Search Publications
New Fe I Level Energies and Line Identifications from Stellar Spectra. III. Initial Results from UV, Optical, and Infrared Spectra
Peterson, Ruth C.; Kurucz, Robert L.
The spectrum of neutral iron is critical to astrophysics, yet furnace laboratory experiments cannot reach high-lying Fe I levels. Instead, Peterson & Kurucz and Peterson et al. adopted ultraviolet (UV) and optical spectra of warm stars to identify and assign energies for 124 Fe I levels with 1900 detectable Fe I lines, and to derive astrophysi…
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…
Stellar Populations in type Ia supernova host galaxies at intermediate-high redshift: Star formation and metallicity enrichment histories
Galbany, L.; Mollá, M.; Gomes, J. M. +5 more
We present a summary of our project that studies galaxies hosting type Ia supernova (SN Ia) at different redshifts. We present Gran Telescopio de Canarias (GTC) optical spectroscopy of six SN Ia host galaxies at redshift z ~ 0.4-0.5. They are joined to a set of SN Ia host galaxies at intermediate-high redshift, which include galaxies from surveys …
A window into magnetic reconnection: IRIS observations of the consequences of reconnection during solar flares
Reeves, Katharine K.
Magnetic reconnection is a dynamic process that occurs in solar flares in a tenuous and hot environment. High-cadence, high-spatial resolution spectroscopic observations with the Interface Region Imaging Spectrometer (IRIS) have provided a unique window into the reconnection process that occurs during solar flares. IRIS has observed many consequen…
Probing the parameters of the intergalactic medium using quasars
Morris, Simon L.; Fumagalli, Michele; Gatuzz, Efrain +1 more
We continue our series of papers on intergalactic medium (IGM) tracers using quasi-stellar objects (QSOs), having examined gamma-ray bursts (GRBs) and blazars in earlier studies. We have estimated the IGM properties of hydrogen column density ($\mathit {N}\small {\rm HXIGM}$), temperature, and metallicity using XMM-Newton QSO spectra over a large …
Effect of the solar wind on the nature of arbitrary amplitude ion-acoustic solitary waves in Venus' upper ionosphere
Fichtner, H.; Lazar, M.; El-Shafeay, N. A. +5 more
Observations suggest that at altitudes of 1000-2000 km the interaction between the solar wind and Venus' ionospheric plasma leads to ion-acoustic waves (IAWs) formation. For studying this hypothesis, a suitable hydrodynamic model relying on the observational data from Pioneer Venus Orbiter (PVO) and Venus Express (VEX) is developed. It consists of…
Morphological analyses of small and medium size landforms in Scandia Cavi and Olympia Undae, Northern circumpolar region of mars
Kereszturi, Akos; Martin, Patrick; Sánchez-Bayton, Marina +3 more
This article presents a systematic morphological analysis of the topographic landforms at Olympia Undae and Scandia Cavi in the northern circumpolar region of Mars. The study has been performed using images from Mars Express and Mars Reconnaissance Orbiter, as well as topographic profiles from Mars Global Surveyor of 200 small and medium-size geol…
Revisiting the Evidence for an Intermediate-mass Black Hole in the Center of NGC 6624 with Simulations
Wang, Li-Chun; Xie, Yi
The acceleration of LMXB 4U 1820-30 derived from its orbital-period derivative ${\dot{P}}_{{\rm{b}}}$ was supposed to be the evidence for an Intermediate-mass black hole (IMBH) in the Galactic globular cluster (GC) NGC 6624. However, we find that the anomalous ${\dot{P}}_{{\rm{b}}}$ is mainly due to the gravitational wave emission, rather than the…
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 nature of the X-ray sources constituting the 6.7 keV Galactic ridge emission
Schmitt, J. H. M. M.; Czesla, S.; Robrade, J. +2 more
We reanalyze the deep Chandra X-ray observations near the Galactic center and show that reliable identifications of X-ray sources can be obtained with the Gaia EDR3 data to investigate which types of stellar sources are responsible for the X-ray emission observed from the Galactic ridge (GRXE). In the central 3 arcmin region 318 X-ray sources are …