Counting Sunspots - Lunar and Planetary Institute
... the face of the Sun is not always the same, but goes up and down in a cycle. Historical records of Games sunspot counts show that this sunspot cycle has an average period of about eleven years. The 11 year sunspot cycle is related to a 22 year cycle for the reversal of the Sun's magnetic field. http ...
... the face of the Sun is not always the same, but goes up and down in a cycle. Historical records of Games sunspot counts show that this sunspot cycle has an average period of about eleven years. The 11 year sunspot cycle is related to a 22 year cycle for the reversal of the Sun's magnetic field. http ...
Particle Physics from Stars
... hEgrav i, leads to contraction and to an increase of hEkin i. Therefore, all else being equal, axion losses lead to contraction and heating. The nuclear energy generation rate scales with a high power of the temperature. Therefore, the heating implied by the new energy loss causes increased nuclear ...
... hEgrav i, leads to contraction and to an increase of hEkin i. Therefore, all else being equal, axion losses lead to contraction and heating. The nuclear energy generation rate scales with a high power of the temperature. Therefore, the heating implied by the new energy loss causes increased nuclear ...
X-Ray Spectroscopy of Stars
... Stars are among the most prominent sources accessible to modern X-ray telescopes. In fact, stars located across almost all regions of a Hertzsprung-Russell diagram have been identified as X-ray sources, with only a few exceptions, most notably A-type stars and the coolest giants of spectral type M. ...
... Stars are among the most prominent sources accessible to modern X-ray telescopes. In fact, stars located across almost all regions of a Hertzsprung-Russell diagram have been identified as X-ray sources, with only a few exceptions, most notably A-type stars and the coolest giants of spectral type M. ...
X-ray astronomy of stellar coronae (Review)
... of internal dynamos will only be touched upon in so far as stellar observations are contributing specifically to our knowledge. I also note that insights relating to our subject provide diagnostics that reach out to entirely different fields, such as studies of the rotational history of stars, the i ...
... of internal dynamos will only be touched upon in so far as stellar observations are contributing specifically to our knowledge. I also note that insights relating to our subject provide diagnostics that reach out to entirely different fields, such as studies of the rotational history of stars, the i ...
Stellar Oscillations Lecture Notes on Jørgen Christensen-Dalsgaard
... in two modes, in most cases identified as the fundamental and the first overtone of radial pulsation. While measurement of a single mode, as discussed above, provides a measure of the mean density of the star, two periods roughly speaking allow determination of its mass and radius. It is striking th ...
... in two modes, in most cases identified as the fundamental and the first overtone of radial pulsation. While measurement of a single mode, as discussed above, provides a measure of the mean density of the star, two periods roughly speaking allow determination of its mass and radius. It is striking th ...
Here - NASA/IPAC Extragalactic Database
... Planetary nebulae (PNe) are evolutionary products of so-called intermediate mass stars (initial masses of 1 – 8 M ) as they progress from the asymptotic giant branch (AGB) to the white dwarf stage. It is the interaction of the slow AGB wind with the fast post-AGB wind which produces the nebula. Bec ...
... Planetary nebulae (PNe) are evolutionary products of so-called intermediate mass stars (initial masses of 1 – 8 M ) as they progress from the asymptotic giant branch (AGB) to the white dwarf stage. It is the interaction of the slow AGB wind with the fast post-AGB wind which produces the nebula. Bec ...
T3-Cosmic Star Formation History
... pace. Multiwavelength imaging surveys with the Hubble (HST) and Spitzer space telescopes and ground-based facilities, together with spectroscopic follow-up with 8-m-class telescopes, have led to the discovery of galaxies with confirmed redshifts as large as z = 7.5 (Finkelstein et al. 2013) as well a ...
... pace. Multiwavelength imaging surveys with the Hubble (HST) and Spitzer space telescopes and ground-based facilities, together with spectroscopic follow-up with 8-m-class telescopes, have led to the discovery of galaxies with confirmed redshifts as large as z = 7.5 (Finkelstein et al. 2013) as well a ...
Mercury Flyby 3 - Messenger - The Johns Hopkins University
... • Prior to January of this year, Mercury had been visited by only one spacecraft; NASA’s Mariner 10 examined less than half the surface (~45%) in detail during its three flybys in 1974 and 1975. ...
... • Prior to January of this year, Mercury had been visited by only one spacecraft; NASA’s Mariner 10 examined less than half the surface (~45%) in detail during its three flybys in 1974 and 1975. ...
Short-period comets
... • The orbits of the short-period comets are ellipses of moderate eccentricity and inclination (Figure 3). Most of comets have inclinations of less than 30 relative to the ecliptic plane. Their eccentricities lie mostly 0.2-0.7. The perihelion distances of most comets are1-2AU. • Several comets have ...
... • The orbits of the short-period comets are ellipses of moderate eccentricity and inclination (Figure 3). Most of comets have inclinations of less than 30 relative to the ecliptic plane. Their eccentricities lie mostly 0.2-0.7. The perihelion distances of most comets are1-2AU. • Several comets have ...
arXiv:astro-ph/0703091v1 5 Mar 2007
... Pd and 129 I in meteorites is due to the injection into the solar nebula of s-process material from outside the edge of the helium-exhausted core of a massive star. If this interpretation is valid, then one observational basis for two r-process sites may not be solid. Inconsistencies between abundan ...
... Pd and 129 I in meteorites is due to the injection into the solar nebula of s-process material from outside the edge of the helium-exhausted core of a massive star. If this interpretation is valid, then one observational basis for two r-process sites may not be solid. Inconsistencies between abundan ...
SOHO`s Frequently Asked Questions
... distance, by the way.) The Sun is powered by nuclear reactions that happen in its core. In a nuclear reaction, matter is changed directly to energy. The pressure at the Suns center is so high that hydrogen atoms fuse together to become helium atoms + energy. This is related to Einstein's famous equa ...
... distance, by the way.) The Sun is powered by nuclear reactions that happen in its core. In a nuclear reaction, matter is changed directly to energy. The pressure at the Suns center is so high that hydrogen atoms fuse together to become helium atoms + energy. This is related to Einstein's famous equa ...
Science with the Constellation
... 1.1 Decade of Discovery A major goal of science is to understand how our Universe arrived at its present state and to understand its ultimate destiny. Over the past decade, astronomy has been revolutionized by observing with large ground-based telescopes, such as the 10 m Keck Observatory, and by ob ...
... 1.1 Decade of Discovery A major goal of science is to understand how our Universe arrived at its present state and to understand its ultimate destiny. Over the past decade, astronomy has been revolutionized by observing with large ground-based telescopes, such as the 10 m Keck Observatory, and by ob ...
PSRD: Chondrules: Important, but Possibly Unfathomable
... largest are only a couple of centimeters across)? Do the sizes reflect their formation conditions or subsequent sorting? http://www.psrd.hawaii.edu/April17/chondrules.html ...
... largest are only a couple of centimeters across)? Do the sizes reflect their formation conditions or subsequent sorting? http://www.psrd.hawaii.edu/April17/chondrules.html ...
9 The Clearing of Protoplanetary Disks and of the Protosolar Nebula
... observed in L-band, out to about 1 AU from T Tauri stars. Fig. 9.2 shows the fraction of T Tauri stars (mostly K and M stars) with IR excess at IRAC wavelengths (3.6, 4.5, 5.8, and 8µm, full circles). In addition to the data (and references) presented in Hernández et al. (2008) we have included the ...
... observed in L-band, out to about 1 AU from T Tauri stars. Fig. 9.2 shows the fraction of T Tauri stars (mostly K and M stars) with IR excess at IRAC wavelengths (3.6, 4.5, 5.8, and 8µm, full circles). In addition to the data (and references) presented in Hernández et al. (2008) we have included the ...
The distributions and ages of refractory objects in the solar nebula
... 0.1–1 cm sized objects, such as the large CAIs, would have drift inwards at rates of 1–10 cm/s. Thus CAIs would drift inward from 2 AU (the inner edge of the asteroid belt) to the inner edge of the disk in as little as 105 years. Two primary models have been invoked to explain how CAIs were not on ...
... 0.1–1 cm sized objects, such as the large CAIs, would have drift inwards at rates of 1–10 cm/s. Thus CAIs would drift inward from 2 AU (the inner edge of the asteroid belt) to the inner edge of the disk in as little as 105 years. Two primary models have been invoked to explain how CAIs were not on ...
Search for solar axions with the CAST experiment
... Periodical measurements show that CAST points to the Sun within the required precision ...
... Periodical measurements show that CAST points to the Sun within the required precision ...
MERCURY In-flight calibration of the PHEBUS UV instrument and
... A unique feature of Mercury’s space environment is its strongly coupled surfaceexosphere-magnetosphere-solar wind system, which can be remotely monitored by space missions such as Mariner 10, MESSENGER and soon BepiColombo and by ground-based observatories. Mercury’s exosphere is a very complex medi ...
... A unique feature of Mercury’s space environment is its strongly coupled surfaceexosphere-magnetosphere-solar wind system, which can be remotely monitored by space missions such as Mariner 10, MESSENGER and soon BepiColombo and by ground-based observatories. Mercury’s exosphere is a very complex medi ...
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... Testing the validity of the theoretical model of stochastic excitation with the help of 3D simulations of the outer layers of stellar models is the main goal of the present paper. For that purpose, we compare the p-mode excitation rates for stars with different temperatures and luminosities as obtai ...
... Testing the validity of the theoretical model of stochastic excitation with the help of 3D simulations of the outer layers of stellar models is the main goal of the present paper. For that purpose, we compare the p-mode excitation rates for stars with different temperatures and luminosities as obtai ...
Advanced Composition Explorer
Advanced Composition Explorer (ACE) is a NASA Explorers program Solar and space exploration mission to study matter comprising energetic particles from the solar wind, the interplanetary medium, and other sources. Real-time data from ACE is used by the NOAA Space Weather Prediction Center to improve forecasts and warnings of solar storms. The ACE robotic spacecraft was launched August 25, 1997 and entered a Lissajous orbit close to the L1 Lagrangian point (which lies between the Sun and the Earth at a distance of some 1.5 million km from the latter) on December 12, 1997. The spacecraft is currently operating at that orbit. Because ACE is in a non-Keplerian orbit, and has regular station-keeping maneuvers, the orbital parameters at right are only approximate. The spacecraft is still in generally good condition in 2015, and is projected to have enough fuel to maintain its orbit until 2024. NASA Goddard Space Flight Center managed the development and integration of the ACE spacecraft.