Search Publications
High-latitude Conic Current Sheets in the Solar Wind
Tokumaru, Munetoshi; Fujiki, Ken'ichi; Malova, Helmi V. +7 more
We provide observational evidence for the existence of large-scale cylindrical (or conic-like) current sheets (CCSs) at high heliolatitudes. Long-lived CCSs were detected by Ulysses during its passages over the South Solar Pole in 1994 and 2007. The characteristic scale of these tornado-like structures is several times less than a typical width of…
Swift, XMM-Newton, and NuSTAR Observations of PSR J2032+4127/MT91 213
Takata, J.; Kong, A. K. H.; Hui, C. Y. +3 more
We report our recent Swift, NuSTAR, and XMM-Newton X-ray and Lijiang optical observations on PSR J2032+4127/MT91 213, the γ-ray binary candidate with a period of 45-50 years. The coming periastron of the system was predicted to be in 2017 November, around which high-energy flares from keV to TeV are expected. Recent studies with Chandra and Swift …
Morphology and the Color-mass Diagram as Clues to Galaxy Evolution at z&approx1
Schawinski, Kevin; Urry, C. Megan; Simmons, Brooke D. +4 more
We study the significance of mergers in the quenching of star formation in galaxies at z∼ 1 by examining their color-mass distributions for different morphology types. We perform two-dimensional light profile fits to GOODS iz images of ∼5000 galaxies and X-ray selected active galactic nucleus (AGN) hosts in the CANDELS/GOODS-north and south fields…
Observational Evidence Linking Interstellar UV Absorption to PAH Molecules
Behar, Ehud; Brosch, Noah; Tielens, Alexander G. G. M. +2 more
The 2175 Å UV extinction feature was discovered in the mid-1960s, yet its physical origin remains poorly understood. One suggestion is absorption by polycyclic aromatic hydrocarbon (PAH) molecules, which is supported by theoretical molecular structure computations and by laboratory experiments. PAHs are positively detected by their 3.3, 6.2, 7.7, …
Identification of Faint Chandra X-Ray Sources in the Core-collapsed Globular Cluster NGC 6752
Anderson, Jay; Heinke, Craig O.; Cool, Adrienne M. +2 more
We have searched for optical identifications for 39 Chandra X-ray sources that lie within the 1.‧9 half-mass radius of the nearby (d=4.0 {kpc}), core-collapsed globular cluster, NGC 6752, using deep Hubble Space Telescope ACS/WFC imaging in B 435, {R}625, and Hα. Photometry of these images allows us to classify candidate coun…
No Neon, but Jets in the Remarkable Recurrent Nova M31N 2008-12a?—Hubble Space Telescope Spectroscopy of the 2015 Eruption
Ness, J. -U.; Henze, M.; Shafter, A. W. +14 more
The 2008 discovery of an eruption of M31N 2008-12a began a journey on which the true nature of this remarkable recurrent nova continues to be revealed. M31N 2008-12a contains a white dwarf (WD) close to the Chandrasekhar limit, accreting at a high rate from its companion, and undergoes thermonuclear eruptions that are observed yearly and may even …
Discovery of Two Small High-velocity Compact Clouds in the Central 10 pc of Our Galaxy
Oka, Tomoharu; Iwata, Yuhei; Nomura, Mariko +2 more
We discovered two small high-velocity compact clouds (HVCCs) in the HCN J = 4-3 and J = 3-2 maps of the central 20 pc of our Galaxy. Both HVCCs have broad velocity widths ({{Δ }}V≳ 40 km s-1) and compact sizes (d∼ 1 {pc}), and originate from the dense molecular clouds in the position-velocity space. One of them has a faint counterpart i…
Detection of Very Low-frequency, Quasi-periodic Oscillations in the 2015 Outburst of V404 Cygni
Kouveliotou, C.; Gehrels, N.; van der Klis, M. +12 more
In 2015 June, the black hole X-ray binary (BHXRB) V404 Cygni went into outburst for the first time since 1989. Here, we present a comprehensive search for quasi-periodic oscillations (QPOs) of V404 Cygni during its recent outburst, utilizing data from six instruments on board five different X-ray missions: Swift/XRT, Fermi/GBM, Chandra/ACIS, INTEG…
The 1600 Å Emission Bump in Protoplanetary Disks: A Spectral Signature of H2O Dissociation
France, Kevin; Roueff, Evelyne; Abgrall, Hervé
The FUV continuum spectrum of many accreting pre-main sequence stars, Classical T Tauri Stars (CTTSs), does not continue smoothly from the well-studied Balmer continuum emission in the NUV, suggesting that additional processes contribute to the short-wavelength emission in these objects. The most notable spectral feature in the FUV continuum of so…
ALMA Multiple-transition Molecular Line Observations of the Ultraluminous Infrared Galaxy IRAS 20551-4250: Different HCN, HCO+, and HNC Excitation, and Implications for Infrared Radiative Pumping
Imanishi, Masatoshi; Izumi, Takuma; Nakanishi, Kouichiro
We present our ALMA multi-transition molecular line observational results for the ultraluminous infrared galaxy IRAS 20551-4250, which is known to contain a luminous buried active galactic nucleus and shows detectable vibrationally excited (v 2 = 1f) HCN and HNC emission lines. The rotational J = 1-0, 4-3, and 8-7 of HCN, {HCO}}+