Interactive 4 - Hertzsprung-Russell Diagram Explorer
... stage of the evolution the star is in (e.g. Stellar nursery, Main sequence star, White dwarf), and the bottom left corner indicates the age of the star. ● Read “What’s going on” for a brief explanation of the processes occurring at each stage of evolution. ● Click “Continue” and watch the animation ...
... stage of the evolution the star is in (e.g. Stellar nursery, Main sequence star, White dwarf), and the bottom left corner indicates the age of the star. ● Read “What’s going on” for a brief explanation of the processes occurring at each stage of evolution. ● Click “Continue” and watch the animation ...
Historic mass loss from the RS Ophiuchi system
... Stars with an initial mass between ∼ 1 and ∼ 40 M¯ become hydrogen/heliumshell-burning Asymptotic Giant Branch (AGB) stars or core-helium-burning red supergiants (RSG). These phases are characterised by cool, molecular atmospheres giving rise to M spectral types (S or C for some chemically peculiar ...
... Stars with an initial mass between ∼ 1 and ∼ 40 M¯ become hydrogen/heliumshell-burning Asymptotic Giant Branch (AGB) stars or core-helium-burning red supergiants (RSG). These phases are characterised by cool, molecular atmospheres giving rise to M spectral types (S or C for some chemically peculiar ...
Accuracy of spectroscopy-based radioactive dating of stars
... The determination of absolute ages for stars is of paramount importance in astrophysics since ages allow the timescales on which stellar populations and their chemical composition evolve to be established. The presence of long-lived unstable elements in stellar atmospheres offers a way to date stars ...
... The determination of absolute ages for stars is of paramount importance in astrophysics since ages allow the timescales on which stellar populations and their chemical composition evolve to be established. The presence of long-lived unstable elements in stellar atmospheres offers a way to date stars ...
Observational studies of stellar rotation
... in the well-sampled, high S/N low frequency Fourier domain. The highest v sin i measured so far with this technique, ∼600 kms−1 , was reported for an O-type star in the Large Magellanic Cloud (Dufton et al. 2011). For a few bright stars, the Fourier technique may even provide an estimate of surface ...
... in the well-sampled, high S/N low frequency Fourier domain. The highest v sin i measured so far with this technique, ∼600 kms−1 , was reported for an O-type star in the Large Magellanic Cloud (Dufton et al. 2011). For a few bright stars, the Fourier technique may even provide an estimate of surface ...
WORD - Astrophysics
... overcome crowding, and a 100m class telescope is required to study the brighter galaxies at their half-light radius - without it work is limited to the less representative outer regions where crowding is less of an issue. The more luminous elliptical ...
... overcome crowding, and a 100m class telescope is required to study the brighter galaxies at their half-light radius - without it work is limited to the less representative outer regions where crowding is less of an issue. The more luminous elliptical ...
Behavior of Li abundances in solar-analog stars
... It is of astrophysical importance to study the abundance of lithium on the surface of late-type (F–G–K) stars; i.e., it in principle provides us with valuable information regarding the past history and the physical mechanism of stellar envelope mixing, since Li nuclei are burned and destroyed when t ...
... It is of astrophysical importance to study the abundance of lithium on the surface of late-type (F–G–K) stars; i.e., it in principle provides us with valuable information regarding the past history and the physical mechanism of stellar envelope mixing, since Li nuclei are burned and destroyed when t ...
on the pms star hbc 498 and its associated nebulous stars1
... The spectral types of the visually brightest program stars are given in Table 3. They were determined by intercomparison of our spectra with those of stars with known MK spectral types taken during different observing runs with the same instrumental setup (the SPMO grid, e.g., A96), and/or by interp ...
... The spectral types of the visually brightest program stars are given in Table 3. They were determined by intercomparison of our spectra with those of stars with known MK spectral types taken during different observing runs with the same instrumental setup (the SPMO grid, e.g., A96), and/or by interp ...
1 - Piscataway High School
... of the gas would weigh more than an automobile. In this degenerate matter, the pressure does not depend on temperature, and that means the pressure–temperature thermostat does not regulate energy production. When the temperature becomes hot enough, helium fusion begins to make energy, and the temper ...
... of the gas would weigh more than an automobile. In this degenerate matter, the pressure does not depend on temperature, and that means the pressure–temperature thermostat does not regulate energy production. When the temperature becomes hot enough, helium fusion begins to make energy, and the temper ...
A History of Star Catalogues - The Albuquerque Astronomical Society
... catalogue was a means to this end. Using Tycho’s measurements, Kepler was able to formulate his three laws. (Kusukawa 1999) ...
... catalogue was a means to this end. Using Tycho’s measurements, Kepler was able to formulate his three laws. (Kusukawa 1999) ...
Chapter 15 Stars, Galaxies, and Universe
... •Hydrogen fuses to become helium and releases a lot of energy •When star uses up hydrogen helium can start fusing and creating new elements •Helium fuses in core to become carbon, oxygen •Massive stars produce heavier elements like iron •Stars without fuel become white dwarf, neutron star or black h ...
... •Hydrogen fuses to become helium and releases a lot of energy •When star uses up hydrogen helium can start fusing and creating new elements •Helium fuses in core to become carbon, oxygen •Massive stars produce heavier elements like iron •Stars without fuel become white dwarf, neutron star or black h ...
The low-mass dispersed population around the Lupus clouds
... given temperature. The Lupus clouds that we targeted are placed at 150 − 200 pc from us (Comerón 2008) and the members of their confirmed populations have ages of a few Myr or less. This makes our observations of the Lupus clouds very well suited for the identification of candidate members on the s ...
... given temperature. The Lupus clouds that we targeted are placed at 150 − 200 pc from us (Comerón 2008) and the members of their confirmed populations have ages of a few Myr or less. This makes our observations of the Lupus clouds very well suited for the identification of candidate members on the s ...
The Young Stars
... are called FU Orionis eruptive variables, or FU Ori objects. The luminosities can reach a few hundred L . The two best studied members of the class, FU Ori and V1057 Cyg, have both exhibited increases in optical brightness by 5–6 mag on timescales of about a year, followed by gradual fading. The fr ...
... are called FU Orionis eruptive variables, or FU Ori objects. The luminosities can reach a few hundred L . The two best studied members of the class, FU Ori and V1057 Cyg, have both exhibited increases in optical brightness by 5–6 mag on timescales of about a year, followed by gradual fading. The fr ...
The Deaths of Very Massive Stars
... SN Ibc. The remnant would probably be a neutron star. It is unclear if such events have been observed, though Cas A might be a candidate. Even if the core of the star collapses to a black hole, its death is not necessarily nucleosynthetically barren or unobservable. The black hole could result from ...
... SN Ibc. The remnant would probably be a neutron star. It is unclear if such events have been observed, though Cas A might be a candidate. Even if the core of the star collapses to a black hole, its death is not necessarily nucleosynthetically barren or unobservable. The black hole could result from ...
offprint
... years. The two main reasons for this interest are the very strong, but rare outbursts, one of which started recently in 2001 (Štefl et al. 2001, 2003b, hereafter Paper I), and the well known short periodicity, analyzed by Štefl et al. (2003a, hereafter Paper II). The periodic line profile variabil ...
... years. The two main reasons for this interest are the very strong, but rare outbursts, one of which started recently in 2001 (Štefl et al. 2001, 2003b, hereafter Paper I), and the well known short periodicity, analyzed by Štefl et al. (2003a, hereafter Paper II). The periodic line profile variabil ...
DUSTY CIRCUMSTELLAR DISKS B. Zuckerman
... Association (hereafter TWA) is about 10 million years old and only ∼60 pc from Earth (Webb et al. 1999). The primary reason this close T Tauri Association went unrecognized for so long is that the massive molecular cloud from which the Association stars formed has dissipated; the only clouds that re ...
... Association (hereafter TWA) is about 10 million years old and only ∼60 pc from Earth (Webb et al. 1999). The primary reason this close T Tauri Association went unrecognized for so long is that the massive molecular cloud from which the Association stars formed has dissipated; the only clouds that re ...
Hot subdwarf stars-galactic orbits and distribution perpendicular to
... Hot subdwarfs are blue, horizontal-branch like stars, representing the late stages of evolution of stars having started with less than about 2.5 M⊙ on the main sequence. The hotter subdwarf B (sdB) stars form a well defined group. Their luminosity is of the order of 10 L⊙ and their surface temperatu ...
... Hot subdwarfs are blue, horizontal-branch like stars, representing the late stages of evolution of stars having started with less than about 2.5 M⊙ on the main sequence. The hotter subdwarf B (sdB) stars form a well defined group. Their luminosity is of the order of 10 L⊙ and their surface temperatu ...
Spectroscopic Atlas for Amateur Astronomers
... beginners, very difficult to make the link to the highly blended lines of their own, in most cases lowly resolved profiles. Here at last it becomes clear, why spectral atlases need to be created for specific degrees of resolution. Recently the pocket guide “A Spectroscopic Atlas of Bright Stars” [9] ...
... beginners, very difficult to make the link to the highly blended lines of their own, in most cases lowly resolved profiles. Here at last it becomes clear, why spectral atlases need to be created for specific degrees of resolution. Recently the pocket guide “A Spectroscopic Atlas of Bright Stars” [9] ...
A spectroscopic investigation of the O-type star - ORBi
... evidence of binarity is found can never be definitely considered as single. Even if no RV shift is detected, the system could be seen under a particular orientation, have a very long period or perhaps a high eccentricity, thereby making the RV variations not significant over a long timescale. We per ...
... evidence of binarity is found can never be definitely considered as single. Even if no RV shift is detected, the system could be seen under a particular orientation, have a very long period or perhaps a high eccentricity, thereby making the RV variations not significant over a long timescale. We per ...
Astronomy Astrophysics Detailed abundances of a large sample of giant stars in... and in the Sagittarius nucleus
... comprehensive reviews): their stars do not satisfy the very definition of a simple stellar population (SSP). In contrast, all the evidence suggests that GCs had a significant and very peculiar chemical evolution including self-enrichment of metals from ejecta of massive stars early in their lifetime ...
... comprehensive reviews): their stars do not satisfy the very definition of a simple stellar population (SSP). In contrast, all the evidence suggests that GCs had a significant and very peculiar chemical evolution including self-enrichment of metals from ejecta of massive stars early in their lifetime ...
Article PDF - IOPscience
... communication) places the star inside the 20 pc region, and the DC star LHS 1247 (0123−262) since its distance, estimated from the photometric observations of Bergeron et al. (1997, hereafter BRL97), places this candidate inside our region of interest, within the uncertainties. We also include two D ...
... communication) places the star inside the 20 pc region, and the DC star LHS 1247 (0123−262) since its distance, estimated from the photometric observations of Bergeron et al. (1997, hereafter BRL97), places this candidate inside our region of interest, within the uncertainties. We also include two D ...
arXiv:astro-ph/0508448v1 22 Aug 2005
... stars. One system is known in which there is strong evidence for an origin through the dynamical ejection scenario. AE Aur and µ Col are both O9.5V stars with similar ages which are running away in opposite directions with velocities relative to the local standard of rest of 113.3 and 107.8 kms−1 re ...
... stars. One system is known in which there is strong evidence for an origin through the dynamical ejection scenario. AE Aur and µ Col are both O9.5V stars with similar ages which are running away in opposite directions with velocities relative to the local standard of rest of 113.3 and 107.8 kms−1 re ...
PowerPoint Presentation - Isolated Neutron Stars, solid crust
... observational resources have been devoted to study the faint thermal emission from neutron stars and to search for features in their spectrum. Isolated neutron stars play a key role in compact objects astrophysics: these are the only sources in which we can see directly the surface of the compact st ...
... observational resources have been devoted to study the faint thermal emission from neutron stars and to search for features in their spectrum. Isolated neutron stars play a key role in compact objects astrophysics: these are the only sources in which we can see directly the surface of the compact st ...
Excitation of Solar-like Oscillations: From PMS to MS Stellar Models
... oscillation life-times for α Cen A. Those data enable us to constrain P for that star. The approach adopted in the case of the sun has thus been extended to the case of α Cen A and large discrepancies have been found for this star between predicted P and “observed” P (see Samadi et al. 2004). For ot ...
... oscillation life-times for α Cen A. Those data enable us to constrain P for that star. The approach adopted in the case of the sun has thus been extended to the case of α Cen A and large discrepancies have been found for this star between predicted P and “observed” P (see Samadi et al. 2004). For ot ...
The self-enrichment of galactic halo globular clusters: a clue to their
... by Brown et al. within the context of the Fall and Rees theory. Following Jehin et al., thick disk and field halo stars were born in globular clusters from which they escaped either during an early disruption of the proto-globular cluster (Pop IIa) or through a later disruption or evaporation proces ...
... by Brown et al. within the context of the Fall and Rees theory. Following Jehin et al., thick disk and field halo stars were born in globular clusters from which they escaped either during an early disruption of the proto-globular cluster (Pop IIa) or through a later disruption or evaporation proces ...
Optical Spectroscopy of a Flare on Barnard`s Star
... to mass motions in the chromosphere- the Neupert effect (evaporation) or condensation. The Neupert effect is seen in ∼80% of large solar flares (McTiernan et al. 1999) as well as in some stellar flares (Hawley et al. 1995; Guedel et al. 1996). Unfortunately, by integrating over 30 minutes, sharp vel ...
... to mass motions in the chromosphere- the Neupert effect (evaporation) or condensation. The Neupert effect is seen in ∼80% of large solar flares (McTiernan et al. 1999) as well as in some stellar flares (Hawley et al. 1995; Guedel et al. 1996). Unfortunately, by integrating over 30 minutes, sharp vel ...
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.