Search Publications
CAHA/PPAK Integral-field Spectroscopic Observations of M81. II. Testing Photoionization Models in a Spatially Resolved LINER
Li, Zhiyuan; García-Benito, Rubén; Li, Zongnan +1 more
The origin of the low-ionization nuclear emission-line region (LINER) prevalent in local galaxies and its relationship with supermassive black holes have been debated for decades. We perform a comprehensive evaluation of traditional photoionization models against the circumnuclear ionized gas in M81, for which recent CAHA/PPAK integral-field spect…
Temporal Behaviors of Magnetic Helicity Injections by Self and Mutual Sunspot Rotations
Shimizu, Toshifumi; Hasegawa, Takahiro
Magnetic helicity is a physical parameter used to quantify the complexity of magnetic fields, providing an indication of the energy state in the coronal magnetic structure. We investigate the temporal evolution of magnetic helicity and its relationship to the occurrence of a variety of flares in the solar active region NOAA 12297, which was well o…
Sparse Logistic Regression for RR Lyrae versus Binaries Classification
Bono, Giuseppe; Pasquato, Mario; Braga, Vittorio F. +4 more
RR Lyrae (RRL) stars are old, low-mass, radially pulsating variable stars in their core helium burning phase. They are popular stellar tracers and primary distance indicators since they obey well-defined period-luminosity relations in the near-infrared regime. Their photometric identification is not trivial; indeed, RRL star samples can be contami…
A Survey for C II Emission-line Stars in the Large Magellanic Cloud. II. Final Results and the Origin of C II Emission in [WC] Spectra
Massey, Philip; Morrell, Nidia; Neugent, Kathryn F. +2 more
We present the final results of an imaging and spectroscopic search for stars in the Large Magellanic Cloud (LMC) with C II λλ7231, 7236 emission lines. The goal is to identify and study [WC11] stars, the coolest of the low-mass Wolf-Rayet sequence, and a subset of central stars of planetary nebulae where the C II lines are known to be especially …
Reconstructing the Volume Density Profile of Prestellar Cores with the Anisotropic Inverse Abel Transform Method
Zhang, Yapeng; Liu, Zhengdong; An, Weiming +2 more
Most studies of the 3D density structure of prestellar cores have used isotropic evolution models, which are projected into 2D for direct comparison with observation data. In this study, we introduced the anisotropic inverse Abel transform method for reconstructing the 3D volume density profile of prestellar cores. We demonstrated that this approa…
Multiwavelength Study of Dark Globule DC 314.8-5.1: Point-source Identification and Diffuse Emission Characterization
Cheung, C. C.; Stawarz, Ł.; Rocha, W. R. M. +3 more
We present an analysis of multiwavelength observations of the dark globule DC 314.8-5.1, using data from the Gaia optical, Two Micron All Star Survey near-infrared, and Wide-field Infrared Survey Explorer mid-infrared surveys, dedicated imaging with the Spitzer Space Telescope, and X-ray data obtained with the Swift X-Ray Telescope (XRT). The main…
Electrostatic Plasma Wave Excitations at the Interplanetary Shocks
Giacalone, Joe; Fraschetti, Federico; Singh, Manpreet
Over the last few decades, different types of plasma waves (e.g., the ion acoustic waves (IAWs), electrostatic solitary waves, upper/lower hybrid waves, and Langmuir waves) have been observed in the upstream, downstream, and ramp regions of the collisionless interplanetary (IP) shocks. These waves may appear as short-duration (only a few milliseco…
X-Ray Spectroscopy of Interstellar Carbon: Evidence for Scattering by Carbon-bearing Material in the Spectrum of 1ES 1553+113
Paerels, Frits; Staunton, John
Molecules and particles make up ~40%-70% of carbon in the interstellar medium, yet the exact chemical structure of these constituents remains unknown. We present carbon K-shell absorption spectroscopy of the Galactic interstellar medium obtained with the Low Energy Transmission Grating Spectrometer on board the Chandra Observatory that directly ad…
Near-infrared Polarimetry and H2 Emission toward Massive Young Stars: Discovery of a Bipolar Outflow Associated to S235 e2s3
Ray, T. P.; Dewangan, L. K.; Luna, A. +3 more
We present a near-infrared H-band polarimetric study toward the S235 e2s3 protostar, obtained using the POLICAN instrument on the 2.1 m OAGH telescope. The images reveal a bipolar outflow with a total length of about 0.5 pc. The outflow nebulosity presents a high degree of linear polarization (~80%) and reveals a centrosymmetric pattern with the p…
Discovery of an X-Ray Photoionized Optical Nebula and a Radio Nebula Associated with the ULX NGC 4861 X-1
Liu, Jifeng; Gong, Hang; Urquhart, Ryan +5 more
We have conducted long-slit spectroscopic observations and analyzed archival radio data for the ultraluminous X-ray source (ULX) NGC 4861 X-1. Our spectral line analysis unveils NGC 4861 X-1 as the fourth ULX situated within an X-ray photoionized nebula, following three previous findings made approximately two decades ago. Remarkably, we discover …