Steven Christe [1], S. White [2], S. Krucker [1]
1 Space Sciences Lab, U.C. Berkeley
2 Astronomy Department, University of Maryland.
Presented at AAS/SPD 2009 (link)
Abstract
We present a statistical survey of RHESSI microflares observed in hard X-rays (HXR) with simultaneous observations by the Nobeyama Radio Heliograph at 17 GHz and 34 GHz. These microflares were found using a new flare-finding algorithm designed to search the 6-12 keV count-rate when RHESSI’s full sensitivity was available, in order to find the smallest events. Between March 2002 and March 2007, a total of ~25000 events are identified, of which ~8500 are also observed by Nobeyama at 17 and 34 GHz. We compare HXR and radio fluxes and analyze the relationship statistically. When the events are detected at both wavelengths, the relationship between the lightcurves falls into several classes. Radio and HXR images of a small selection of events are used to investigate the relative locations of the two emissions, and we discuss the physical conditions that affect the relationship between the HXR and radio emission.
Steven Christe [1], L. Glesener [1], S. Krucker [1], B. Ramsey [2], T. Takahashi [3], R. Lin [1]
1 Space Sciences Lab, U.C. Berkeley
2 Marshall Space Flight Center
3 ISAS/JAXA
Presented at AAS/SPD 2009 (link)
Abstract
The Focusing Optics X-ray Solar Imager (FOXSI) is a NASA Low Cost Access to Space sounding rocket payload scheduled for launch late 2010. FOXSI will provide imaging spectroscopy with high sensitivity (~50 times RHESSI) and high dynamic range (~100) in hard X-rays (HXR) up to 15 keV. For the first time, it will be possible to search for nonthermal emission of thermal network flares occurring in the quiet corona in order to determine whether they are similar to active region flares. Additionally, FOXSI will extend the active-region flare distribution to events two orders of magnitude smaller than previously observed and determine their contribution to coronal heating. FOXSI is able to achieve this unprecendeted advance in solar HXR observations through the combination of nested HXR optics developped by the Marshall Space Flight Center and novel silicon strip detectors provided by ISAS Japan. The FOXSI mission will provide HXR spectroscopic imaging with an angular resolution of 12″ (FWHM) and ~1 keV energy resolution. FOXSI will be a pathfinder for the future generation of solar HXR spectroscopic imagers.
Steven Christe [1], K. Watanabe [2], S. Krucker [1]
1 Space Sciences Lab, U.C. Berkeley,
2 ISAS/JAXA, Japan.
Presented at AAS/SPD 2009 (link)
Abstract:
In this study we investigate the relationship between RHESSI flares and white light emission as observed by Hinode/SOT at 3968.6 angstroms (Ca II H line), 4306.4 angstroms (G band), and 4505.1 angstroms(blue continuum) images. The emission mechanism for white light emission in flares is not yet understood though it is believed that emission at these wavelengths originates from the chromosphere, photosphere, and deep photosphere respectively. Using a combination of the official RHESSI flare list and a microflare-finding algorithm, we investigate all RHESSI flares with simultaneous observations by RHESSI and Hinode/SOT (a total of ~200 events). Single event studies suggest that microflares are frequently observed in Ca II H line. Photospheric emission is searched for using the location of the Ca II H line chromospheric emission. We discuss the physical conditions necessary that may affect the relationship between HXR and white light emission.
S. Christe [1], Sam Krucker [1], H. Hudson [1], R. Lin [1]
1 Space Sciences Lab, U.C. Berkeley
Presented at AAS/SPD 2009 (link)
Abstract
We present the first in-depth statistical survey of flare source heights observed by RHESSI between March 2002 and March 2007, a total of 25,705 events. These flares were found using a new flare-finding algorithm designed to search the 6-12 keV count-rate when RHESSI’s full sensitivity was available in order to find the smallest events. Thermal (4-10 keV) and nonthermal (15-25 keV) images were made for all microflares and source centroid locations were found for each event. In order to extract the height information from source positions, a Monte-Carlo model was developed with an assumed source height distribution where height is measured from the photosphere. We find that the best source height model is given by an exponential distribution with a scale height of 2.1 (0.3) Mm and a minimum height of 3.1 (0.3) Mm. Comparing with previously published loop length measurements, we find that the average loop tilt is ~44 degrees as measured from the vertical.
from www.smbc-comics.com.
Phillip Petit, in 1974, walked across the gap between the world trade center towers on a steel cable. Recently watched the very interesting documentary about it, Man on Wire. Apparently the name of the movie refers to the phrase that the NYPD used to described the “incident” in their police report when they arrested him, hilarious!
The Hinode broadband filter imager filters are as follows (fwhm);
- 3883.5 (7) Å CN I
- 3968.5 (3) Å Ca II H
- 4305.0 (8) Å blue continuum
- 5550.5 (4) Å green continuum
- 6684.4 (4) Å red continuum
- 4306.4 (6.3) Å G band
The resolution (keV) of the FOXSI DSSD as a function of temperature
Looming conferences bring such a keen focus to the mind.
Finally updated to a new version of wordpress! Can now updated from my iPhone (which is what I’m doing now). Hoping this will encourage me to update more…knock on wood.
