Search Publications
The Source Region of Coronal Mass Ejections
Lara, Alejandro
We use the large database of coronal mass ejections (CMEs) observed by SOHO LASCO during solar cycle 23 to statistically obtain information about the source regions of CMEs. By determining the functional form of the position angle (P.A.) distribution, we are able to construct a random set of CME direction vectors (DVCME) under the follo…
Evidence for a Photoevaporated Circumbinary Disk in Orion
Robberto, M.; Da Rio, N.; Ricci, L. +1 more
We have found a photoevaporated disk in the Orion Nebula that includes a wide binary. HST ACS observations of the proplyd 124-132 show two pointlike sources separated by 0.15'', or about 60 AU at the distance of Orion. The two sources have nearly identical I and z magnitudes. We analyze the brightest component, source N, comparing the observed mag…
The Radio Signature of Magnetic Reconnection for the M-Class Flare of 2004 November 1
Ji, Haisheng; Huang, Guangli; Wu, Guiping
In this Letter, we present radio diagnostics for the magnetic field and the density distribution of nonthermal electrons in the microwave source of the M1.1 flare of 2004 November 1. We calculate the nonthermal gyrosynchrotron radiation using observations made at the Nobeyama Radio Observatory to get the longitudinal magnetic field and the magnitu…
On the Formation of Perseus OB1 at High Galactic Latitudes
Lim, Jeremy; Lee, Hsu-Tai
The Per OB1 association, which contains the remarkable double cluster h and χ Per, is unusual in not having a giant molecular cloud in its vicinity. We show from Hipparcos data that the luminous members of this association exhibit a bulk motion away from the Galactic plane, such that their average velocity increases with height above the Galactic …
Comparison of High-Resolution TRACE Data to Spectroscopic CDS Data for Temperature Determination
Walsh, R. W.; Noglik, J. B.; Cirtain, J.
In this paper we aim to measure the temperature along a specific coronal loop feature which is located in an active region on the western solar limb. The data are taken from Joint Observing Program 146 and consist of high-cadence TRACE triple-filter images coinciding with sparse raster Coronal Diagnostic Spectrometer (CDS) spectroscopic data. The …
HST NICMOS Observations of Fast Infrared Flickering in the Microquasar GRS 1915+105
Patel, Shannon G.; Remillard, Ronald; Pooley, Guy G. +3 more
We report infrared observations of the microquasar GRS 1915+105 using the NICMOS instrument of the Hubble Space Telescope during nine visits in 2003 April-June. During epochs of high X-ray/radio activity near the beginning and end of this period, we find that the 1.87 µm infrared flux is generally low (~2 mJy) and relatively steady. However,…
The Spitzer View of Low-Metallicity Star Formation. II. Mrk 996, a Blue Compact Dwarf Galaxy with an Extremely Dense Nucleus
Hunt, Leslie K.; Thuan, Trinh X.; Izotov, Yuri I.
We present new Spitzer, UKIRT, and MMT observations of the blue compact dwarf galaxy (BCD) Mrk 996, with an oxygen abundance of 12 + log (O/H) = 8.0. This galaxy possesses an extraordinarily dense nuclear star-forming region, with a central density of ~106 cm-3, a very red color J - K = 1.8, broad- and narrow-line components,…
The Very Soft X-Ray Spectrum of the Double Pulsar System J0737-3039
Camilo, F.; Rea, N.; Possenti, A. +5 more
We present the results of an 80 ks Chandra ACIS-S observation of the double pulsar system J0737-3039. Furthermore, we report on spectral, spatial and timing analysis of the combined X-ray observations performed so far for this system. Fitting a total of ~1100 photons, we show that the X-ray spectrum of the J0737-3039 system is very soft, and not s…
The Structure of Active Merger Remnant NGC 6240 from IRAC Observations
Fazio, Giovanni G.; Wang, Zhong; Karovska, Margarita +1 more
NGC 6240 is a rare object in the local universe: an active merger remnant viewed at the point of merging where two active galactic nuclei are visible. We present IRAC data of this object, providing high-sensitivity maps of the stellar and PAH distribution in this complicated system. We use photometry to analyze the variation in these distributions…
Short-Lived Absorptive Type III-like Microwave Bursts as a Signature of Fragmented Electron Injections
Chen, Bin; Yan, Yihua
In this paper, we devote ourselves to interpreting the short-lived absorptive type III-like microwave bursts in the 2006 December 13 flare event observed with high temporal and spectral resolutions (8 ms and 10 MHz) by the Chinese Solar Broadband Radio Spectrometer (SBRS/Huairou) at 2.6-3.8 GHz. In the decimeter-centimeter wavelength range, we fir…