Search Publications
The Gamma-Ray Source AGL J2241+4454 as the Possible Counterpart of MWC 656
Verrecchia, F.; Sabatini, S.; Pittori, C. +5 more
AGILE discovered the transient source AGL J2241+4454 in 2010, which triggered the study of the associated field allowing for the discovery of the first Be/black hole binary system: MWC 656. This binary was suggested to be the counterpart of AGL J2241+4454, but this association is still not robust. In this work we explore the archival AGILE and Fer…
Departure of High-temperature Iron Lines from the Equilibrium State in Flaring Solar Plasmas
Keenan, F. P.; Kawate, T.; Jess, D. B.
The aim of this study is to clarify if the assumption of ionization equilibrium and a Maxwellian electron energy distribution is valid in flaring solar plasmas. We analyze the 2014 December 20 X1.8 flare, in which the Fe xxi 187 Å, Fe xxii 253 Å, Fe xxiii 263 Å, and Fe xxiv 255 Å emission lines were simultaneously observed by the EUV Imaging Spect…
Detection of HF Toward PKS 1830-211, Search for Interstellar H2F+, and Laboratory Study of H2F+ and H2Cl+ Dissociative Recombination
Muller, S.; Black, J. H.; Miyamoto, Y. +7 more
We report extragalactic observations of two fluorine-bearing species, hydrogen fluoride (HF) and fluoronium (H2F+), in the z = 0.89 absorber in front of the lensed blazar PKS 1830-211 with the Atacama Large Millimeter/submillimeter Array. HF was detected toward both southwest and northeast images of the blazar, with column de…
NuSTAR and XMM-Newton Observations of 1E1743.1-2843: Indications of a Neutron Star LMXB Nature of the Compact Object
Hailey, Charles J.; Mori, Kaya; Zhang, Shuo +13 more
We report on the results of NuSTAR and XMM-Newton observations of the persistent X-ray source 1E1743.1-2843, located in the Galactic Center region. The source was observed between 2012 September and October by NuSTAR and XMM-Newton, providing almost simultaneous observations in the hard and soft X-ray bands. The high X-ray luminosity points to the…
The VIRUS-P Exploration of Nearby Galaxies (VENGA): Radial Gas Inflow and Shock Excitation in NGC 1042
Blanc, Guillermo A.; Jogee, Shardha; Luo, Rongxin +3 more
NGC 1042 is a late-type bulgeless disk galaxy that hosts low-luminosity active galactic nuclei (AGNs) coincident with a massive nuclear star cluster. In this paper, we present the integral field spectroscopy studies of this galaxy, based on the data obtained with the Mitchell spectrograph on the 2.7 m Harlan J. Smith telescope. In the central 100-…
The Star Cluster Mass-Galactocentric Radius Relation: Implications for Cluster Formation
Fan, Zhou; de Grijs, Richard; Cameron, Ewan +1 more
Whether or not the initial star cluster mass function is established through a universal, galactocentric-distance-independent stochastic process, on the scales of individual galaxies, remains an unsolved problem. This debate has recently gained new impetus through the publication of a study that concluded that the maximum cluster mass in a given p…
X-ray Spectral and Optical Properties of a ULX in NGC 4258 (M106)
Balman, S.; Akyuz, A.; Aksaker, N. +3 more
We study the X-ray and optical properties of the ultraluminous X-ray source (ULX) X-6 in the nearby galaxy NGC 4258 (M106) based on the archival XMM-Newton, Chandra, Swift, and Hubble Space Telescope (HST) observations. The source has a peak luminosity of L X ∼ 2 × 1039 erg s-1 in the XMM-Newton observation of 2004…
Dynamical Estimate of Post-main-sequence Stellar Masses in 47 Tucanae
Heyl, Jeremy; Richer, Harvey; Kalirai, Jason +2 more
We use the effects of mass segregation on the radial distribution of different stellar populations in the core of 47 Tucanae to find estimates for the masses of stars at different post-main-sequence evolutionary stages. We take samples of main-sequence (MS) stars from the core of 47 Tucanae, at different magnitudes (I.e., different masses), and us…
Spatial Distribution and Kinematics of the Molecular Material Associated with eta Carinae
Menten, Karl M.; Zapata, Luis A.; Rodríguez, Luis F. +3 more
Single-dish submillimeter observations have recently revealed the existence of a substantial, chemically peculiar molecular gas component located in the innermost circumstellar environment of the very massive luminous blue variable star, η Carinae. Here, we present 5″-resolution interferometric observations of the 1\to 0 rotational transition of h…
Homologous Solar Events on 2011 January 27: Build-up and Propagation in a Complex Coronal Environment
Pick, M.; Démoulin, P.; Zucca, P. +2 more
In spite of the wealth of imaging observations at the extreme-ultraviolet (EUV), X-ray, and radio wavelengths, there are still relatively few cases where all of the imagery is available to study the full development of a coronal mass ejection (CME) event and its associated shock. The aim of this study is to contribute to the understanding of the r…