High ions towards white dwarfs: circumstellar line shifts and stellar
... and, therefore, were not able to assign a photospheric velocity for the star. As a result, they interpreted the OVI detection, which is only slightly redshifted, as interstellar. In general it is possible to obtain a measurement of the photospheric velocity from the narrow core of the Hα line. Howev ...
... and, therefore, were not able to assign a photospheric velocity for the star. As a result, they interpreted the OVI detection, which is only slightly redshifted, as interstellar. In general it is possible to obtain a measurement of the photospheric velocity from the narrow core of the Hα line. Howev ...
Evolution of low mass stars
... The HRD inspired an English astronomer, Sir Arthur Stanley Eddington (18821944), when Russell visited London and presented his diagram at a meeting of the Royal Astronomical Society in 1913 (Eisberg, 2002). At the time, Eddington was the chief assistant of the Royal Greenwich Observatory. In 1926 Ed ...
... The HRD inspired an English astronomer, Sir Arthur Stanley Eddington (18821944), when Russell visited London and presented his diagram at a meeting of the Royal Astronomical Society in 1913 (Eisberg, 2002). At the time, Eddington was the chief assistant of the Royal Greenwich Observatory. In 1926 Ed ...
Neutral material around the B[e] supergiant star LHA 115
... and internal kinematics of these disks (or disk-like outflows) are well known. However, rapid rotation, lifting the material from the equatorial surface region, seems to play a fundamental role. Aims. The B[e] supergiant LHA 115-S 65 (in short: S 65) in the Small Magellanic Cloud is one of the two m ...
... and internal kinematics of these disks (or disk-like outflows) are well known. However, rapid rotation, lifting the material from the equatorial surface region, seems to play a fundamental role. Aims. The B[e] supergiant LHA 115-S 65 (in short: S 65) in the Small Magellanic Cloud is one of the two m ...
Evolution in circumstellar envelopes of Be stars: From disks to rings?
... height slowly decreases. Fe ii and other metal emission lines may become undetectable and/or their peak separation starts to shrink again. This phase lasts much longer than either of the previous two. The rate of change of all parameters declines with time, and gradually a new phase of relative quie ...
... height slowly decreases. Fe ii and other metal emission lines may become undetectable and/or their peak separation starts to shrink again. This phase lasts much longer than either of the previous two. The rate of change of all parameters declines with time, and gradually a new phase of relative quie ...
Paper by Bessell, Castelli and Plez on Model atmospheres
... sect. 2. The colors in the present paper essentially supersede those of Wood & Bessell (1994). In the 1993 flux data there was evidence of some discontinuities in the computed colors of A-G stars. Castelli (1996) explained how to eliminate these discontinuities which were related to a modification o ...
... sect. 2. The colors in the present paper essentially supersede those of Wood & Bessell (1994). In the 1993 flux data there was evidence of some discontinuities in the computed colors of A-G stars. Castelli (1996) explained how to eliminate these discontinuities which were related to a modification o ...
the PDF program book
... Reserve a Meeting Room There are five meeting rooms in UKK (rooms K1 – K4, K6) that may be used for meetings or telecons. The rooms are located on level 3 and seat between 12 and 24 people. If you want to hold a small meeting, you can either speak to the LOC representative at the registration desk o ...
... Reserve a Meeting Room There are five meeting rooms in UKK (rooms K1 – K4, K6) that may be used for meetings or telecons. The rooms are located on level 3 and seat between 12 and 24 people. If you want to hold a small meeting, you can either speak to the LOC representative at the registration desk o ...
X-Ray Properties of Young Stars and Stellar Clusters
... Although the environments of star and planet formation are thermodynamically cold, substantial X-ray emission from 10–100 MK plasmas is present. In low-mass pre-main-sequence stars, X-rays are produced by violent magnetic reconnection flares. In high-mass O stars, they are produced by wind shocks on ...
... Although the environments of star and planet formation are thermodynamically cold, substantial X-ray emission from 10–100 MK plasmas is present. In low-mass pre-main-sequence stars, X-rays are produced by violent magnetic reconnection flares. In high-mass O stars, they are produced by wind shocks on ...
Stars & Galaxies - newmanlib.ibri.org
... that they differ in brightness. • As one looks at the stars more carefully, it becomes apparent that they are not all the same color. • Look at the constellation of Orion shown in the next panel. ...
... that they differ in brightness. • As one looks at the stars more carefully, it becomes apparent that they are not all the same color. • Look at the constellation of Orion shown in the next panel. ...
SPIRou Science Case
... of a giant planet around 51 Peg (Mayor & Queloz 1995, Nature 378, 355), about 1,000 extra-solar planets have now been detected, revolutionizing planetary science by placing our unique solar system into a much broader context. More specifically, these discoveries allow us to explore the surprising di ...
... of a giant planet around 51 Peg (Mayor & Queloz 1995, Nature 378, 355), about 1,000 extra-solar planets have now been detected, revolutionizing planetary science by placing our unique solar system into a much broader context. More specifically, these discoveries allow us to explore the surprising di ...
The Ages of Stars
... arrive at an understanding of a process. Some examples include: • The formation and evolution of proto-planetary disks appear to occur in the first ∼ 100 Myr of a star’s life, with debris disks forming later. At present we can just barely limit this time-scale with the methods available, but clearly ...
... arrive at an understanding of a process. Some examples include: • The formation and evolution of proto-planetary disks appear to occur in the first ∼ 100 Myr of a star’s life, with debris disks forming later. At present we can just barely limit this time-scale with the methods available, but clearly ...
Quiescent and flaring X-ray emission from the nearby M/T dwarf
... SCR 1845 is not particularly young. The spectrum of the primary component is well described by an M 8.5 dwarf with T eff ≈ 2600 K, M ≈ 0.09 M and approximately solar metallicity. Adopting their J band magnitude (J = 9.58 ± 0.02) and bolometric corrections from Reid et al. (2001), we derived a bolome ...
... SCR 1845 is not particularly young. The spectrum of the primary component is well described by an M 8.5 dwarf with T eff ≈ 2600 K, M ≈ 0.09 M and approximately solar metallicity. Adopting their J band magnitude (J = 9.58 ± 0.02) and bolometric corrections from Reid et al. (2001), we derived a bolome ...
Spitzer Spectroscopy of Circumstellar Disks in the 5 Myr Old Upper
... photometric for all 3 nights with seeing conditions varying from 0.6–0.9′′ . HIRES was used with the red cross-disperser and the C5 decker (1.148′′×7.0′′ ), which has a projected slit width of 4 pixels and a spectral resolution of ∼33,000 (8.8 km s−1 ). The cross-disperser and echelle angles were se ...
... photometric for all 3 nights with seeing conditions varying from 0.6–0.9′′ . HIRES was used with the red cross-disperser and the C5 decker (1.148′′×7.0′′ ), which has a projected slit width of 4 pixels and a spectral resolution of ∼33,000 (8.8 km s−1 ). The cross-disperser and echelle angles were se ...
Stars: Intro & Classification Astronomy 1 — Elementary Astronomy LA Mission College
... Developed by Annie Jump Cannon Characteristic absorption lines determine stellar class Note: in Astronomy “metal” means anything “heavier” than He ...
... Developed by Annie Jump Cannon Characteristic absorption lines determine stellar class Note: in Astronomy “metal” means anything “heavier” than He ...
Full Text - Departement Natuurkunde en Sterrenkunde
... Strömgren photometric system . . . . . . . . . . . . . . . . . . . . . 165 ...
... Strömgren photometric system . . . . . . . . . . . . . . . . . . . . . 165 ...
Evolution of stars
... medium are cold and of a very low density because a. the lines are blue shifted. b. the lines are red shifted. c. the lines are extremely broad. d. the lines are extremely narrow. e. the lines are much darker than the stellar lines. Stars are born in a. reflection nebulae. b. dense molecular clouds. ...
... medium are cold and of a very low density because a. the lines are blue shifted. b. the lines are red shifted. c. the lines are extremely broad. d. the lines are extremely narrow. e. the lines are much darker than the stellar lines. Stars are born in a. reflection nebulae. b. dense molecular clouds. ...
A Method of Correcting Near-Infrared Spectra for Telluric Absorption
... standard,” whose intrinsic spectrum is known, to derive a system throughput curve that can then be applied to a target object spectrum observed nearby in the sky and close in time. Since T(l) varies with air mass and on timescales of the order of several to tens of minutes (depending on the atmosphe ...
... standard,” whose intrinsic spectrum is known, to derive a system throughput curve that can then be applied to a target object spectrum observed nearby in the sky and close in time. Since T(l) varies with air mass and on timescales of the order of several to tens of minutes (depending on the atmosphe ...
Astronomy Astrophysics Gaia-ESO Survey: The analysis of high-resolution The
... included for calibration purposes. For the WG11 analysis, it included a total of 1708 spectra of 1447 FGK-type stars (multiple exposures of benchmark stars were analyzed separately, see Sect. 7.1). From these stars, 1412 were observed by Gaia-ESO, 35 of them were obtained from data archives, and 22 ...
... included for calibration purposes. For the WG11 analysis, it included a total of 1708 spectra of 1447 FGK-type stars (multiple exposures of benchmark stars were analyzed separately, see Sect. 7.1). From these stars, 1412 were observed by Gaia-ESO, 35 of them were obtained from data archives, and 22 ...
A Variability Study of the Typical Red Supergiant Antares A
... many of the features of this variability have been associated with large convective cells. Unfortunately, due to the long timescales of these variations they are not well studied, with the exception of the bright M-class supergiant Betelgeuse (α Orionis, M2 Iab). Betelgeuse has been well studied bot ...
... many of the features of this variability have been associated with large convective cells. Unfortunately, due to the long timescales of these variations they are not well studied, with the exception of the bright M-class supergiant Betelgeuse (α Orionis, M2 Iab). Betelgeuse has been well studied bot ...
Ages of young stars
... (l) Cargile and James (2010), (m) Naylor et al. (2009), (n) derived by E. Mamajek using data from Hauck and Mermilliod (1998) and isochrones from Bertelli et al. (2009), (o) Ventura et al. (1998). ally negligible) and, presented separately, the systematic absolute age uncertainty estimated by Burke ...
... (l) Cargile and James (2010), (m) Naylor et al. (2009), (n) derived by E. Mamajek using data from Hauck and Mermilliod (1998) and isochrones from Bertelli et al. (2009), (o) Ventura et al. (1998). ally negligible) and, presented separately, the systematic absolute age uncertainty estimated by Burke ...
Ages of Young Stars
... (l) Cargile and James (2010), (m) Naylor et al. (2009), (n) derived by E. Mamajek using data from Hauck and Mermilliod (1998) and isochrones from Bertelli et al. (2009), (o) Ventura et al. (1998). ally negligible) and, presented separately, the systematic absolute age uncertainty estimated by Burke ...
... (l) Cargile and James (2010), (m) Naylor et al. (2009), (n) derived by E. Mamajek using data from Hauck and Mermilliod (1998) and isochrones from Bertelli et al. (2009), (o) Ventura et al. (1998). ally negligible) and, presented separately, the systematic absolute age uncertainty estimated by Burke ...
Astronomy Astrophysics - Niels Bohr Institutet
... All A5-G0 stars brighter than mvis = 8.3, G0 stars in the interval 8.30 ≤ mvis ≤ 8.40, and all G5 or just G stars (no subtypes) brighter than mvis = 8.6 were selected. On the one hand, the A5 spectral-type limit is early enough to include even quite metal-poor F stars; on the other hand, most K0-typ ...
... All A5-G0 stars brighter than mvis = 8.3, G0 stars in the interval 8.30 ≤ mvis ≤ 8.40, and all G5 or just G stars (no subtypes) brighter than mvis = 8.6 were selected. On the one hand, the A5 spectral-type limit is early enough to include even quite metal-poor F stars; on the other hand, most K0-typ ...
The Processing and Classification for the Spectra of Six Comets
... classification of comets is relatively rare, one of the reasons is the complexity of the comet’s composition, at a short distance from the sun, there will be the structures such as the coma, comet tail, and so on. The spectroscopic characteristics may differ with different structures[2] . However, from ...
... classification of comets is relatively rare, one of the reasons is the complexity of the comet’s composition, at a short distance from the sun, there will be the structures such as the coma, comet tail, and so on. The spectroscopic characteristics may differ with different structures[2] . However, from ...
Astrometric accuracy during the past 2000 years
... detailed comparisons, but it is difficult in many cases, if at all possible, to find sufficient information about this matter, and it cannot easily be presented in one line of a table. Internal errors are sometimes placed in brackets. The standard errors in the tables are sufficient for the original ...
... detailed comparisons, but it is difficult in many cases, if at all possible, to find sufficient information about this matter, and it cannot easily be presented in one line of a table. Internal errors are sometimes placed in brackets. The standard errors in the tables are sufficient for the original ...
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.