Search Publications
The Hercules cluster in X-rays with XMM-Newton and Chandra
Singh, Kulinder Pal; Tiwari, Juhi
We present a detailed X-ray study of the central subcluster of the nearby ( $z\, \sim$ 0.0368) Hercules cluster (Abell 2151) identified as A2151C that shows a bimodal structure. A bright clump of hot gas with X-ray emission extending to radius $r\, \sim$ 304 kpc and $L_X = 3.03_{-0.04}^{+0.02}\times 10^{43}$ erg s-1 in the 0.4-7.0 keV e…
An intermediate-velocity H I cloud falling to the galactic disk; Possible evidence for low-metallicity H I gas originating outside the galactic disk
Tachihara, Kengo; Sasaki, Manami; Fukui, Yasuo +6 more
We found that an intermediate-velocity cloud (IVC), IVC 86-36, in H I 21 cm emission shows a head-tail distribution toward the Galactic plane with marked parallel filamentary streamers, which is extended over 40° in the sky. The distance of IVC 86-36 is constrained to be less than ∼3 kpc from absorption of a background star as determined from opti…
Comparing the spatial and kinematic distribution of gas and young stars around the shell-like structure in the CMa OB1 association
Lefloch, B.; Montmerle, T.; Gregorio-Hetem, J. +4 more
Context. The relationship between young stellar clusters and their respective parental molecular clouds remains an open issue. Recent inquiries consider the similarities between substructures of clouds and clusters and whether they are a coincidence or, rather, an indication of a physical relationship. To address these issues, we studied the CMa O…
Galactic cosmic ray modulation at Mars and beyond measured with EDACs on Mars Express and Rosetta
Johnstone, A.; Lester, M.; Wimmer-Schweingruber, R. F. +5 more
Galactic cosmic rays (GCRs) are an intrinsic part of the heliospheric radiation environment and an inevitable challenge to long-term space exploration. Here we show solar-cycle-induced GCR modulation at Mars in the period 2005-2020, along with GCR radial gradients, by comparing Mars Express and Rosetta engineering parameters to sunspot number time…
The Galactic Chemical Evolution of Chlorine
Pilachowski, C. A.; Maas, Z. G.
We measured 35Cl abundances in 52 M giants with metallicities in the range -0.5 < [Fe/H] < 0.12. Abundances and atmospheric parameters were derived using infrared spectra from CSHELL on the NASA Infrared Telescope Facility and from optical echelle spectra. We measured Cl abundances by fitting a H35Cl molecular feature a…
Heavy Positive Ion Groups in Titan's Ionosphere from Cassini Plasma Spectrometer IBS Observations
Coates, Andrew J.; Lavvas, Panayotis; Waite, J. Hunter +4 more
Titan's ionosphere contains a plethora of hydrocarbons and nitrile cations and anions as measured by the Ion Neutral Mass Spectrometer and Cassini Plasma Spectrometer (CAPS) on board the Cassini spacecraft. Data from the CAPS Ion Beam Spectrometer (IBS) sensor have been examined for five close encounters of Titan during 2009. The high relative vel…
RGB photometric calibration of 15 million Gaia stars
Cardiel, Nicolás; Zamorano, Jaime; Masana, Eduard +6 more
Although a catalogue of synthetic RGB magnitudes, providing photometric data for a sample of 1346 bright stars, has been recently published, its usefulness is still limited due to the small number of reference stars available, considering that they are distributed throughout the whole celestial sphere, and the fact that they are restricted to John…
A Closer Look at Two of the Most Luminous Quasars in the Universe
Fan, Xiaohui; Huang, Yun-Hsin; Walter, Fabian +7 more
Ultraluminous quasars (M1450 ≤ -29) provide us with a rare view into the nature of the most massive and most rapidly accreting supermassive black holes (SMBHs). Following the discovery of two of these extreme sources, J0341+1720 (M1450 = -29.56, z = 3.71) and J2125-1719 (M1450 = -29.39, z = 3.90), in the Extremely …
Radioactive isotopes in the interstellar medium
Diehl, Roland
Radioactive components of the interstellar medium provide an entirely-different and new aspect to the studies of the interstellar medium. Injected from sources of nucleosynthesis, unstable nuclei decay along their trajectories. Measurements can occur through characteristic gamma rays that are emitted with the decay, or in cosmic material samples t…
Are Compton-thin AGNs Globally Compton Thin?
Yukita, M.; Ptak, A.; LaMassa, S. +2 more
We select eight nearby active galactic nuclei (AGNs) which, based on previous work, appear to be Compton-thin in the line of sight. We model with MYTORUS their broadband X-ray spectra from 20 individual observations with Suzaku, accounting self-consistently for Fe Kα line emission, as well as direct and scattered continuum from matter with finite …