Search Publications
Detection of Plasma Fluctuations in White-light Images of the Outer Solar Corona: Investigation of the Spatial and Temporal Evolution
Romano, P.; Antonucci, E.; Spadaro, D. +2 more
This work focuses on the first results from the identification and characterization of periodic plasma density fluctuations in the outer corona, observed in STEREO-A COR1 white-light image time series. A two-dimensional reconstruction of the spatial distribution and temporal evolution of the coronal fluctuation power has been performed over the wh…
Does a Scaling Law Exist between Solar Energetic Particle Events and Solar Flares?
Kahler, S. W.
Among many other natural processes, the size distributions of solar X-ray flares and solar energetic particle (SEP) events are scale-invariant power laws. The measured distributions of SEP events prove to be distinctly flatter, i.e., have smaller power-law slopes, than those of the flares. This has led to speculation that the two distributions are…
Rapid Evolution of the Solar Atmosphere during the Impulsive Phase of a Microflare Observed with the Extreme-ultraviolet Imaging Spectrometer aboard Hinode: Hints of Chromospheric Magnetic Reconnection
Brosius, Jeffrey W.
We obtained rapid cadence (11.2 s) EUV stare spectra of a solar microflare with the Extreme-ultraviolet Imaging Spectrometer aboard Hinode. The intensities of lines formed at temperatures too cool to be found in the corona brightened by factors around 16 early during this event, indicating that we observed a site of energy deposition in the chromo…
X-Ray Transients in the Advanced LIGO/Virgo Horizon
Kanner, Jonah; Baker, John; Blackburn, Lindy +4 more
Advanced LIGO and Advanced Virgo will be all-sky monitors for merging compact objects within a few hundred megaparsecs. Finding the electromagnetic counterparts to these events will require an understanding of the transient sky at low redshift (z < 0.1). We performed a systematic search for extragalactic, low redshift, transient events in the X…
Characterization of a Sample of Intermediate-type AGNs. I. Spectroscopic Properties and Serendipitous Discovery of New Dual AGNs
Méndez-Abreu, Jairo; Benítez, Erika; Cruz-González, Irene +6 more
A sample of 10 nearby intermediate-type active galactic nuclei (AGNs) drawn from the Sloan Digital Sky Survey is presented. The aim of this work is to provide estimations of the black hole (BH) mass for the sample galaxies from the dynamics of the broad-line region. For this purpose, a detailed spectroscopic analysis of the objects was done. Using…
The Parsec-scale Environment and the Evolutionary Status of MWC 349A
Strelnitski, Vladimir; Bieging, John H.; Hora, Joseph +4 more
We report on a study of the ~10' (~5 pc in projection) environs of the peculiar, high-luminosity emission-line star MWC 349A in the IR, radio, and visible domains. Besides the recently discovered X-shaped, arcmin-scale IR nebula centered on MWC 349A ("X nebula"), with the kinematic age of ~104 yr, we identify several young objects point…
Study of Magnetic Helicity Injection in the Active Region NOAA 9236 Producing Multiple Flare-associated Coronal Mass Ejection Events
Chae, Jongchul; Park, Sung-Hong; Kumar, Pankaj +6 more
To better understand a preferred magnetic field configuration and its evolution during coronal mass ejection (CME) events, we investigated the spatial and temporal evolution of photospheric magnetic fields in the active region NOAA 9236 that produced eight flare-associated CMEs during the time period of 2000 November 23-26. The time variations of …
Broad N2H+ Emission toward the Protostellar Shock L1157-B1
Podio, L.; Codella, C.; Ceccarelli, C. +8 more
We present the first detection of N2H+ toward a low-mass protostellar outflow, namely, the L1157-B1 shock, at ~0.1 pc from the protostellar cocoon. The detection was obtained with the IRAM 30 m antenna. We observed emission at 93 GHz due to the J = 1-0 hyperfine lines. Analysis of this emission coupled with HIFI CHESS multili…
Masses and Distance of the Young Binary NTTS 045251+3016
Franz, O. G.; Prato, L.; Schaefer, G. H. +4 more
As part of our continuing campaign to measure the masses of pre-main-sequence (PMS) stars dynamically and thus to assess the reliability of the discrepant theoretical calculations of contraction to the main sequence, we present new results for NTTS 045251+3016, a visual and double-lined spectroscopic binary in the Taurus star-forming region (SFR).…
Interstellar Abundances toward X Per, Revisited
Smith, Randall K.; Valencic, Lynne A.
The nearby X-ray binary X Per (HD 24534) provides a useful beacon with which to examine dust grain types and measure elemental abundances in the local interstellar medium (ISM). The absorption features of O, Fe, Mg, and Si along this line of sight were measured using spectra from the Chandra X-Ray Observatory's LETG/ACIS-S and XMM-Newton's RGS ins…