Search Publications
The Discovery of Two LISA Sources within 0.5 kpc
Kilic, Mukremin; Bédard, A.; Kosakowski, Alekzander +1 more
We report the discovery of the brightest detached binary white dwarfs with periods less than an hour, which provide two new gravitational-wave verification binaries for the Laser Interferometer Space Antenna (LISA). The first one, SMSS J033816.16-813929.9 (hereafter J0338), is a 30.6 minute orbital period, g = 17.2 mag detached double white dwarf …
The MAVERIC Survey: Variable Jet-accretion Coupling in Luminous Accreting Neutron Stars in Galactic Globular Clusters
Strader, Jay; Bahramian, Arash; Maccarone, Thomas J. +9 more
Accreting neutron stars in low-mass X-ray binaries show outflows-and sometimes jets-in the general manner of accreting black holes. However, the quantitative link between the accretion flow (traced by X-rays) and outflows and/or jets (traced by radio emission) is much less well understood for neutron stars than for black holes, other than the gene…
The 2175 Å Dust Feature in Star-forming Galaxies at 1.3 ≤ z ≤ 1.8: The Dependence on Stellar Mass and Specific Star Formation Rate
Kartaltepe, Jeyhan S.; Daddi, Emanuele; Kashino, Daichi +10 more
We present direct spectroscopic measurements of the broad 2175 Å absorption feature in 505 star-forming main-sequence galaxies at 1.3 ≤ z ≤ 1.8 using individual and stacked spectra from the zCOSMOS-deep survey. Significant 2175 Å excess absorption features of moderate strength are measured, especially in the composite spectra. The excess absorptio…
ALMA Super-resolution Imaging of T Tau: r = 12 au Gap in the Compact Dust Disk around T Tau N
Tamura, Motohide; Yamaguchi, Masayuki; Nomura, Hideko +5 more
Based on Atacama Large Millimeter/submillimeter Array (ALMA) observations, compact protoplanetary disks with dust radii of r ≲ 20-40 au were found to be dominant in nearby low-mass star formation regions. However, their substructures have not been investigated because of the limited spatial resolution achieved so far. We apply a newly developed su…
Improved Measurements of the Sun's Meridional Flow and Torsional Oscillation from Correlation Tracking on MDI and HMI Magnetograms
Mahajan, Sushant S.; Hathaway, David H.; Muñoz-Jaramillo, Andrés +1 more
The Sun's axisymmetric flows, differential rotation, and meridional flow govern the dynamics of the solar magnetic cycle, and a variety of methods are used to measure these flows, each with its own strengths and weaknesses. Flow measurements based on cross-correlating images of the surface magnetic field have been made since the 1970s that require…
Tully-Fisher Distances and Dynamical Mass Constraints for 24 Host Galaxies of Reverberation-mapped AGNs
Crenshaw, D. M.; Bentz, Misty C.; Courtois, Hélène M. +6 more
We present Tully-Fisher distances for 24 active galactic nucleus (AGN) host galaxies with black hole mass (MBH) measurements from reverberation mapping, as well as the first calibration of the V-band Tully-Fisher relation. Combining our measurements of H I 21 cm emission with Hubble Space Telescope and ground-based optical and near-infr…
Multiple Stellar Populations at Less-evolved Stages: Detection of Chemical Variations among Main-sequence Dwarfs in NGC 1978
Milone, Antonino P.; Hong, Jongsuk; de Grijs, Richard +4 more
Multiple stellar populations (MPs) with different chemical compositions are not exclusive features of old globular clusters (older than 10 Gyr). Indeed, recent studies reveal that younger clusters (∼2-6 Gyr-old) in the Magellanic Clouds also exhibit star-to-star chemical variations among evolved stars. However, whether MPs are present among less-e…
Particle Reacceleration by Turbulence and Radio Constraints on Multimessenger High-energy Emission from the Coma Cluster
Murase, Kohta; Nishiwaki, Kosuke; Asano, Katsuaki
Galaxy clusters are considered to be gigantic reservoirs of cosmic rays (CRs). Some of the clusters are found with extended radio emission, which provides evidence for the existence of magnetic fields and CR electrons in the intra-cluster medium. The mechanism of radio halo (RH) emission is still under debate, and it has been believed that turbule…
Internal Structure of the 2019 April 2 CME
Vourlidas, Angelos; Wood, Brian E.; Braga, Carlos R.
We present the first analysis of internal coronal mass ejection (CME) structure observed very close to the Sun by the Wide-field Imager for Solar PRobe (WISPR) instrument on board the Parker Solar Probe (PSP). The transient studied here is a CME observed during PSP's second perihelion passage on 2019 April 2, when PSP was only 40 R ⊙ fr…
Detection of Al II in the Ultraviolet Spectra of Metal-poor Stars: An Empirical LTE Test of NLTE Aluminum Abundance Calculations
Roederer, Ian U.; Lawler, James E.
We report the detection of an Al II line at 2669.155 Å in 11 metal-poor stars, using ultraviolet spectra obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. We derive Al abundances from this line using a standard abundance analysis, assuming local thermodynamic equilibrium (LTE). The mean [Al/Fe] ratio is -0…