A5039237411- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Calibration and Measurement Techniques
- Adaptive optics and wavefront sensing
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- History and Developments in Astronomy
- Ionosphere and magnetosphere dynamics
- Pulsars and Gravitational Waves Research
- CCD and CMOS Imaging Sensors
- Atmospheric Ozone and Climate
- Geomagnetism and Paleomagnetism Studies
- Advanced Measurement and Metrology Techniques
- Scientific Measurement and Uncertainty Evaluation
- High-pressure geophysics and materials
- Optical Systems and Laser Technology
- Nuclear Physics and Applications
- Particle Detector Development and Performance
Center for Astrophysics Harvard & Smithsonian
2014-2024
Smithsonian Astrophysical Observatory
2011-2024
Harvard University
2000-2014
Harvard University Press
1993-2011
CFA Institute
2009-2010
California Institute of Technology
2010
Arcetri Astrophysical Observatory
2010
Liverpool John Moores University
2010
Radboud University Nijmegen
2009
University of South Africa
2009
The CIAO (<i>Chandra</i> Interactive Analysis of Observations) software package was first released in 1999 following the launch <i>Chandra</i> X-ray Observatory and is used by astronomers across world to analyze data as well from other telescopes. From earliest design discussions, planned a general-purpose scientific analysis system optimized for astronomy, consists mainly command line tools (allowing easy pipelining scripting) with parameter-based interface layered on flexible manipulation...
We present a self-consistent empirical model for several plasma parameters of polar coronal hole near solar minimum, derived from observations with the Solar and Heliospheric Observatory Ultraviolet Coronagraph Spectrometer. The describes radial distribution density electrons, H0, O5 + outflow velocity unresolved most probable velocities H0 during period between 1996 November 1997 April. In this Letter, we compare H I Lyα O VI λλ1032, 1037 emission lines spatial models parameters, iterate...
The Chandra Source Catalog (CSC) is a general purpose virtual X-ray astrophysics facility that provides access to carefully selected set of generally useful quantities for individual sources, and designed satisfy the needs broad-based group scientists, including those who may be less familiar with astronomical data analysis in regime. first release CSC includes information about 94,676 distinct sources detected subset public ACIS imaging observations from roughly eight years mission. This...
We present a comprehensive and self-consistent empirical model for several plasma parameters in the extended solar corona above polar coronal hole. The is derived from observations with SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) during period between 1996 November 1997 April. compare of H I Lyα O VI λλ1032, 1037 emission lines detailed three-dimensional models iterate optimal consistency measured synthesized observable quantities. Empirical constraints are obtained radial...
The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with High-Energy Transmission Grating (HETG) readout by Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at resolution comparable to that best ground-based visible-light observations. HETG-ACIS-S reveal, for first time, an inner ring within torus, suggestion hollow-tube knots along (perhaps) inward extension jet. Although...
Polaris, the nearest and brightest classical Cepheid, is a single-lined spectroscopic binary with an orbital period of 30 yr. Using High Resolution Channel Advanced Camera for Surveys on board Hubble Space Telescope (HST) at wavelength ∼2255 Å, we have directly detected faint companion separation 017. A second HST observation 1.04 yr later confirms motion in retrograde direction. By combining our two measures orbit Kamper analysis Hipparcos FK5 proper motions by Wielen et al., find mass...
We present the Chandra Multiwavelength Project (ChaMP) X-ray point source catalog with ~6800 sources detected in 149 observations covering ~10 deg2. The full ChaMP sample is 7 times larger than initial published catalog. exposure time of fields our ranges from 0.9 to 124 ks, corresponding a deepest flux limit f0.5-8.0 = 9 × 10-16 ergs cm-2 s-1. data have been uniformly reduced and analyzed ChaMP-specific pipelines then carefully validated by visual inspection. includes photometric eight...
We present high quality (high signal-to-noise ratio and moderate spectral resolution) near-infrared (near-IR) spectroscopic observations of 23 well-known broad-emission line active galactic nuclei (AGN). Additionally, we obtained simultaneous (within two months) optical spectroscopy similar quality. The near-IR broad emission spectrum AGN is dominated by permitted transitions hydrogen, helium, oxygen, calcium, the rich singly-ionized iron. In this paper spectra, identifications measurements,...
Abstract We report on the X-ray spectral and spatial evolution of symbiotic star R Aqr. Through a multiepoch observational campaign performed with Chandra between 2017 2022, we study emission this binary system, composed an evolved red giant white dwarf (WD). This analysis is particularly timely as WD approached periastron in late 2018/early 2019; thus, mass transfer, jet emission, outburst phenomena are to be expected. detailed analysis, detect significant rise soft (0.5–2 keV) Aqr, likely...
We present observations of two coronal mass ejections (CMEs) observed by the LASCO and EIT instruments on board Solar Heliospheric Observatory. One was 1997 April 30 other February 23. The latter CME is accompanied a spectacular prominence eruption reaches velocities about 900 km s-1, while former has no apparent accompanying attains only 300 s-1. However, CMEs are similar in appearance, having bright circular rims that can be interpreted as marking apexes expanding magnetic flux ropes, both...
The TRACE Observatory is the first solar-observing satellite in National Aeronautics and Space Administration’s (NASA) Small Explorer series. Launched April 2, 1998, it providing views of solar transition region low corona with unprecedented spatial temporal resolution. now seen to be highly filamented, filled flows other dynamic processes. Structure down resolution limit instrument, while variability motions are observed at all locations atmosphere, on very short time scales. Flares shock...
The Chandra Multi-wavelength Project (ChaMP) is a wide-area (~14 deg^2) survey of serendipitous X-ray sources, aiming to establish fair statistical samples covering wide range characteristics (such as absorbed AGNs, high z clusters galaxies) at flux levels (fX ~ 10^-15 - 10^-14 erg sec-1 cm-2) intermediate between the Deep surveys and previous missions. We present first ChaMP catalog, which consists 991 near on-axis, bright sources obtained from initial sample 62 observations. data have been...
The Mira AB system belongs to a class of detached binaries in which compact object accretes mass from the wind cool giant or supergiant. This provides unique laboratory for detailed study characteristics accretion processes because it can be spatially resolved with Hubble Space Telescope (HST) and components studied individually at UV optical wavelengths.
We study the spectral energy distributions and evolution of a large sample optically selected quasars from Sloan Digital Sky Survey that were observed in 323 Chandra images analyzed by Multiwavelength Project. Our highest-confidence matched includes 1135 X-ray detected redshift range 0.2 < z 5.4, representing some 36 Msec effective exposure. provide catalogs QSO properties, describe our novel method calculating flux upper limits sky coverage. Spectroscopic redshifts are available for about...
From multi-epoch adaptive optics imaging and integral field unit spectroscopy we report the discovery of an expanding narrowly confined bipolar shell surrounding helium nova V445 Puppis (Nova 2000).An equatorial dust disc obscures rem nant, outflow is characterised by a large polar velocity 6720 ± 650 km s-1 knots moving at even larger velocities 8450 570 .We derive expansion parallax distance 8.2 0.5 kpc deduce pre-outburst luminosity underlying binary log L /L q = 4.34 0.36.The derived lum...
This paper is the third in a series which we present deep Chandra ACIS-S imaging spectroscopy of Seyfert 1 galaxy NGC 4151, devoted to study its complex circum-nuclear X-ray emission. Emission features soft spectrum bright extended emission (L[0.3-2keV]~10^40 erg/s) at r>130 pc (2") are consistent with brighter OVII, OVIII, and NeIX lines seen HETGS XMM-Newton RGS spectra below 2 keV. We construct line images these find good morphological correlations narrow region clouds mapped [OIII]5007A....
We use quasi-simultaneous near-infrared (near-IR) and optical spectroscopy from four observing runs to study the continuum around 1 μm in 23 well-known broad emission line active galactic nuclei (AGN). show that, after correcting spectra for host galaxy light, AGN this wavelength can be approximated by sum of mainly two components, a hot dust blackbody an accretion disc. The disc spectrum appears dominate flux at ∼ μm, which allows us derive relation estimating black hole masses based on...
We report the discovery of kpc-scale diffuse emission in both hard continuum (3-6 keV) and Fe K alpha line Compton Thick (CT) Seyfert galaxy ESO428-G014. This extended component contains at least ~24% observed 3-8 keV emission, follows direction optical (ionization cone) radio jet. The has ~0.5% intrinsic 2-10 luminosity within bi-cones. A uniform scattering medium density 1 cm-3 would produce this a 1kpc path length Alternatively, higher column molecular clouds disk ESO428-G014 may be...
We report the Chandra ACIS-S detection of a bright soft X-ray transient in Mira AB interacting symbiotic-like binary. have resolved system for first time X-rays. Using and Hubble Space Telescope images, we determine that unprecedented outburst is likely associated with cool asymptotic giant branch (AGB) star, A, prototype class variables. X-rays never before been detected from an AGB recent activity signals undergoing dramatic changes. The total luminosity several times higher than estimated...
Although dust is widely found in astrophysics, forming surprisingly difficult. The proper combination of low temperature (<2000 K) and high density mainly the winds late-type giant supergiant stars that, as a result, are most efficient sources known. Dust ejected from these into interstellar medium has multiple important effects, including obscuring background objects enhancing star formation. We show here that quasars also naturally copious producers dust, if gas clouds producing their...
About half of the binary systems are close enough to each other for mass be exchanged between them at some point in their evolution, yet accretion mechanism wind accreting binaries is not well understood. We study dynamical effects gravitational focusing by a companion on winds from late-type stars. In particular, we investigate transfer and formation disks around secondary detached consisting an asymptotic giant branch (AGB) mass-losing star companion. The presence outflows studied as...