Search Publications
Study of Complex Absorption and Reflection in a Unique Intermediate Polar Paloma
Dutta, Anirban; Rana, Vikram
We present the broadband (0.3-40.0 keV) X-ray analysis of a unique intermediate polar Paloma using simultaneous data from XMM-Newton and NuSTAR observatories. The X-ray power spectra show strong modulations over orbital period compared to spin period. The orbit-folded light curves show a single broad hump-like structure with strong dips for soft t…
Using Single-view Observations of Cometary Plasma Tails to Infer Solar Wind Speed
Wang, Yuming; Li, Xiaolei; Cheng, Long
A comet plasma tail is a product of the interaction between the solar wind and the comet's coma, and has long been studied as a natural probe of the solar wind condition. We previously developed a method to derive the solar wind speed from dual-view observations of comet plasma tails. Here we improve the method to use single-view observations by a…
Study of the Mass-loss Rate from the Sun
Gopalswamy, Nat; Yashiro, Seiji; Michalek, Grzegorz
We investigate the temporal evolution of the yearly total mass-loss rate (YTMLR) from the Sun through coronal mass ejections (CMEs) over solar cycles 23 and 24. The mass determination of CMEs can be subject to significant uncertainty. To minimize this problem, we have used extensive statistical analysis. For this purpose, we employed data included…
Ultraviolet Observations of Comet 96/P Machholz at Perihelion
Raymond, J. C.; Bemporad, A.; Giordano, S. +2 more
Ultraviolet spectra of Comet 96/P Machholz were obtained during its 2002 perihelion with the UltraViolet Coronagraph Spectrometer instrument on board the SOHO satellite. Emission from H I, C II, C III, and O I is detected near the nucleus. The outgassing rate is in line with the value extrapolated from rates at larger distances from the Sun, and a…
The Quasar Luminosity Function at z 5 via Deep Learning and Bayesian Information Criterion
Im, Myungshin; Shin, Suhyun; Kim, Yongjung
Understanding the faint end of quasar luminosity function (LF) at a high redshift is important since the number density of faint quasars is a critical element in constraining ultraviolet (UV) photon budgets for ionizing the intergalactic medium (IGM) in the early universe. Here, we present quasar LF reaching M 1450 ~ -22.0 AB mag at z ~…
The Impact of Inelastic Collisions with Hydrogen on NLTE Copper Abundances in Metal-poor Stars
Shi, Jianrong; Wang, Xiaofeng; Xu, Xiaodong
We investigate the non-local thermodynamic equilibrium (non-LTE, hereafter NLTE) analysis for Cu I lines with the updated model atom that includes quantum-mechanical rate coefficients of Cu + H and Cu+ + H- inelastic collisions from the recent study of Belyaev et al. The influence of these data on NLTE abundance determination…
CAHA/PPAK Integral-field Spectroscopic Observations of M81. I. Circumnuclear Ionized Gas
Li, Zhiyuan; García-Benito, Rubén; Li, Zongnan +1 more
Galactic circumnuclear environments of nearby galaxies provide unique opportunities for our understanding of the coevolution between supermassive black holes and their host galaxies. Here, we present a detailed study of ionized gas in the central kiloparsec region of M81, which hosts the closest prototype low-luminosity active galactic nucleus, ba…
Gas Dynamics in the Star-forming Region G18.148-0.283: Is It a Manifestation of Two Colliding Molecular Clouds?
Dey, Jyotirmoy; Pandian, Jagadheep D.; Lal, Dharam Vir
We report the results obtained from a multiwavelength study of the H II region G18.148-0.283 using the upgraded Giant Metrewave Radio Telescope at 1350 MHz, along with other archival data. In addition to the radio continuum emission, we have detected the H169α and H170α radio recombination lines toward G18.148-0.283 using a correlator bandwidth of…
The Expansion of the X-Ray Nebula Around η Car
Corcoran, Michael F.; Russell, C. M. P.; Hamaguchi, K. +8 more
The massive colliding wind binary system η Car is embedded in an X-ray emitting region having a characteristic temperature of a few million degrees, associated with ejecta produced during the 1840s, and in earlier outbursts. We use CHANDRA X-ray imaging observations obtained over the past two decades to directly measure the expansion of the X-ray …
The Warm Gas in the Milky Way: The Kinematical Model of C IV and Its Connection to Si IV
Bregman, Joel N.; Qu, Zhijie; Lindley, Ryan
We compose a 265-sight-line Milky Way C IV line-shape sample using the Hubble Space Telescope/Cosmic Origins Spectrograph archive, which is complementary to the existing Si IV samples. C IV has a higher ionization potential (47-64 eV) than Si IV (33-45 eV), so it also traces warm gas, which is roughly cospatial with Si IV. The spatial density dist…