Search Publications
On Measuring Divergence for Magnetic Field Modeling
Leka, K. D.; Barnes, G.; Wheatland, M. S. +2 more
A physical magnetic field has a divergence of zero. Numerical error in constructing a model field and computing the divergence, however, introduces a finite divergence into these calculations. A popular metric for measuring divergence is the average fractional flux $\left\langle | {f}_{i}| \right\rangle $ . We show that $\left\langle | {f}_{i}| \r…
Ultraviolet Line Identifications and Spectral Formation Near Max Light in Type Ia Supernova 2011fe
Baron, E.; Wang, Lifan; Branch, David +4 more
We present ultraviolet line identifications of near maximum-light Hubble Space Telescope observations of SN 2011fe using synthetic spectra generated from both SYNOW and PHOENIX. We find the spectrum to be dominated by blends of iron group elements Fe, Co, and Ni (as expected due to heavy line blanketing by these elements in the UV) and for the fir…
Multiwavelength Photometry and Progenitor Analysis of the Nova V906 Car
Law, Nicholas M.; Blagorodnova, Nadejda; Kupfer, Thomas +12 more
We present optical and infrared photometry of the classical nova V906 Car, also known as Nova Car 2018 and ASASSN-18fv, which was discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) on 2018 March 16.32 UT (MJD 58193.0). The nova reached its maximum on MJD 58222.56 at Vmax = 5.84 ± 0.09 mag, and had decline times of ${t}_…
HST Survey of the Orion Nebula Cluster in the H2O 1.4 µm Absorption Band. III. The Population of Substellar Binary Companions
Gennaro, Mario; Pueyo, Laurent; Ubeda, Leonardo +4 more
We present new results concerning the substellar binary population in the Orion Nebula Cluster (ONC). Using the Karhunen-Loève Image Projection algorithm, we have reprocessed images taken with the IR channel of the Wide Field Camera 3 mounted on the Hubble Space Telescope to unveil faint, close companions in the wings of the stellar point-spread f…
NuSTAR Non-detection of a Faint Active Galactic Nucleus in an Ultraluminous Infrared Galaxy with Kpc-scale Fast Wind
Kawamuro, Taiki; Toba, Yoshiki; Noda, Hirofumi +4 more
Large-scale outflows are generally considered to be possible evidence that active galactic nuclei (AGNs) can severely affect their host galaxies. Recently, an ultraluminous infrared galaxy (ULIRG) at z = 0.49, AKARI J0916248+073034, was found to have a galaxy-scale [O III] λ5007 outflow with one of the highest energy-ejection rates at z < 1.6. …
Discovery of a Rare Late-type, Low-mass Wolf-Rayet Star in the LMC
Prochaska, J. Xavier; Morrell, Nidia; Bond, Howard E. +4 more
We report the serendipitous discovery of an object, UVQS J060819.93-715737.4, with a spectrum dominated by extremely intense, narrow C II emission lines. The spectrum is similar to those of the very rare, late-type [WC11] low-mass Wolf-Rayet stars. Despite the recognition of these stars as a distinct class decades ago, there remains barely a handf…
Sequential Lid Removal in a Triple-decker Chain of CME-producing Solar Eruptions
Joshi, Bhuwan; Joshi, Navin Chandra; Moore, Ronald L. +1 more
We investigate the onsets of three consecutive coronal mass ejection (CME) eruptions in 12 hr from a large bipolar active region (AR) observed by the Solar Dynamics Observatory (SDO), the Solar Terrestrial Relations Observatory (STEREO), the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and the Geostationary Operational Environmen…
The Timing Behavior of the Central Compact Object Pulsar 1E 1207.4-5209
Gotthelf, E. V.; Halpern, J. P.
We present 20 yr of timing observations for 1E 1207.4-5209, the central compact object in supernova remnant PKS 1209-51/52, to follow up on our detection of an unexpected timing glitch in its spin-down. Using new XMM-Newton and NICER observations of 1E 1207.4-5209, we now find that the phase ephemeris can be well modeled by either two small glitch…
Reflection Features in the X-Ray Spectrum of Fairall 9 and Implications for Tests of General Relativity
Abdikamalov, Askar B.; Ayzenberg, Dimitry; Bambi, Cosimo +2 more
X-ray reflection spectroscopy is potentially a powerful tool to probe the spacetime geometry around astrophysical black holes and test general relativity in the strong field regime. However, precision tests of general relativity are only possible if we employ the correct astrophysical model and if we can limit the systematic uncertainties. It is t…
PHAT XX. AGB Stars and Other Cool Giants in M31 Star Clusters
Dolphin, Andrew E.; Skillman, Evan D.; Williams, Benjamin F. +20 more
The presence of asymptotic giant branch (AGB) stars in clusters provides key constraints for stellar models, as has been demonstrated with historical data from the Magellanic Clouds. In this work, we look for candidate AGB stars in M31 star clusters from the Panchromatic Hubble Andromeda Treasury survey. Our photometric criteria selects stars brig…