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Variations of the Galactic Cosmic Rays in the Recent Solar Cycles
Zhao, Lingling; Fu, Shuai; Zhang, Xiaoping +1 more
In this paper, we study the Galactic cosmic-ray (GCR) variations over the solar cycles 23 and 24, with measurements from NASA's Advanced Composition Explorer/Cosmic Ray Isotope Spectrometer instrument and the ground-based neutron monitors (NMs). The results show that the maximum GCR intensities of heavy nuclei (5 ≤ Z ≤ 28, 50∼500 MeV nuc-1
Orbits of 152 globular clusters of the MilkyWay galaxy constructed from Gaia DR2
Bajkova, Anisa Talgatovna; Bobylev, Vadim Vadimovich
We present orbits and their properties for 152 globular clusters of the Milky Way galaxy obtained using average Gaia DR2 proper motions and other astrometric data from the list of Vasiliev. For orbital integration we have applied the axisymmetric model of the Galactic potential based on the Navarro-Frenk- White dark halo, and modified by Bajkova &…
The Milky Way's bar structural properties from gravitational waves
Korol, Valeriya; Rossi, Elena M.; D'Onghia, Elena +1 more
The Laser Interferometer Space Antenna (LISA) will enable Galactic gravitational wave (GW) astronomy by individually resolving >104 signals from double white dwarf (DWD) binaries throughout the Milky Way. Since GWs are unaffected by stellar crowding and dust extinction unlike optical observations of the Galactic plane, in this work, …
R-process-rich Stellar Streams in the Milky Way
Roederer, Ian U.; Frebel, Anna; Ji, Alexander P. +3 more
We present high-resolution Magellan/MIKE spectra of 22 bright (9 < V < 13.5) metal-poor stars (-3.18 < [Fe/H] < -1.37) in three different stellar streams, the Helmi debris stream, the Helmi trail stream, and the ω Centauri progenitor stream. We augment our Helmi debris sample with results for 10 stars by Roederer et al. for a total of …
Systematics and Consequences of Comet Nucleus Outgassing Torques
Jewitt, David
Anisotropic outgassing from comets exerts a torque sufficient to rapidly change the angular momentum of the nucleus, potentially leading to rotational instability. Here, we use empirical measures of spin changes in a sample of comets to characterize the torques, and to compare them with expectations from a simple model. Both the data and the model…
Rotation periods for cool stars in the open cluster NGC 3532. The transition from fast to slow rotation
Strassmeier, K. G.; Barnes, S. A.; James, D. J. +1 more
Context. A very rich cluster intermediate in age between the Pleiades (150 Myr) and the Hyades (600 Myr) is needed to probe the rotational evolution, especially the transition between fast and slow rotation that occurs between the two ages.
Aims: We study the rich 300 Myr-old open cluster NGC 3532 to probe this important transition and to pro…
ALMA Observations of the Sub-kpc Structure of the Host Galaxy of a z = 6.5 Lensed Quasar: A Rotationally Supported Hyper-Starburst System at the Epoch of Reionization
Fan, Xiaohui; Keeton, Charles R.; Walter, Fabian +11 more
We report Atacama Large Millimeter/Submillimeter Array (ALMA) observations of the dust continuum and [C II] emission of the host galaxy of J0439+1634, a gravitationally lensed quasar at z = 6.5. Gravitational lensing boosts the source-plane resolution to ~0"15 (~0.8 kpc). The lensing model derived from the ALMA data is consistent with the fiducial…
Data Mining Reconstruction of Magnetotail Reconnection and Implications for Its First-Principle Modeling
Sitnov, Mikhail; Stephens, Grant; Motoba, Tetsuo +1 more
Magnetic reconnection is a fundamental process providing topological changes of the magnetic field, reconfiguration of space plasmas and release of energy in key space weather phenomena, solar flares, coronal mass ejections and magnetospheric substorms. Its multiscale nature is difficult to study in observations because of their sparsity. Here we …
A Galactic survey of radio jets from massive protostars
Lumsden, S. L.; Purser, S. J. D.; Hoare, M. G. +1 more
In conjunction with a previous southern-hemisphere work, we present the largest radio survey of jets from massive protostars to date with high-resolution (~0.04 arcsec) Jansky Very Large Array observations towards two subsamples of massive star-forming regions of different evolutionary statuses: 48 infrared-bright, massive, young, stellar objects …
TESS Asteroseismology of α Mensae: Benchmark Ages for a G7 Dwarf and Its M Dwarf Companion
Butler, R. Paul; Chaplin, William J.; Stassun, Keivan G. +27 more
Asteroseismology of bright stars has become increasingly important as a method to determine the fundamental properties (in particular ages) of stars. The Kepler Space Telescope initiated a revolution by detecting oscillations in more than 500 main-sequence and subgiant stars. However, most Kepler stars are faint and therefore have limited constrai…