A5047634159- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Geomagnetism and Paleomagnetism Studies
- Geophysics and Gravity Measurements
- Gamma-ray bursts and supernovae
- Solar Radiation and Photovoltaics
- Oil, Gas, and Environmental Issues
- Earthquake Detection and Analysis
- Spacecraft and Cryogenic Technologies
- Spacecraft Design and Technology
- Calibration and Measurement Techniques
- Astronomical Observations and Instrumentation
- Nuclear reactor physics and engineering
- Atmospheric Ozone and Climate
- Dark Matter and Cosmic Phenomena
- Global Energy and Sustainability Research
- Meteorological Phenomena and Simulations
- Magnetic confinement fusion research
- Photovoltaic System Optimization Techniques
- Astronomy and Astrophysical Research
- Reservoir Engineering and Simulation Methods
- History and Developments in Astronomy
- Tropical and Extratropical Cyclones Research
Center for Astrophysics Harvard & Smithsonian
2015-2024
Smithsonian Astrophysical Observatory
2007-2023
Marshall Space Flight Center
2007-2023
National Astronomical Observatory of Japan
2007-2023
Japan Aerospace Exploration Agency
2007-2023
University of California, Berkeley
2023
Lockheed Martin (United States)
2023
New Jersey Institute of Technology
2023
Southwest Research Institute
2023
Princeton University
2023
The Interface Region Imaging Spectrograph (IRIS) small explorer spacecraft provides simultaneous spectra and images of the photosphere, chromosphere, transition region, corona with 0.33-0.4 arcsec spatial resolution, 2 s temporal resolution 1 km/s velocity over a field-of-view up to 175 x arcsec. IRIS was launched into Sun-synchronous orbit on 27 June 2013 using Pegasus-XL rocket consists 19-cm UV telescope that feeds slit-based dual-bandpass imaging spectrograph. obtains in passbands from...
Coronal magnetic fields are dynamic, and field lines may misalign, reassemble, release energy by means of reconnection. Giant releases generate solar flares coronal mass ejections and, on a smaller scale, produce x-ray jets. Hinode observations polar holes reveal that jets have two distinct velocities: one near the Alfvén speed (∼800 kilometers per second) another sound (200 second). Many more were seen than been reported previously; we detected an average 10 events hour up to these speeds,...
As the interface between Sun’s photosphere and corona, chromosphere transition region play a key role in formation acceleration of solar wind. Observations from Interface Region Imaging Spectrograph reveal prevalence intermittent small-scale jets with speeds 80 to 250 kilometers per second narrow bright network lanes this region. These have lifetimes 20 seconds widths ≤300 kilometers. They originate regions, often preceded by footpoint brightenings accompanied transverse waves amplitudes ~20...
The solar atmosphere was traditionally represented with a simple one-dimensional model. Over the past few decades, this paradigm shifted for chromosphere and corona that constitute outer atmosphere, which is now considered dynamic structured envelope. Recent observations by IRIS (Interface Region Imaging Spectrograph) reveal it difficult to determine what up down even in cool 6000-K photosphere just above surface: region hosts pockets of hot plasma transiently heated almost 100,000 K. energy...
The physical processes causing energy exchange between the Sun's hot corona and its cool lower atmosphere remain poorly understood. chromosphere transition region (TR) form an interface surface that is highly sensitive to coronal heating mechanism. High-resolution observations with Interface Region Imaging Spectrograph (IRIS) reveal rapid variability (~20 60 seconds) of intensity velocity on small spatial scales (≲500 kilometers) at footpoints dynamic loops. are consistent numerical...
Supra-arcade downflows (SADs) have been observed with Yohkoh/SXT (soft X-rays (SXR)), TRACE (extreme ultra-violet (EUV)), SoHO/LASCO (white light), SoHO/SUMER (EUV spectra), and Hinode/XRT (SXR). Characteristics such as low emissivity trajectories which slow they reach the top of arcade are consistent post-reconnection magnetic flux tubes retracting from a reconnection site high in corona until lower-energy configuration. Viewed perpendicular angle, SADs should appear shrinking loops rather...
We address the formation of three-dimensional nullpoint topologies in solar corona by combining Hinode/X-ray Telescope (XRT) observations a small dynamic limb event, which occurred beside non-erupting prominence cavity, with (3D) zero-β magnetohydrodynamics (MHD) simulation. To this end, we model boundary-driven "kinematic" emergence compact, intense, and uniformly twisted flux tube into potential field arcade that overlies weakly coronal rope. The expansion emerging gives rise to at...
The solar chromosphere and transition region (TR) form an interface between the Sun's surface its hot outer atmosphere. There, most of nonthermal energy that powers atmosphere is transformed into heat, although detailed mechanism remains elusive. High-resolution (0.33-arc second) observations with NASA's Interface Region Imaging Spectrograph (IRIS) reveal a TR are replete twist or torsional motions on sub-arc second scales, occurring in active regions, quiet Sun coronal holes alike. We...
Magnetic reconnection is believed to be the dominant energy release mechanism in solar flares. The standard flare model predicts both downward and upward outflow plasmas with speeds close coronal Alfvén speed. Yet, spectroscopic observations of such outflows, especially downflows, are extremely rare. With newly launched Interface Region Imaging Spectrograph (IRIS), we report detection a greatly redshifted (∼125 km s−1 along line sight) Fe xxi 1354.08 Å emission ∼100 nonthermal width at site...
Sympathetic eruptions on the Sun have been observed for several decades, but mechanisms by which one eruption can trigger another remain poorly understood. We present a three-dimensional MHD simulation that suggests two possible magnetic sympathetic eruptions. consider configuration contains coronal flux ropes located within pseudo-streamer and rope next to it. A sequence of is initiated triggering streamer. The expansion leads consecutive reconnection events, each triggers removing...
With observations from the Interface Region Imaging Spectrograph (IRIS), we track complete evolution of $\sim$11 MK evaporation flows in an M1.1 flare on 2014 September 6 and X1.6 10. These hot flows, as indicated by blueshifted Fe~{\sc{xxi}}~1354.08\AA{}~line, evolve smoothly with a velocity decreasing exponentially $\sim$200~km~s$^{-1}$ to almost stationary within few minutes. We find good correlation between flow energy deposition rate represented hard X-Ray flux observed Reuven Ramaty...
We report on observations of recurrent jets by instruments onboard the Interface Region Imaging Spectrograph (IRIS), Solar Dynamics Observatory (SDO) and Hinode spacecrafts. Over a 4-hour period July 21st 2013, coronal were observed to emanate from NOAA Active 11793. FUV spectra probing plasma at transition region temperatures show evidence oppositely directed flows with components reaching Doppler velocities +/- 100 km/s. Raster maps using Si IV line all four have helical motion same sense....
Determining the 3D coronal magnetic field is a critical, but extremely difficult problem to solve. Since different types of multiwavelength data probe aspects field, ideally these should be used together validate and constrain specifications that field. Such task requires ability create observable quantities at range wavelengths from distribution associated plasma -- i.e., perform forward calculations. In this paper we describe capabilities FORWARD SolarSoft IDL package, uniquely...
The heating of the outer solar atmospheric layers, i.e., transition region and corona, to high temperatures is a long standing problem in (and stellar) physics. Solutions have been hampered by an incomplete understanding magnetically controlled structure these regions. spatial temporal resolution observations with Interface Region Imaging Spectrograph (IRIS) at limb reveal plethora short, low lying loops or loop segments transition-region that vary rapidly, on timescales minutes. We argue...
Abstract Hinode is Japan’s third solar mission following Hinotori (1981–1982) and Yohkoh (1991–2001): it was launched on 2006 September 22 in operation currently. carries three instruments: the Solar Optical Telescope, X-Ray EUV Imaging Spectrometer. These instruments were built under international collaboration with National Aeronautics Space Administration UK Science Technology Facilities Council, its has been contributed to by European Agency Norwegian Center. After describing satellite...
The Interface Region Imaging Spectrograph (IRIS) has been obtaining near- and far-ultraviolet images spectra of the solar atmosphere since July 2013. unique combination near at subarcsecond resolution high cadence allows tracing mass energy through critical interface between surface corona or wind. IRIS enabled research into fundamental physical processes thought to play a role in low such as ion-neutral interactions, magnetic reconnection, generation, propagation, dissipation various types...
Abstract Current state-of-the-art spectrographs cannot resolve the fundamental spatial (subarcseconds) and temporal (less than a few tens of seconds) scales coronal dynamics solar flares eruptive phenomena. The highest-resolution data to date are based on imaging, which is blind many processes that drive energetics dynamics. As shown by Interface Region Imaging Spectrograph for low atmosphere, we need high-resolution spectroscopic measurements with simultaneous imaging understand dominant...
Following the eruption of a filament from flaring active region, sunward-flowing voids are often seen above developing post-eruption arcades. First discovered using soft X-ray telescope aboard Yohkoh, these supra-arcade downflows (SADs) now an expected observation extreme ultra-violet (EUV) and coronal imagers spectrographs (e.g, TRACE, SOHO/SUMER, Hinode/XRT, SDO/AIA). Observations made prior to operation AIA suggested that plasma (which in contrast bright, high-temperature associated with...
We present a three-dimensional density model of coronal prominence cavities, and morphological fit that has been tightly constrained by uniquely well-observed cavity. Observations were obtained as part an International Heliophysical Year campaign instruments from variety space- ground-based observatories, spanning wavelengths radio to soft X-ray integrated white light. From these data it is clear the cavity limb manifestation longitudinally extended polar-crown filament channel, region low...
We present observations of hot plasma from solar eruptions recorded by the Atmospheric Imaging Assembly (AIA) on Solar Dynamics Observatory. AIA is first narrowband instrument capable taking images in 5–15 MK range. find that there are structures above flare loops, and they typically more diffuse nebulous than well-defined loops. Because response, high sensitivity, spatial resolution AIA, these supra-arcade visible exquisite detail, particularly 131 Å 94 channels. In one event, a C4.9...
We investigate coronal energy flow during a simulated mass ejection (CME). model the CME in context of global corona using 2.5D numerical MHD code spherical coordinates that includes heating, thermal conduction, and radiative cooling equation. The simulation domain extends from 1 to 20 Rs . To our knowledge, this is first attempt apply detailed diagnostics flare/CME when these important terms are considered equations. find conservation properties quite good, conserving within 4% for entire...
We present the first results of sunspot oscillations from observations by Interface Region Imaging Spectrograph. The strongly nonlinear oscillation is identified in both slit-jaw images and spectra several emission lines formed transition region chromosphere. apply a single Gaussian fit to profiles Mgii 2796.35 {\AA}, Cii 1335.71 Si iv 1393.76 {\AA} sunspot. intensity change about 30%. Doppler shift reveals sawtooth pattern with an amplitude 10 km/s iv. In umbra lags those 3 12 s,...