A5023348633- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- History and Developments in Astronomy
- Galaxies: Formation, Evolution, Phenomena
- History of Science and Medicine
- Solar and Space Plasma Dynamics
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- CCD and CMOS Imaging Sensors
- Molecular Spectroscopy and Structure
- Atomic and Molecular Physics
- Spacecraft Design and Technology
- Particle Detector Development and Performance
- Calibration and Measurement Techniques
- Radio Astronomy Observations and Technology
- Optical Systems and Laser Technology
- Marine and coastal ecosystems
- Meteorological Phenomena and Simulations
- Space Exploration and Technology
- Adaptive optics and wavefront sensing
Smithsonian Astrophysical Observatory
2016-2024
Center for Astrophysics Harvard & Smithsonian
2019-2024
X-ray Instrumentation Associates (United States)
2021
American Society for Radiation Oncology
2021
Vanderbilt University
2013-2015
Rochester Institute of Technology
2008-2014
University of Rochester
2005
Bowling Green State University
2002
Cerro Tololo Inter-American Observatory
2002
Research Experiences for Undergraduates
2002
We present an overview of the initial results from Chandra Planetary Nebula Survey (ChanPlaNS), first systematic (volume-limited) X-ray Observatory survey planetary nebulae (PNe) in solar neighborhood. The phase ChanPlaNS targeted 21 mostly high-excitation PNe within ~1.5 kpc Earth, yielding 4 detections diffuse emission and 9 X-ray-luminous point sources at central stars (CSPNe) these objects. Combining with those obtained archival data for all (14) other that have been observed to date, we...
We have mapped the 12CO(3–2) line emission around Mira AB system at 0.̋5 resolution using Atacama Large Millimeter/submillimeter Array (ALMA). The CO map shows amazing complexity. circumstellar gas has been shaped by different dynamical actors during evolution of system, and several morphological components can be identified. companion is marginally resolved in continuum currently 0.̋487 ± 0.̋006 separation. In main component, centered on stellar velocity, spiral arcs A are found. appears to...
We present X-ray spectral analysis of 20 point-like sources detected in Chandra Planetary Nebula Survey observations 59 planetary nebulae (PNe) the solar neighborhood. Most these detections are associated with luminous central stars within relatively young, compact nebulae. The vast majority X-ray-emitting at PN cores display "hard" (⩾0.5 keV) emission components that unlikely to be due photospheric from hot (CSPN). Instead, we demonstrate well modeled by optically thin thermal plasmas. From...
We present results from the most recent set of observations obtained as part Chandra X-ray observatory Planetary Nebula Survey (ChanPlaNS), first comprehensive survey planetary nebulae (PNe) in solar neighborhood (i.e., within ~1.5 kpc Sun). The is designed to place constraints on frequency appearance and range spectral characteristics X-ray-emitting PN central stars evolutionary timescales wind-shock-heated bubbles PNe. ChanPlaNS began with a combined Cycle 12 archive 35 continued via 14...
Abstract We have performed a comprehensive study of the UV emission detected from asymptotic giant branch (AGB) stars by Galaxy Evolution Explorer ( GALEX ). Of 468 AGB in our sample, 316 were observed . In near-UV (NUV) bandpass <?CDATA ${\lambda }_{\mathrm{eff}}\sim 2310\,\mathring{\rm A} $?> ), 179 and 137 not detected. Only 38 far-UV (FUV) 1528\,\mathring{\rm find that NUV is correlated with optical to near-infrared emission, leading higher detection fractions among brightest, hence...
Context. This is the first publication from DEATHSTAR project. The overall goal of project to reduce uncertainties observational estimates mass-loss rates evolved stars on Asymptotic Giant Branch (AGB). Aim. aim in this constrain sizes 12 CO emitting region circumstellar envelopes around 42 mostly southern AGB stars, which 21 are M-type and C-type, using Atacama Compact Array (ACA) at Large Millimeter/submillimeter Array. symmetry outflows also investigated. Methods. Line emission J = 2→1...
Abstract We report on the detection and analysis of extended X-ray emission by Chandra Observatory stemming from 2006 eruption recurrent nova RS Oph. The was detected 1254 1927 days after start is consistent with a bipolar flow oriented in East–West direction sky opening angles approximately 70°. length both lobes appeared to expand 1.″3 2009 2.″0 2011, suggesting projected expansion rate 1.1 ± 0.1 mas day −1 an velocity 4600 km s ( D /2.4 kpc) plane sky. This previous estimates optical...
Close binary systems undergoing mass transfer or common envelope interactions can account for the morphological properties of some planetary nebulae. The search close companions in nebulae is hindered by difficulty detecting cool, late-type, main sequence with hot pre-white dwarf primaries. However, models PN progenitor predict that accretion tidal induce rapid rotation companion, leading to X-ray-emitting coronae. To test such models, we have searched for, and detected, X-ray emission from...
This is the first of a series investigations into far-IR characteristics 11 planetary nebulae (PNs) under Herschel Space Observatory Open Time 1 program, Planetary Nebula Survey (HerPlaNS). Using HerPlaNS data set, we look PN energetics and variations physical conditions within target nebulae. In present work, provide an overview survey, acquisition processing, resulting products. We perform (1) PACS/SPIRE broadband imaging to determine spatial distribution cold dust component in PNs (2)...
Certain planetary nebulae contain shells, filaments, or globules of cold gas and dust whose heating chemistry are likely driven by UV X-ray emission from their central stars wind-collision-generated shocks. We present the results a survey molecular line in 88-236 GHz range nine nearby (<1.5 kpc) spanning luminosities, using 30 m telescope Institut de Radioastronomie Millimetrique. Rotational transitions thirteen molecules, including CO isotopologues chemically important trace species, were...
We present the analysis of archival XMM-Newton and Chandra observations CH Cyg, one most studied symbiotic stars (SySts). The combination high-resolution RGS HETG X-ray spectra allowed us to obtain reliable estimates chemical abundances corroborate presence multi-temperature X-ray-emitting gas. Spectral fitting medium-resolution MOS (MOS1+MOS2) spectrum required use an additional component not seen in previous studies order fit 2.0-4.0 keV energy range. Detailed spectral modelling data...
We report the first detections of OH$^+$ emission in planetary nebulae (PNe). As part an imaging and spectroscopy survey 11 PNe far-IR using PACS SPIRE instruments aboard Herschel Space Observatory, we performed a line these over entire spectral range between 51 672$\mu$m to look for new detections. rotational lines at 152.99, 290.20, 308.48, 329.77$\mu$m were detected spectra three nebulae: NGC 6445, 6720, 6781. Excitation temperatures column densities derived from are 27 47 K...
We present the results of a comprehensive, near-UV-to-near-IR Hubble Space Telescope WFC3 imaging study young planetary nebula (PN) NGC 6302, archetype class extreme bi-lobed, pinched-waist PNe that are rich in dust and molecular gas. The new emission-line image suite clearly defines dusty toroidal equatorial structure bisects 6302's polar lobes, fine structures (clumps, knots, filaments) within lobes. most striking aspect is bright, S-shaped 1.64 micron [Fe II] emission traces southern...
We report the serendipitous detection of planetary nebula NGC 5315 by Chandra X-ray Observatory. The imaging spectroscopy results indicate that X-rays from this PN, which harbors a Wolf-Rayet (WR) central star, emanate T_X ~ 2.5x10^6 K plasma generated via same wind-wind collisions have cleared compact (~8000 AU radius) cavity within nebula. inferred luminosity is ~2.5x10^{32} erg s^{-1} (0.3-2.0 keV), placing object among most luminous such ``hot bubble'' sources yet detected PNe. With...
We explore the possibility that GSC 07396–00759 (spectral type M1e) is a widely separated (∼282, or projected separation ∼12,350 AU) companion to "old" (age ∼12 Myr) classical T Tauri binary system V4046 Sgr AB, as suggested by proximity and similar space motions of two systems. If systems are equidistant coeval, then 07396–00759, like must be spectroscopic with nearly equal-mass components, at least ∼8 Myr old. Analysis serendipitous Chandra X-ray grating spectrum light curve well...
We present the results of Chandra X-ray Observatory (CXO) observations planetary nebulae (PNs) NGC 40 and Hen 2-99. Both PNs feature late-type Wolf-Rayet central stars that are presently driving fast ~1000 km/s, massive winds into denser, slow-moving (~10 km/s) material ejected during recently terminated asymptotic giant branch (AGB) evolutionary phases. Hence, these provide key tests models wind-wind interactions in PNs. In 40, we detect faint, diffuse emission distributed within a partial...
Radio, infrared, and optical observations of the 2006 eruption symbiotic recurrent nova RS Ophiuchi showed that explosion produced non-spherical ejecta. Some this ejected material was in form bipolar jets to east west central source. Here we describe X-ray taken with Chandra Observatory one a half years after beginning outburst reveal narrow, extended structure position angle approximately 300° (east north). Although orientation feature image is consistent readout direction CCD detector,...
The early-K star T Cha, a member of the nearby (D ≈ 100 pc) Cha Association, is relatively "old" (age ∼ 7 Myr) Tauri that still sporadically accreting from an orbiting disk whose inner regions are now evidently being cleared by close, substellar companion. We report identification, via analysis proper motions, serendipitous X-ray imaging spectroscopy, and follow-up optical new Association very likely low-mass companion to at projected separation ∼38 kAU. combined spectroscopy data indicate...
Stars over a wide range of masses and evolutionary stages are nowadays known to emit X-rays. This X-ray emission is unique probe the most energetic phenomena occurring in circumstellar environment these stars, provides precious insight on magnetic or hydrodynamic shocks. Owing its large collecting area, Athena+ will open up an entirely new window phenomena. Indeed, not only allow us study many more objects with unprecedented spectral resolution, but also pioneer dynamics via time-resolved...
The iconic planetary nebula (PN) NGC 7027 is bright, nearby (D ~ 1 kpc), highly ionized, intricately structured, and well observed. This hence an ideal case study for understanding PN shaping evolution processes. Accordingly, we have conducted a comprehensive imaging survey of comprised twelve HST Wide Field Camera 3 images in narrow-band continuum filters spanning the wavelength range 0.243--1.67 microns. resulting panchromatic image suite reveals spatial distributions emission lines...
We seek to establish the presence and properties of gas in circumstellar disk orbiting T Cha, a nearby (d~110 pc), relatively evolved (age ~5-7 Myr) yet actively accreting 1.5 Msun Tauri star. used APEX 12 m radiotelescope search for submillimeter molecular emission from Cha disk, we reanalyzed archival XMM-Newton spectroscopy ascertain intervening absorption due along line sight star (N_H). detected rotational transitions 12CO, 13CO, HCN, CN HCO+ disk. The 12CO appears display double-peaked...
Context. Magnetic fields have been measured around asymptotic giant branch (AGB) stars of all chemical types using maser polarization observations. If present, a large-scale magnetic field would lead to X-ray emission, which should be observable current observatories.
Abstract We present an analysis of a second observation the young planetary nebula (PN) NGC 7027 by Chandra X-ray Observatory . This latest 59.2 ks exposure with ACIS-S was acquired approximately 14 years after initial 18.2 observation, and improved photon statistics allow us to perform detailed spatial spectral emission. Comparison multiwavelength imaging reveals strong anti-correlation between extinction across soft-band Dissecting emission into low- high-extinction regions results in more...