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... Great Lick Refractor (this old instrument is a huge 57 feet long!) Ellie does her research on adaptive optics using a sodium laser attached to the Shane 120”, to create an upper-atmosphere target, and a motorized array of mirrors that work to correct atmospheric fluctuations in the final image. The ...
... Great Lick Refractor (this old instrument is a huge 57 feet long!) Ellie does her research on adaptive optics using a sodium laser attached to the Shane 120”, to create an upper-atmosphere target, and a motorized array of mirrors that work to correct atmospheric fluctuations in the final image. The ...
l~ JHd 111
... periodie variations in the light-eurve and radial velocity. And it is more than 100 years aga that the first star of this elass was deteeted, with its eharaeteristies and speetaeular behaviour: a normally very faint star brightens for a few days, 2-5 rn above its normal magnitude. These outbursts oe ...
... periodie variations in the light-eurve and radial velocity. And it is more than 100 years aga that the first star of this elass was deteeted, with its eharaeteristies and speetaeular behaviour: a normally very faint star brightens for a few days, 2-5 rn above its normal magnitude. These outbursts oe ...
Molecular gas in z~6 quasar host galaxies
... • The CO detections suggest the presence of highly excited molecular gas in the quasar host galaxies, with molecular gas masses on order of 1010 Msun. The gas mass and line width distributions are similar to that of the CO detected SMGs and quasars at z from 1 to 5. • FIR-CO luminosity relation: Act ...
... • The CO detections suggest the presence of highly excited molecular gas in the quasar host galaxies, with molecular gas masses on order of 1010 Msun. The gas mass and line width distributions are similar to that of the CO detected SMGs and quasars at z from 1 to 5. • FIR-CO luminosity relation: Act ...
HS 0702+6043: a star showing both short-period p
... From the uncontaminated optical spectrum of HS 0702+6043, we can easily exclude a potential F- or G-type main sequence companion. Because the star is relatively faint, 2MASS photometry is only accurate enough to require that any hypothetical companion must be later than K-type. At the supposed 1 h o ...
... From the uncontaminated optical spectrum of HS 0702+6043, we can easily exclude a potential F- or G-type main sequence companion. Because the star is relatively faint, 2MASS photometry is only accurate enough to require that any hypothetical companion must be later than K-type. At the supposed 1 h o ...
Hill Sphere
... Jupiter and Saturn are composed primarily of hydrogen and helium, yet the heavy elements may hold the key to their formation. They have more heavy elements than were present in the protosolar gas. Were the heavy elements the first to accrete, or did the enrichment occur at later stages? Depending on ...
... Jupiter and Saturn are composed primarily of hydrogen and helium, yet the heavy elements may hold the key to their formation. They have more heavy elements than were present in the protosolar gas. Were the heavy elements the first to accrete, or did the enrichment occur at later stages? Depending on ...
Spectral line mapping of the Milky Way
... outflows. However, even more important will be the availability of a coherent picture of all phases of the interstellar medium, to study their interrelationship. This includes answering questions on how the atomic gas evolves into molecular gas, creating the molecular clouds from which new stars wil ...
... outflows. However, even more important will be the availability of a coherent picture of all phases of the interstellar medium, to study their interrelationship. This includes answering questions on how the atomic gas evolves into molecular gas, creating the molecular clouds from which new stars wil ...
Peak Bagging of red giant stars observed by Kepler: first results with
... Since the first detection of non-radial oscillations in cool giant stars [8], the asteroseismology of field red giants (RGs) has encountered a substantial increase, especially thanks to the advent of the spacebased photometric missions CoRoT (e.g. [20,19]) and Kepler (e.g. [16, 15]), where the latter ...
... Since the first detection of non-radial oscillations in cool giant stars [8], the asteroseismology of field red giants (RGs) has encountered a substantial increase, especially thanks to the advent of the spacebased photometric missions CoRoT (e.g. [20,19]) and Kepler (e.g. [16, 15]), where the latter ...
Current Challenges Facing Planet Transit Surveys
... method: Ground-based photometry was likely to succeed only for gas-giant planets, yet such planets were expected only at large distances. Even if all Sun-like stars had a Jupiter, transiting systems would be rare (only 1 in 1000 systems would have the inclination to transit), and, worse yet, the tra ...
... method: Ground-based photometry was likely to succeed only for gas-giant planets, yet such planets were expected only at large distances. Even if all Sun-like stars had a Jupiter, transiting systems would be rare (only 1 in 1000 systems would have the inclination to transit), and, worse yet, the tra ...
Astrophysical false positives in direct imaging for exoplanets: a white
... the Near Infrared (SINFONI, see Eisenhauer et al. 2003; Bonnet et al. 2004b,a) mounted at the VLT/UT4. SINFONI provides AO assisted integral field spectroscopy in the near-infrared. It is composed by the SPectrograph for Infrared Faint Field Imaging (SPIFFI) fed by a modified version of the Multi-Ap ...
... the Near Infrared (SINFONI, see Eisenhauer et al. 2003; Bonnet et al. 2004b,a) mounted at the VLT/UT4. SINFONI provides AO assisted integral field spectroscopy in the near-infrared. It is composed by the SPectrograph for Infrared Faint Field Imaging (SPIFFI) fed by a modified version of the Multi-Ap ...
LATE STAGES OF CLOSE BINARY SYSTEMS 1. Introduction The X
... 1976). This limit may, in real life, be somewhat higher still if one takes into account that helium stars more massive than about 4 A f o r 5Af are likely to be identified with WolfRayet stars, which are observed to undergo substantial mass loss by stellar wind. Mass loss rates between \QT*M^yx' and ...
... 1976). This limit may, in real life, be somewhat higher still if one takes into account that helium stars more massive than about 4 A f o r 5Af are likely to be identified with WolfRayet stars, which are observed to undergo substantial mass loss by stellar wind. Mass loss rates between \QT*M^yx' and ...
a new planet around an m dwarf: revealing a correlation between
... spanned by Doppler-based planet searches. For example, the solarmass FGK dwarfs that comprise the bulk of the California and Carnegie Planet Search (CCPS) span stellar masses from 0.8 to 1.2 M (Valenti & Fischer 2005; Takeda et al. 2007). Much more leverage can be gained by measuring the planet occ ...
... spanned by Doppler-based planet searches. For example, the solarmass FGK dwarfs that comprise the bulk of the California and Carnegie Planet Search (CCPS) span stellar masses from 0.8 to 1.2 M (Valenti & Fischer 2005; Takeda et al. 2007). Much more leverage can be gained by measuring the planet occ ...
Magnetic Fields in Stars
... compass—and magnetic fields have been found in some hundreds of stars during the past 50 yr. Magnetic fields have been detected in T Tauri stars and other pre-mainsequence stars, several types of main sequence stars, white dwarfs and neutron stars. We now know a number of methods by which such magne ...
... compass—and magnetic fields have been found in some hundreds of stars during the past 50 yr. Magnetic fields have been detected in T Tauri stars and other pre-mainsequence stars, several types of main sequence stars, white dwarfs and neutron stars. We now know a number of methods by which such magne ...
Gamma-ray burst has highest redshift yet seen
... wait patiently for observers. They shine for millions of years. But a GRB’s afterglow grows fainter with every passing hour. “So we’re obliged to move fast,” says Fox. How is one to promptly identify high-z GRBs and catch their IR afterglow fast enough to yield spectra adequate for studying cosmic r ...
... wait patiently for observers. They shine for millions of years. But a GRB’s afterglow grows fainter with every passing hour. “So we’re obliged to move fast,” says Fox. How is one to promptly identify high-z GRBs and catch their IR afterglow fast enough to yield spectra adequate for studying cosmic r ...
Lecture 2. Isolated Neutron Stars – I.
... Accretion in close binaries Accretion is the most powerful source of energy realized in Nature, which can give a huge energy output. When matter fall down onto the surface of a neutron star up to 10% of mc2 can be released. ...
... Accretion in close binaries Accretion is the most powerful source of energy realized in Nature, which can give a huge energy output. When matter fall down onto the surface of a neutron star up to 10% of mc2 can be released. ...
Two distinct sequences of blue straggler stars in the globular cluster
... Creek ACT 2611, Australia Stars in globular clusters are generally believed to have all formed at the same time, early in the Galaxy's history1. 'Blue stragglers' are stars sufficiently massive2 that they should have evolved into white dwarfs long ago. Two possible mechanisms have been proposed for ...
... Creek ACT 2611, Australia Stars in globular clusters are generally believed to have all formed at the same time, early in the Galaxy's history1. 'Blue stragglers' are stars sufficiently massive2 that they should have evolved into white dwarfs long ago. Two possible mechanisms have been proposed for ...
PH109 Exploring the Universe, Test#4, Spring 2005 Please indicate
... a) strong radio sources identified with star-like images on photographs b) variable sources of light c) bright galaxies, and only later found to be radio sources d) the only type of radio source within our galaxy 17. Which type of galaxy contains the least amount of interstellar material? a) Ellipti ...
... a) strong radio sources identified with star-like images on photographs b) variable sources of light c) bright galaxies, and only later found to be radio sources d) the only type of radio source within our galaxy 17. Which type of galaxy contains the least amount of interstellar material? a) Ellipti ...
L129 DISCOVERY OF A NEW 89 SECOND X
... Spectral analysis of relatively faint X-ray sources at low Galactic latitudes is complicated by the presence of diffuse emission from the Galactic ridge. Recent work by Valinia & Marshall (1998) indicates that the pointing direction of XTE J1906109 is outside the bright, thin component of the ridge ...
... Spectral analysis of relatively faint X-ray sources at low Galactic latitudes is complicated by the presence of diffuse emission from the Galactic ridge. Recent work by Valinia & Marshall (1998) indicates that the pointing direction of XTE J1906109 is outside the bright, thin component of the ridge ...
Weighing Ultracompact Dwarf Galaxies in the Fornax Cluster
... ties. Unlike globular clusters which are characterised by a more or less constant size (~ 3 pc half-light radius), the sizes of UCDs increase with luminosity reaching half-light radii of ~ 100 pc. Some of the brighter UCDs exhibit a small low- surface-brightness envelope with exten sions up to se ...
... ties. Unlike globular clusters which are characterised by a more or less constant size (~ 3 pc half-light radius), the sizes of UCDs increase with luminosity reaching half-light radii of ~ 100 pc. Some of the brighter UCDs exhibit a small low- surface-brightness envelope with exten sions up to se ...
Document
... Physical size =840(0.5/57.3)= 7xdiameter Earth. => Earth orbits Sun, Was ignored. Modern distance ≈ 12000 diameter Determined by parallax ...
... Physical size =840(0.5/57.3)= 7xdiameter Earth. => Earth orbits Sun, Was ignored. Modern distance ≈ 12000 diameter Determined by parallax ...
The Correlation of Lithium and Beryllium in F and G
... Although Li has been extensively observed in main-sequence field and cluster stars, there are relatively fewer observations of Be. We have obtained Keck HIRES spectra of 36 late F and early G dwarfs in order to study the Li-Be correlation we found previously in the temperature regime of 5900–6650 K. ...
... Although Li has been extensively observed in main-sequence field and cluster stars, there are relatively fewer observations of Be. We have obtained Keck HIRES spectra of 36 late F and early G dwarfs in order to study the Li-Be correlation we found previously in the temperature regime of 5900–6650 K. ...
Diapositive 1
... M (Aerts et al. 2006). Fig.3: HD163899, ~35 frequencies: p- & gmode, latter 1st time in a BSG. Great potential for asteroseismology (Saio et al. 2006). Fig.7: WR111 (top) cf. WR123 (bottom) & WR103 (middle). No P of A > 0.05 mmag (~40 x less cf. SMP models: Glatzel et al. 1993) for f = 10 – 1000 c/ ...
... M (Aerts et al. 2006). Fig.3: HD163899, ~35 frequencies: p- & gmode, latter 1st time in a BSG. Great potential for asteroseismology (Saio et al. 2006). Fig.7: WR111 (top) cf. WR123 (bottom) & WR103 (middle). No P of A > 0.05 mmag (~40 x less cf. SMP models: Glatzel et al. 1993) for f = 10 – 1000 c/ ...
Magnetars origin and progenitors with enhanced rotation'
... • Roche lobe overflow by a primary. • Roche lobe overflow by a primary with a common envelope. • Roche lobe overflow by a secondary without a common envelope. • Roche lobe overflow by a secondary with a common envelope. ...
... • Roche lobe overflow by a primary. • Roche lobe overflow by a primary with a common envelope. • Roche lobe overflow by a secondary without a common envelope. • Roche lobe overflow by a secondary with a common envelope. ...
Grinin
... The Inner Regions of Protoplanetary Disks Williams and Cieza 2011, Protoplanetary Disks and Their Evolution ...
... The Inner Regions of Protoplanetary Disks Williams and Cieza 2011, Protoplanetary Disks and Their Evolution ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.