Search Publications
First Taste of Hot Channel in Interplanetary Space
Chen, Y.; Song, H. Q.; Cheng, X. +3 more
A hot channel (HC) is a high temperature (∼10 MK) structure in the inner corona first revealed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. Eruptions of HCs are often associated with flares and coronal mass ejections (CMEs). Results of previous studies have suggested that an HC is a good proxy for a magnetic flux ro…
Co-spatial Long-slit UV/Optical Spectra of Ten Galactic Planetary Nebulae with HST/STIS. II. Nebular Models, Central Star Properties, and He+CNO Synthesis
Balick, B.; Corradi, R. L. M.; Dufour, R. J. +5 more
The goal of the present study is twofold. First, we employ new HST/STIS spectra and photoionization modeling techniques to determine the progenitor masses of eight planetary nebulae (IC 2165, IC 3568, NGC 2440, NGC 3242, NGC 5315, NGC 5882, NGC 7662, and PB 6). Second, for the first time we are able to compare each object’s observed nebular abunda…
The Volatile Composition of Comet C/2003 K4 (LINEAR) at Near-IR Wavelengths—Comparisons with Results from the NanÇay Radio Telescope and from the Odin, Spitzer, and SOHO Space Observatories
Villanueva, G. L.; Paganini, L.; Mumma, M. J. +2 more
We observed comet C/2003 K4 (LINEAR) using NIRSPEC at the Keck Observatory on UT 2004 November 28, when the comet was at 1.28 AU from the Sun (post-perihelion) and 1.38 AU from Earth. We detected six gaseous species (H2O, OH*, C2H6, CH3OH, CH4, and HCN) and obtained upper limits for three othe…
A New Sample of Obscured AGNs Selected from the XMM-Newton and AKARI Surveys
Oyabu, Shinki; Gandhi, Poshak; Awaki, Hisamitsu +4 more
We report a new sample of obscured active galactic nuclei (AGNs) selected from the XMM-Newton serendipitous source and AKARI point-source catalogs. We match X-ray sources with infrared (18 and 90 µm) sources located at | b| \gt 10^\circ to create a sample consisting of 173 objects. Their optical classifications and absorption column densitie…
Probing Magnetic Fields at the Base of the Solar Convection Zone with Meridional Flows
Liang, Zhi-Chao; Chou, Dean-Yi
Solar magnetic fields are responsible for most of the activities on the Sun. Many theories predict that it is generated by a dynamo near the base of the convection zone (BCZ), located at 0.71{R}⊙ . In this study, we use the solar-cycle variations of the meridional flow to probe magnetic field variations near the BCZ. A helioseismic time…
Seed Population in Large Solar Energetic Particle Events and the Twin-CME Scenario
Li, Gang; Ding, Liu-Guan; Le, Gui-Ming +2 more
It has recently been suggested that large solar energetic particle (SEP) events are often caused by twin coronal mass ejections (CMEs). In the twin-CME scenario, the preceding CME provides both an enhanced turbulence level and enhanced seed population at the main CME-driven shock. In this work, we study the effect of the preceding CMEs on the seed…
An Extreme High-velocity Bipolar Outflow in the Pre-planetary Nebula IRAS 08005-2356
Sahai, R.; Patel, N. A.
We report interferometric mapping of the bipolar pre-planetary nebula IRAS 08005-2356 (I 08005) with an angular resolution of ∼1″-5″, using the Submillimeter Array, in the 12CO J = 2-1, 3-2, 13CO J = 2-1, and SiO J = 5-4 (v = 0) lines. Single-dish observations, using the SMT 10 m, were made in these lines as well as in the CO…
Near-infrared Extinction due to Cool Supernova Dust in Cassiopeia A
Koo, Bon-Chul; Lee, Jae-Joon; Moon, Dae-Sik +1 more
We present the results of extinction measurements toward the main ejecta shell of the Cassiopeia A supernova (SN) remnant using the flux ratios between the two near-infrared (NIR) [Fe ii] lines at 1.26 and 1.64 µm. We find a clear correlation between the NIR extinction (E(J-H)) and the radial velocity of ejecta knots, showing that redshifted…
Optical Spectroscopy of Supernova Remnants in M81 and M82
Park, Byeong-Gon; Hwang, Narae; Koo, Bon-Chul +7 more
We present spectroscopy of 28 supernova remnant (SNR) candidates as well as one H ii region in M81 and two SNR candidates in M82. Twenty-six of the M81 candidates turn out to be genuine SNRs, and two in M82 may be shocked condensations in the galactic outflow or SNRs. The distribution of [N ii]/Hα ratios of M81 SNRs is bimodal. M81 SNRs are divide…
Ages of Star Clusters in the Tidal Tails of Merging Galaxies
Whitmore, B. C.; Chandar, R.; Mulia, A. J.
We study the stellar content in the tidal tails of three nearby merging galaxies, NGC 520, NGC 2623, and NGC 3256, using BVI imaging taken with the Advanced Camera for Surveys on board the Hubble Space Telescope. The tidal tails in all three systems contain compact and fairly massive young star clusters, embedded in a sea of diffuse, unresolved st…