Search Publications
Positional Offsets between SiO Masers in Evolved Stars and their Cross-matched Counterparts
Morris, Mark R.; Rich, R. Michael; Sjouwerman, Loránt O. +4 more
Observations of dust-enshrouded evolved stars selected from infrared catalogs requiring high positional accuracy, like infrared spectroscopy or long baseline radio interferometric observations, often require preparational observational steps determining a position with an accuracy much better than 1″. Using phase-referencing observations with the …
On the Nature of the X-Ray Emission from the Ultraluminous X-Ray Source, M33 X-8: New Constraints from NuSTAR and XMM-Newton
Williams, Benjamin F.; Zezas, Andreas; Maccarone, Thomas J. +12 more
We present nearly simultaneous NuSTAR and XMM-Newton observations of the nearby (832 kpc) ultraluminous X-ray source (ULX) M33 X-8. M33 X-8 has a 0.3-10 keV luminosity of L X ≈ 1.4 × 1039 erg s-1, near the boundary of the “ultraluminous” classification, making it an important source for understanding the link betwe…
Statistical Study of ICMEs with Low Mean Carbon Charge State Plasmas Detected from 1998 to 2011
Li, Gang; Yan, Xiaoli; Yao, Shuo +2 more
We present a statistical study of 219 ICMEs measured by both ACE and WIND from 1998 to 2011. ICME plasmas are defined as possessing cold materials if the carbon average charge states are lower than those of the preceding solar wind by three standard deviations and the carbon ionic temperature is lower than 106.05 K. A total of 69 ICMEs …
A Diagnostic of Coronal Elemental Behavior during the Inverse FIP Effect in Solar Flares
Brooks, David H.
The solar corona shows a distinctive pattern of elemental abundances that is different from that of the photosphere. Low first ionization potential (FIP) elements are enhanced by factors of several. A similar effect is seen in the atmospheres of some solar-like stars, while late-type M stars show an inverse FIP effect. This inverse effect was rece…
A Likely Supermassive Black Hole Revealed by Its Einstein Radius in Hubble Frontier Fields Images
Broadhurst, Tom; Ohyama, Youichi; Ford, Holland +4 more
At cosmological distances, gravitational lensing can in principle provide direct mass measurements of supermassive black holes (SMBHs). Here, we directly estimate the mass of a SMBH in the brightest cluster galaxy (BCG) of MACS J1149.5+2223 at z = 0.54 using one of the multiply lensed images of a background spiral galaxy at z = 1.49 projected clos…
The UV Spectrum of the Ultracool Dwarf LSR J1835+3259 Observed with the Hubble Space Telescope
Saur, Joachim; Roth, Lorenz; Feldman, Paul D. +4 more
An interesting question about ultracool dwarfs recently raised in the literature is whether their emission is purely internally driven or partially powered by external processes similar to planetary aurora known from the solar system. In this work, we present Hubble Space Telescope observations of the energy fluxes of the M8.5 ultracool dwarf LSR …
Untwisting Jets Related to Magnetic Flux Cancellation
Wang, Yuming; Liu, Rui; Liu, Jiajia +1 more
The rotational motion of solar jets is believed to be a signature of the untwisting process resulting from magnetic reconnection, which takes place between twisted closed magnetic loops (i.e., magnetic flux ropes) and open magnetic field lines. The identification of the pre-existing flux rope, and the relationship between the twist contained in th…
Simultaneous VLBI Astrometry of H2O and SiO Masers toward the Semiregular Variable R Crateris
Kim, Dong-Jin; Rioja, María J.; Dodson, Richard +7 more
We obtained, for the first time, astrometrically registered maps of the 22.2 GHz H2O and 42.8, 43.1, and 86.2 GHz SiO maser emission toward the semiregular b-type variable (SRb) R Crateris, at three epochs (2015 May 21, and 2016 January 7 and 26) using the Korean Very-long-baseline Interferometry Network. The SiO masers show a ring-like…
Flux Relaxation after Two Outbursts of the Magnetar SGR 1627-41 and Possible Hard X-Ray Emission
An, Hongjun; Kaspi, Victoria M.; Cumming, Andrew
We report on the long-term flux relaxation of the magnetar SGR 1627-41 after its 2008 outburst, and evidence for hard X-ray excess measured with NuSTAR. We use new observations made with Chandra and XMM-Newton, and an archival NuSTAR observation, which add flux measurements at ∼2000 days into quiescence after the 2008 outburst. We find that the so…
Hard X-Ray View of HCG 16 (Arp 318)
Tanimoto, Atsushi; Ueda, Yoshihiro; Ricci, Claudio +1 more
We report the hard X-ray (3-50 keV) view of the compact group HCG 16 (Arp 318) observed with the Nuclear Spectroscopic Telescope Array (NuSTAR). NGC 838 and NGC 839 are undetected at energies above 8 keV, showing no evidence of heavily obscured active galactic nuclei (AGNs). This confirms that these are starburst-dominant galaxies as previously su…