Search Publications
Galactic Rotation and the Oort Constants in the Solar Vicinity
Zhao, Gang; Li, Chengdong; Yang, Chengqun
Gaia DR2 data are used to calculate the Oort constants and derive the Galactic rotational properties in this work. We choose the solar vicinity stars with a “clean” sample within 500 pc. The Oort constants are then fitted through the relation between the proper motions as a function of Galactic longitude l. A maximum likelihood method is adopted t…
Spectral and Timing Analysis of the Accretion-powered Pulsar 4U 1626-67 Observed with Suzaku and NuSTAR
Enoto, Teruaki; Chakrabarty, Deepto; Terada, Yukikatsu +13 more
We present an analysis of the spectral shape and pulse profile of the accretion-powered pulsar 4U 1626-67 observed with Suzaku and Nuclear Spectroscopic Telescope Array (NuSTAR) during a spin-up state. The pulsar, which experienced a torque reversal to spin-up in 2008, has a spin period of ∼7.7 s. Comparing the phase-averaged spectra obtained with…
Distances to Galactic OB Stars: Photometry versus Parallax
Shull, J. Michael; Danforth, Charles W.
For application to surveys of interstellar matter and Galactic structure, we compute new spectrophotometric distances to 139 OB stars frequently used as background targets for UV spectroscopy. Many of these stars have updated spectral types and digital photometry with reddening corrections from the Galactic O-Star (GOS) spectroscopic survey. We co…
On the Origin of Solar Torsional Oscillations and Extended Solar Cycle
Kosovichev, A. G.; Pipin, V. V.
We present a nonlinear mean-field model of the solar interior dynamics and dynamo, which reproduces the observed cyclic variations of the global magnetic field of the Sun, as well as the differential rotation and meridional circulation. Using this model, we explain, for the first time, the extended 22 yr pattern of the solar torsional oscillations…
Detecting Thin Stellar Streams in External Galaxies: Resolved Stars and Integrated Light
Williams, Benjamin F.; Ibata, Rodrigo A.; Johnston, Kathryn V. +3 more
The morphology of thin stellar streams can be used to test the nature of dark matter. It is therefore crucial to extend searches for globular cluster (GC) streams to other galaxies than the Milky Way. In this paper, we investigate the current and future prospects of detecting GC streams in external galaxies in resolved stars (e.g., with Wide Field…
Stellar Mass Growth of Brightest Cluster Galaxy Progenitors in COSMOS Since z ∼ 3
Casey, Caitlin M.; Kartaltepe, Jeyhan S.; Le Fèvre, Olivier +5 more
We examine the role of environment on the in situ star formation (SF) hosted by the progenitors of the most massive galaxies in the present-day universe, the brightest cluster galaxies (BCGs), from z ∼ 3 to present in the COSMOS field. Progenitors are selected from the COSMOS field using a stellar mass cut motivated by the evolving cumulative como…
An Enormous Molecular Gas Flow in the RX J0821+0752 Galaxy Cluster
Fabian, A. C.; Combes, F.; McDonald, M. +6 more
We present recent Chandra X-ray observations of the RX J0821.0+0752 galaxy cluster, in addition to ALMA observations of the CO(1-0) and CO(3-2) line emission tracing the molecular gas in its central galaxy. All of the CO line emission, originating from a {10}10 {M}⊙ molecular gas reservoir, is located several kiloparsecs awa…
The Planet Formation Potential around a 45 Myr Old Accreting M Dwarf
Hughes, A. Meredith; Murphy, Simon J.; Mamajek, Eric E. +1 more
Debris disk detections around M dwarfs are rare, and so far no gas emission has been detected from an M dwarf debris disk. This makes the 45 Myr old M dwarf WISE J080822.18-644357.3 a bit of a curiosity; it has a strong infrared excess at an age beyond the lifetime of a typical planet-forming disk, and also exhibits broad Hα emission consistent wi…
ALMA Observations of Atomic Carbon [C I] ( 3 P 1 → 3 P 0 ) and Low-J CO Lines in the Starburst Galaxy NGC 1808
Seta, Masumichi; Salak, Dragan; Nakai, Naomasa +1 more
We present [C I] ≤ft({}3{{P}}1\to {}3{{P}}0\right), 12CO, 13CO, and C18O (J=2\to 1) observations of the central region (radius 1 kpc) of the starburst galaxy NGC 1808 at 30-50 pc resolution conducted with the Atacama Large Millimeter/submillimeter Array. Radiative transfe…
The Precious Set of Radio-optical Reference Frame Objects in the Light of Gaia DR2 Data
Schmitt, Henrique R.; Makarov, Valeri V.; Berghea, Ciprian T. +2 more
We investigate a sample of 3413 International Celestial Reference Frame (ICRF3) extragalactic radio-loud sources with accurate positions determined by very long baseline interferometry in the S/X band, mostly active galactic nuclei and quasars, which are cross-matched with optical sources in the second Gaia data release (Gaia DR2). The main goal o…