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Chemical evolution of the HC3N and N2H+ molecules in dense cores of the Vela C giant molecular cloud complex
Sanhueza, Patricio; Choi, Minho; Tatematsu, Ken'ichi +5 more
We have observed the HC3N(J = 10-9) and N2H+ (J = 1-0) lines toward the Vela C molecular clouds with the Mopra 22 m telescope to study the chemical characteristics of dense cores. The intensity distributions of these molecules are similar to each other at an angular resolution of 53″, corresponding to 0.19 pc, sugg…
Distribution of hydrogen and oxygen ion species in the plasmasheet
Wang, Jing; Cao, Jinbin; Liu, Wenlong
In this paper, using data obtained by Cluster 4 satellite from 2001 to 2012, we statistically investigate the spatial distributions of H+ and O+ in the magnetotail plasmasheet and their relation with geomagnetic indices. Our work outlines the existence of two regions with enhanced O+ concentration in the tail plasm…
Young Stellar Populations in MYStIX Star-forming Regions: Candidate Protostars
Feigelson, Eric D.; Povich, Matthew S.; Getman, Konstantin V. +2 more
The Massive Young Star-Forming Complex in Infrared and X-ray (MYStIX) project provides a new census on stellar members of massive star-forming regions within 4 kpc. Here the MYStIX Infrared Excess catalog and Chandra-based X-ray photometric catalogs are mined to obtain high-quality samples of Class I protostars using criteria designed to reduce ex…
Broad-band X-ray emission and the reality of the broad iron line from the neutron star-white dwarf X-ray binary 4U 1820-30
Misra, R.; Dewangan, G. C.; Mondal, Aditya S. +3 more
Broad relativistic iron lines from neutron star X-ray binaries are important probes of the inner accretion disc. The X-ray reflection features can be weakened due to strong magnetic fields or very low iron abundances such as is possible in X-ray binaries with low mass, first generation stars as companions. Here, we investigate the reality of the b…
Are There Two Distinct Solar Energetic Particle Releases in the 2012 May 17 Ground Level Enhancement Event?
Li, Gang; Ding, Liu-Guan; Jiang, Yong
We examine ion release times in the solar vicinity for the 2012 May 17 Ground Level Enhancement event using the velocity dispersion analysis method. In situ energetic proton data from Solar and Heliospheric Observatory (SOHO)/Energetic and Relativistic Nuclei and Electron and Geostationary Operational Environmental Satellite are used. We find two …
First Simultaneous Views of the Axial and Lateral Perspectives of a Coronal Mass Ejection
Balmaceda, L.; Cremades, H.; Cabello, I. +1 more
The different appearances exhibited by coronal mass ejections (CMEs) are believed to be in part the result of different orientations of their main axis of symmetry, consistent with a flux-rope configuration. There are observational reports of CMEs seen along their main axis (axial perspective) and perpendicular to it (lateral perspective), but no …
Solar-cycle variation of the rotational shear near the solar surface
Schou, J.; Gizon, L.; Barekat, A.
Context. Helioseismology has revealed that the angular velocity of the Sun increases with depth in the outermost 35 Mm of the Sun. Recently, we have shown that the logarithmic radial gradient (dlnΩ/dlnr) in the upper 10 Mm is close to -1 from the equator to 60° latitude.
Aims: We aim to measure the temporal variation of the rotational shear o…
An Apparent Precessing Helical Outflow from a Massive Evolved Star: Evidence for Binary Interaction
Morris, M. R.; Mills, E. A. C.; Ressler, M. E. +3 more
Massive, evolved stars play a crucial role in the metal enrichment, dust budget, and energetics of the interstellar medium; however, the details of their evolution are uncertain because of their rarity and short lifetimes before exploding as supernovae. Discrepancies between theoretical predictions from single-star evolutionary models and observat…
Template matching method for the analysis of interstellar cloud structure
Juvela, M.
Context. The structure of interstellar medium can be characterised at large scales in terms of its global statistics (e.g. power spectra) and at small scales by the properties of individual cores. Interest has been increasing in structures at intermediate scales, resulting in a number of methods being developed for the analysis of filamentary stru…
The Metallicity Evolution of Blue Compact Dwarf Galaxies from the Intermediate Redshift to the Local Universe
Fang, Guanwen; Kong, Xu; Lian, Jianhui +2 more
We present oxygen abundance measurements for 74 blue compact dwarf (BCD) galaxies in the redshift range of [0.2, 0.5] using the strong-line method. The spectra of these objects are taken using Hectospec on the Multiple Mirror Telescope. More than half of these BCDs had dust attenuation corrected using the Balmer decrement method. For comparison, w…