Search Publications
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…
Quasi-periodic Oscillation of a Coronal Bright Point
Tian, Hui; Banerjee, Dipankar; Samanta, Tanmoy
Coronal bright points (BPs) are small-scale luminous features seen in the solar corona. Quasi-periodic brightenings are frequently observed in the BPs and are generally linked with underlying magnetic flux changes. We study the dynamics of a BP seen in the coronal hole using the Atmospheric Imaging Assembly images, the Helioseismic and Magnetic Im…
On Extreme-ultraviolet Helium Line Intensity Enhancement Factors on the Sun
Curdt, W.; Fludra, A.; Lanzafame, A. C. +3 more
Helium lines in the solar EUV spectrum provide useful diagnostics of the solar atmosphere plasma. Helium is one of the few elements that exhibits strong emission lines formed in the lower transition region, and it is the second most abundant element in the Sun. However, the analysis of helium lines is complicated by their optical thickness and the…