Search Publications
Multiepoch Optical Spectroscopy of the Post-AGB Star HD 161796
Puķītis, Kārlis; Začs, Laimons; Grankina, Aija
The evolutionary rate of the pulsating post-asymptotic giant branch (post-AGB) star HD 161796 was suspected to be high. Spectra of HD 161796 acquired during a time span of 18 yr are analyzed with the main goal of determining the evolutionary increase in temperature and comparing it with the latest post-AGB star evolutionary models. Inspection of t…
Star and Cluster Formation in the Sh2-112 Filamentary Cloud Complex
Chen, Wen Ping; Sun, Yan; Mondal, Soumen +1 more
We present the star formation activity around the emission nebula Sh2-112. At a distance of ~2.1 kpc, this H II complex, itself 3 pc in radius, is illuminated by the massive star (O8 V) BD+45 3216. The associated molecular cloud extends in angular scales of 2.°0 × 0.°83, corresponding to linear sizes of 73 pc by 30 pc, along the Galactic longitude…
S-type Stars Discovered in Medium-resolution Spectra of LAMOST DR9
Luo, A. -Li; Li, Yin-Bi; Wang, Rui +5 more
In this paper, we report on 606 S-type stars identified from Data Release 9 of the LAMOST medium-resolution spectroscopic (MRS) survey; 539 of them are reported for the first time. The discovery of these stars is a three-step process, i.e., selecting with ZrO-band indices greater than 0.25, excluding non-S-type stars with the iterative Support Vec…
Implicit Solar Coronal Magnetohydrodynamic (MHD) Modeling with a Low-dissipation Hybridized AUSM-HLL Riemann Solver
Shen, Fang; Xiang, Changqing; Wang, Haopeng +2 more
In this paper, we develop a 3D implicit single-fluid magnetohydrodynamic (MHD) model to simulate the steady-state solar corona with a wide range of Mach numbers and low plasma β. We employ a low-dissipation advection upstream splitting method (AUSM) to calculate the convective flux in the regions of low Mach numbers for a high resolution, and hybr…
NuSTAR Spectral Analysis beyond 79 keV with Stray Light
Tomsick, J. A.; Wilms, J.; Buisson, D. J. K. +10 more
Due to the structure of the NuSTAR telescope, photons at a large off axis (>1°) can reach the detectors directly (stray light), without passing through the instrument optics. At these off-axis angles NuSTAR essentially turns into a collimated instrument and the spectrum can extend to energies above the Pt K edge (79 keV) of the multilayers, whi…
Power Anisotropy, Dispersion Signature and Turbulence Diffusion Region in the 3D Wavenumber Domain of Space Plasma Turbulence
Verscharen, Daniel; He, Jiansen; Sahraoui, Fouad +4 more
We explore the multifaceted important features of turbulence (e.g., anisotropy, dispersion, and diffusion) in the three-dimensional (3D) wavenumber domain (k ∥, k ⊥,1, k ⊥,2), by employing the k-filtering technique to high-quality measurements of fields and particles from the Magnetospheric Multiscale Mission (MMS)…
Is Fermi 1544-0649 a Misaligned Blazar? Discovering the Jet Structure with Very Long Baseline Interferometry
Zhang, Zhongli; Chen, Wen; Cheng, Xiaopeng +8 more
Fermi J1544-0649 is a transient GeV source first detected during its GeV flares in 2017. Multiwavelength observations during the flaring time demonstrate variability and spectral energy distributions that are typical of a blazar. Other than the flare time, Fermi J1544-0649 is quiet in the GeV band and has looked rather like a quiet galaxy (2MASX J…
CME-related Large Decreases in the Differential Phase Delay of Tianwen-1 DOR Signals
Liu, Kaijun; Guo, Li; He, Qingbao +2 more
Differential phase delay is calculated for the differential one-way range (DOR) signals transmitted by Tianwen-1, the first Chinese Mars spacecraft that entered into the Mars orbit on 2021 February 10. Large decreases in the differential phase delay are identified in the DOR signals received by ground stations on 2021 March 23 and June 18. The dec…
Diagnosing Triggered Star Formation in the Galactic H II region Sh 2-142
Chen, Wen Ping; Gao, Yu; Sun, Yan +2 more
Stars are formed by gravitational collapse, spontaneously or, in some cases under the constructive influence of nearby massive stars, out of molecular cloud cores. Here we present an observational diagnosis of such triggered formation processes in the prominent H II region Sh 2-142, which is associated with the young star cluster NGC 7380, and wit…
Mid-infrared and Maser Flux Variability Correlation in Massive Young Stellar Object G036.70+00.09
Ichikawa, Kohei; Uchiyama, Mizuho; Yonekura, Yoshinori +2 more
We present the discovery of the simultaneous flux variation of a massive young stellar object (MYSO) G036.70+00.09 (G036.70) both in the maser emission and mid-infrared (MIR; λ = 3-5 µm) bands. Using the ALLWISE and NEOWISE archival databases that cover a long time span of approximately 10 yr with a cadence of 6 months, we confirm that G036.…