Search Publications
Accurate Ground-based Astrometry of Naked-eye Stars: The United States Naval Observatory Bright-star Astrometric Database
Harris, Hugh C.; Munn, Jeffrey A.; Subasavage, John P. +1 more
We present the United States Naval Observatory (USNO) Bright-star Astrometric Database (UBAD), a current-epoch high-accuracy astrometric catalog. The catalog consists of 364 bright northern hemisphere stars, including all but five such stars with either V < 3.5 or with I < 3.2 and V < 6, as well as a large fraction of slightly fainter sta…
Evidence for a Dense, Inhomogeneous Circumstellar Medium in the Type Ia SNR 0519-69.0
Petre, Robert; Reynolds, Stephen P.; Ghavamian, Parviz +3 more
We perform an expansion study of the Balmer-dominated outer shock of the SNR 0519-69.0 in the LMC by using a combination of new Hubble Space Telescope (HST) WFC3 imagery obtained in 2020 and archival ACS images from 2010 and 2011. Thanks to the very long time baseline, our proper motion measurements are of unprecedented accuracy. We find a wide ra…
HCN and HCO+ in Planetary Nebulae: The Next Level
Ziurys, L. M.; Schmidt, D. R.; Gold, K. R. +2 more
Observations of HCN and HCO+ have been carried out toward 13 planetary nebulae (PNe) using the facilities of the Arizona Radio Observatory (ARO). These nebulae represent a wide range of morphologies and ages (~2000-28,000 yr). For both molecules, the J = 1 → 0 transitions at 88-89 GHz and the J = 3 → 2 lines at 265-267 GHz were measured…
Orbital solution and dynamical masses for the nearby binary system GJ 67 AB
Torres, Guillermo
We report spectroscopic observations of the nearby, 19.5-yr binary system GJ 67AB spanning more than 35 yr. We carry out a global orbital solution combining our radial-velocity measurements with others from the literature going back more than a century, and with all other available astrometric observations. The latter include measurements of the r…
Regional Geology of the Hypanis Valles System, Mars
Bell, James F.; Dobrea, Eldar Noe; Adler, Jacob B. +2 more
We present a geomorphic map of the Hypanis Valles watershed and a geomorphic map of the Hypanis deposit region at its terminus. We mapped these two regions at different scales: 1:2,000,000 for the catchment map (−5° to 10°N and 300°-315°E) and 1:500,000 for the Hypanis deposit map (10°-13.0°N and 313°-316.5°E). Our mapping provides new morphologic…
Optical spectroscopy of the Be/black hole binary MWC 656 - interaction of a black hole with a circumstellar disc
Bode, Michael F.; Stefanov, Stefan Y.; Marchev, Dragomir +7 more
We present new spectroscopic observations of the Be/black hole binary MWC 656 obtained during the period 2015-2021. We measure the equivalent width of Hα (EWα), Hβ (EWβ), and the distance between the peaks of Hα (ΔVα), Hβ (ΔVβ), and FeII (ΔVFeII) lines. Combining new and old data, we find that…
Pulse Timing Discovery of a Three-day Companion to the Hot Subdwarf BPM 36430
Hermes, J. J.; Barlow, Brad N.; Schaffenroth, Veronika +2 more
Hot subdwarf B stars are core-helium-burning objects that have undergone envelope stripping, likely by a binary companion. Using high-speed photometry from the Transiting Exoplanet Survey Satellite, we have discovered the hot subdwarf BPM 36430 is a hybrid sdBVrs pulsator exhibiting several low-amplitude g-modes and a strong p-mode puls…
Further Studies of the Association of Planetary Nebula BMP J16135406 with Galactic Open Cluster NGC 6067
Parker, Quentin A.; Sabin, Laurence; Zijlstra, Albert A. +3 more
Planetary Nebulae (PNe) that are physical members of Galactic open clusters are powerful probes that allow precise determination of their distance and crucially their initial mass on the main sequence. Here, we revisit the physical association of the PN BMP J1613–5406 with the open cluster NGC 6067 and present our preliminary results based on our …
Mass assembly history of dark matter haloes in the light of H0 tension
Kameli, Hamed; Baghram, Shant
The Hubble tension may introduce a new course of action to revise the standard Lambda cold dark matter (ΛCDM) model to unravel dark energy and dark matter physics. The Hubble parameter can be reconstructed by late-time observations of the background evolution model independently. We relate the reconstructed Hubble parameter to the structure format…
Understanding the physical state of hot plasma formed through stellar wind collision in WR140 using high-resolution X-ray spectroscopy
Hamaguchi, Kenji; Miyamoto, Asca; Sugawara, Yasuharu +5 more
We analyse a series of XMM-Newton RGS data of the binary Wolf-Rayet star WR140 that encompasses one entire orbit. We find that the RGS detects X-rays from optically thin thermal plasma only during orbital phases when the companion O star is on the near side of the WR star. Although such X-rays are believed to be emitted from the shock cone formed …