C. Red giant Answer: A. White dwarf A white dwarf is the leftover cooling core of a star. It gives off light as it cools, but can’t produce its own ...
... Which type of star no longer creates its own energy? A. White dwarf B. Blue giant C. Red giant Answer: A. White dwarf A white dwarf is the leftover cooling core of a star. It gives off light as it cools, but can’t produce its own ...
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.