00 T Tauri Stars Have Extensive Coronae?
... If there is substantial disagreement between an observational result and its expectation from established theory, astronomers tend to speak of a "problem". One of those problems wh ich bothered optical and UV astronomers during the past years is the discrepancy of the observed ratio of the Lya and H ...
... If there is substantial disagreement between an observational result and its expectation from established theory, astronomers tend to speak of a "problem". One of those problems wh ich bothered optical and UV astronomers during the past years is the discrepancy of the observed ratio of the Lya and H ...
PHYSICAL PROPERTIES OF THE AXP 4U 0142+61 FROM X
... (2006a) through a different and spectral model-independent analysis. Because it shows this large disagreement, we also tried a fit where the column density is fixed at the latter value. The resulting fit is unacceptable, with 2 ¼ 3:83 for 1533 dof, kT ¼ 0:40 0:01 keV, and photon index ¼ 2:83 0 ...
... (2006a) through a different and spectral model-independent analysis. Because it shows this large disagreement, we also tried a fit where the column density is fixed at the latter value. The resulting fit is unacceptable, with 2 ¼ 3:83 for 1533 dof, kT ¼ 0:40 0:01 keV, and photon index ¼ 2:83 0 ...
Acta Polytechnica
... (kT ∼ 20 keV) gas, and its contribution is not negligible in the interpretation of the hard X-ray origin, it is essential to determine the thermal component with high accuracy. This motivated us to carry out the joint Suzaku+XMM-Newton/Chandra spectral analysis under the multi-T model. As a result, ...
... (kT ∼ 20 keV) gas, and its contribution is not negligible in the interpretation of the hard X-ray origin, it is essential to determine the thermal component with high accuracy. This motivated us to carry out the joint Suzaku+XMM-Newton/Chandra spectral analysis under the multi-T model. As a result, ...
TDE in the XMM-Newton slew survey
... 7 events found in slew survey, 3 are well monitored Mix of soft and soft+hard – don’t know how many just hard Index=5/3 over long-term curve but highly variable in detail. Unsure if variability intrinsic or ionised absorption or both. At least one found in E+A galaxy Hard emission most likely from C ...
... 7 events found in slew survey, 3 are well monitored Mix of soft and soft+hard – don’t know how many just hard Index=5/3 over long-term curve but highly variable in detail. Unsure if variability intrinsic or ionised absorption or both. At least one found in E+A galaxy Hard emission most likely from C ...
PPT - Chandra X-Ray Observatory
... Four processes can disturb equilibrium between gravitation and levitation; potentially responsible for metal-poor hot DAs: • Mass-loss tends to homogenize chemical stratification. However, M-dot drops below critical limit (10-16 M/yr) for Teff<70,000 K (Unglaub & Bues 1998). So, LB1919 should not b ...
... Four processes can disturb equilibrium between gravitation and levitation; potentially responsible for metal-poor hot DAs: • Mass-loss tends to homogenize chemical stratification. However, M-dot drops below critical limit (10-16 M/yr) for Teff<70,000 K (Unglaub & Bues 1998). So, LB1919 should not b ...
High Energy Phenomena in Supergiant X-ray Binaries - HAL-Insu
... General characteristics SFXTs constitute a new class of ∼ 12 sources identified among the recently discovered IGRs. They are HMXBs hosting NS orbiting around sgOB companion stars, exhibiting peculiar characteristics compared to “classical” HMXBs: rapid outbursts lasting only for hours, faint quiesce ...
... General characteristics SFXTs constitute a new class of ∼ 12 sources identified among the recently discovered IGRs. They are HMXBs hosting NS orbiting around sgOB companion stars, exhibiting peculiar characteristics compared to “classical” HMXBs: rapid outbursts lasting only for hours, faint quiesce ...
A Compact Central Object in the Supernova Remnant Kes 79
... The blackbody spectrum strongly suggests that the central point source in Kes 79 is not a foreground star or background AGN, as are the other unresolved sources in Figure 1. The central location and similarity to other recently-discovered objects (see list 2 below) indicate that this is probably a n ...
... The blackbody spectrum strongly suggests that the central point source in Kes 79 is not a foreground star or background AGN, as are the other unresolved sources in Figure 1. The central location and similarity to other recently-discovered objects (see list 2 below) indicate that this is probably a n ...
An X-ray and Radio Study of the Varying Expansion Velocities in
... and southwestern sides of the remnant are about a factor of two higher than those in the east and northeast. We showed in an earlier work that this is related to an offset of the explosion site from the geometric center of the remnant due to a density gradient in the ISM, and using our refined measu ...
... and southwestern sides of the remnant are about a factor of two higher than those in the east and northeast. We showed in an earlier work that this is related to an offset of the explosion site from the geometric center of the remnant due to a density gradient in the ISM, and using our refined measu ...
What happens close to a black hole?
... 3. SXT : Soft X-ray Telescope using conical-foil mirrors A eff ≈ 200 cm2 ; FOV = 0.50; (~3‘ res); 0.3-8 keV; E/ΔE ≈ 20 to 50. 4. SSM : Scanning Sky Monitor (SSM) with 3 PSPCs and ...
... 3. SXT : Soft X-ray Telescope using conical-foil mirrors A eff ≈ 200 cm2 ; FOV = 0.50; (~3‘ res); 0.3-8 keV; E/ΔE ≈ 20 to 50. 4. SSM : Scanning Sky Monitor (SSM) with 3 PSPCs and ...
Active X-ray Optics - High Energy Astrophysics Division
... How can we observe these objects? Ultraviolet emission is absorbed by the intervening intergalactic medium (IGM), and redshifting means that the universe is opaque to all UV and optical wavelengths out at z=10. The millimeter band is excellent to probe up to high redshifts, and ALMA will do this. Ho ...
... How can we observe these objects? Ultraviolet emission is absorbed by the intervening intergalactic medium (IGM), and redshifting means that the universe is opaque to all UV and optical wavelengths out at z=10. The millimeter band is excellent to probe up to high redshifts, and ALMA will do this. Ho ...
New INTEGRAL High Mass X
... Owocki et al. 1997, Lamers & Cassinelli 1999: line-driven winds from supergiant stars are highly variable ...
... Owocki et al. 1997, Lamers & Cassinelli 1999: line-driven winds from supergiant stars are highly variable ...
Full 11x8.5" Calendar, High Resolution - Chandra X
... This deep image from NASA’s Chandra X-ray Observatory shows the Vela pulsar, a neutron star that was formed when a massive star collapsed. In the upper right is a fast moving jet of particles produced by the pulsar. The pulsar is about 1,000 light years from Earth, and makes over 11 complete rotatio ...
... This deep image from NASA’s Chandra X-ray Observatory shows the Vela pulsar, a neutron star that was formed when a massive star collapsed. In the upper right is a fast moving jet of particles produced by the pulsar. The pulsar is about 1,000 light years from Earth, and makes over 11 complete rotatio ...
Lecture 1, Overview and Basic Concepts (April 2)
... - Hubble Space Telescope (ACS or WFC3 imaging) Proposals will be peer-reviewed by the class near the end of the quarter. Grading will be based on both the proposal and participation in the review. No Final Exam, but the last homework will be due during finals week. ...
... - Hubble Space Telescope (ACS or WFC3 imaging) Proposals will be peer-reviewed by the class near the end of the quarter. Grading will be based on both the proposal and participation in the review. No Final Exam, but the last homework will be due during finals week. ...
Semiar PPT
... 3. The rapid fall off of the early x-ray afterglow suggests that -ray emission is produced by a short lived source; we find that it is most likely SSC at a distance of ~ 1016 cm baryonic jets have a few problems. 4. X-ray lightcurves show flares on time scale of minutes to a day suggesting that t ...
... 3. The rapid fall off of the early x-ray afterglow suggests that -ray emission is produced by a short lived source; we find that it is most likely SSC at a distance of ~ 1016 cm baryonic jets have a few problems. 4. X-ray lightcurves show flares on time scale of minutes to a day suggesting that t ...
Black Hole Binaries in Quiescence
... • XRB: assume that supply of mass is constant, and that variability is due to accretion flow instabilities • AGN: assume significant changes in mass supply (tidal disruption etc) ...
... • XRB: assume that supply of mass is constant, and that variability is due to accretion flow instabilities • AGN: assume significant changes in mass supply (tidal disruption etc) ...
X-ray Polarimetry - XMM-Newton Science Operations Centre
... temperature, location) have not been well constrained by spectra or temporal signatures • Polarization provides a means to do this… ...
... temperature, location) have not been well constrained by spectra or temporal signatures • Polarization provides a means to do this… ...
X-ray binaries
... The latest large catalogue (Li et al. arXiv: 0707.0544) includes 187 galactic and Magellanic Clouds LMXBs with NSs and BHs as accreting components. Donors can be WDs, or normal low-mass stars (main sequence or sub-giants). Many sources are found in globular clusters. Also there are more and more LMX ...
... The latest large catalogue (Li et al. arXiv: 0707.0544) includes 187 galactic and Magellanic Clouds LMXBs with NSs and BHs as accreting components. Donors can be WDs, or normal low-mass stars (main sequence or sub-giants). Many sources are found in globular clusters. Also there are more and more LMX ...
ISOLATED, MASSIVE SUPERGIANTS NEAR THE GALACTIC
... The probability that this increase in flux resulted from a constant flux was <2 ; 107 under a 2 test. We find no evidence that the hardness of the spectrum varied during the outburst. We defined a hardness ratio (h s)/(h þ s), using s as the number of counts in the 0.5–3.0 keV band and h as the ...
... The probability that this increase in flux resulted from a constant flux was <2 ; 107 under a 2 test. We find no evidence that the hardness of the spectrum varied during the outburst. We defined a hardness ratio (h s)/(h þ s), using s as the number of counts in the 0.5–3.0 keV band and h as the ...
Black Holes in Binary Systems and Galaxy Nuclei
... Search for binary supermassive BHs in galactic nuclei (e.g. Sanders and Mirabel, 1996; Komossa et al., 2003). Observations of X-ray and ultraviolet-optical flares from the tidal disruption of stars near supermassive BHs in galactic nuclei (Komossa et al., 1997, 2002; Gezari et al., 2012). Investigat ...
... Search for binary supermassive BHs in galactic nuclei (e.g. Sanders and Mirabel, 1996; Komossa et al., 2003). Observations of X-ray and ultraviolet-optical flares from the tidal disruption of stars near supermassive BHs in galactic nuclei (Komossa et al., 1997, 2002; Gezari et al., 2012). Investigat ...
intro - Big Bear Solar Observatory
... For the longitudinal component of the photospheric magnetic field the energy dissipation, per unit mass in a unit of time, can be written (Monin & Yaglom 1975): ...
... For the longitudinal component of the photospheric magnetic field the energy dissipation, per unit mass in a unit of time, can be written (Monin & Yaglom 1975): ...
Name - MIT
... A) corona, core, convection zone, radiation zone, photosphere, chromosphere B) core, radiation zone, convection zone, photosphere, chromosphere, corona C) photosphere, chromosphere, core, radiation zone, convection zone, corona D) core, radiation zone, corona, convection zone, chromosphere, photosph ...
... A) corona, core, convection zone, radiation zone, photosphere, chromosphere B) core, radiation zone, convection zone, photosphere, chromosphere, corona C) photosphere, chromosphere, core, radiation zone, convection zone, corona D) core, radiation zone, corona, convection zone, chromosphere, photosph ...
Document
... Chandra finds gas at 1kev with density ~ 30 cc in an area of size 10 arcsec surrounding the BH (Baganoff et al. 2001); the capture radius for this gas is ~ 1 arcsec. ...
... Chandra finds gas at 1kev with density ~ 30 cc in an area of size 10 arcsec surrounding the BH (Baganoff et al. 2001); the capture radius for this gas is ~ 1 arcsec. ...
X-ray binaries
... The latest large catalogue (Li et al. arXiv: 0707.0544) includes 187 galactic and Magellanic Clouds LMXBs with NSs and BHs as accreting components. Donors can be WDs, or normal low-mass stars (main sequence or sub-giants). Many sources are found in globular clusters. Also there are more and more LMX ...
... The latest large catalogue (Li et al. arXiv: 0707.0544) includes 187 galactic and Magellanic Clouds LMXBs with NSs and BHs as accreting components. Donors can be WDs, or normal low-mass stars (main sequence or sub-giants). Many sources are found in globular clusters. Also there are more and more LMX ...
Quiescent and flaring X-ray emission from the nearby M/T dwarf
... Aims. X-ray emission is an important diagnostics to study magnetic activity in very low mass stars that are presumably fully convective and have an effectively neutral photosphere. Methods. We investigate an XMM-Newton observation of SCR 1845-6357, a nearby, ultracool M 8.5 / T 5.5 dwarf binary. The ...
... Aims. X-ray emission is an important diagnostics to study magnetic activity in very low mass stars that are presumably fully convective and have an effectively neutral photosphere. Methods. We investigate an XMM-Newton observation of SCR 1845-6357, a nearby, ultracool M 8.5 / T 5.5 dwarf binary. The ...
Most-likely Black Holes
... If BH formation through Case B (in giant stage) is possible, contrary to the observation, we should see about 10 times more BHs in our Galaxy. ...
... If BH formation through Case B (in giant stage) is possible, contrary to the observation, we should see about 10 times more BHs in our Galaxy. ...
X-ray astronomy
X-ray astronomy is an observational branch of astronomy which deals with the study of X-ray observation and detection from astronomical objects. X-radiation is absorbed by the Earth's atmosphere, so instruments to detect X-rays must be taken to high altitude by balloons, sounding rockets, and satellites. X-ray astronomy is the space science related to a type of space telescope that can see farther than standard light-absorption telescopes, such as the Mauna Kea Observatories, via x-ray radiation.X-ray emission is expected from astronomical objects that contain extremely hot gasses at temperatures from about a million kelvin (K) to hundreds of millions of kelvin (MK). Although X-rays have been observed emanating from the Sun since the 1940s, the discovery in 1962 of the first cosmic X-ray source was a surprise. This source is called Scorpius X-1 (Sco X-1), the first X-ray source found in the constellation Scorpius. The X-ray emission of Scorpius X-1 is 10,000 times greater than its visual emission, whereas that of the Sun is about a million times less. In addition, the energy output in X-rays is 100,000 times greater than the total emission of the Sun in all wavelengths. Based on discoveries in this new field of X-ray astronomy, starting with Scorpius X-1, Riccardo Giacconi received the Nobel Prize in Physics in 2002. It is now known that such X-ray sources as Sco X-1 are compact stars, such as neutron stars or black holes. Material falling into a black hole may emit X-rays, but the black hole itself does not. The energy source for the X-ray emission is gravity. Infalling gas and dust is heated by the strong gravitational fields of these and other celestial objects.Many thousands of X-ray sources are known. In addition, the space between galaxies in galaxy clusters is filled with a very hot, but very dilute gas at a temperature between 10 and 100 megakelvins (MK). The total amount of hot gas is five to ten times the total mass in the visible galaxies.