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Star-forming Environments throughout the M101 Group
Mihos, J. Christopher; Harding, Paul; Watkins, Aaron E.
We present a multiwavelength study of star formation within the nearby M101 Group, including new deep Hα imaging of M101 and its two companions. We perform a statistical analysis of the Hα-to-FUV flux ratios in H II regions located in three different environments: M101's inner disk, M101's outer disk, and M101's lower-mass companion galaxy NGC 547…
Interplanetary Magnetic Flux Ropes as Agents Connecting Solar Eruptions and Geomagnetic Activities
Marubashi, K.; Cho, K. -S.; Ishibashi, H.
We investigate the solar wind structure for 11 cases that were selected for the campaign study promoted by the International Study of Earth-affecting Solar Transients (ISEST) MiniMax24 Working Group 4. We can identify clear flux rope signatures in nine cases. The geometries of the nine interplanetary magnetic flux ropes (IFRs) are examined with a …
A moderately precise dynamical age for the Homunculus of Eta Carinae based on 13 years of HST imaging
Smith, Nathan
The Hubble Space Telescope archive contains a large collection of images of η Carinae, and this paper analyses those most suitable for measuring its expanding Homunculus Nebula. Multiple intensity tracings through the Homunculus reveal the fractional increase in the overall size of the nebula; this avoids registration uncertainty, mitigates bright…
Understanding the nature of the intriguing source X Persei: a deep look with a Suzaku observation
Maitra, Chandreyee; Paul, Biswajit; Pradhan, Pragati +1 more
We present detailed broad-band timing and spectral analysis of the persistent, low luminosity and slowly spinning pulsar X Persei using a deep Suzaku observation of the source. The spectrum is unusually hard with a cyclotron resonance scattering feature (CRSF), the presence of which has been debated. By comparing the spectral models relevant for a…
IMF dependence of energetic oxygen and hydrogen ion distributions in the near-Earth magnetosphere
Daly, P. W.; Kronberg, E. A.; Nykyri, K. +5 more
Energetic ion distributions in the near-Earth plasma sheet can provide important information for understanding the entry of ions into the magnetosphere and their transportation, acceleration, and losses in the near-Earth region. In this study, 11 years of energetic proton and oxygen observations (> 274 keV) from Cluster/Research with Adaptive P…
Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background
Cai, Rong-Gen; Guo, Zong-Kuan; Dai, Wei-Ming +1 more
We investigate constraints on Lorentz invariance violation in the neutrino sector from a joint analysis of big bang nucleosynthesis and the cosmic microwave background. The effect of Lorentz invariance violation during the epoch of big bang nucleosynthesis changes the predicted helium-4 abundance, which influences the power spectrum of the cosmic …
Nearby Young, Active, Late-type Dwarfs in Gaia's First Data Release
Zuckerman, B.; Kastner, Joel H.; Rodriguez, David +3 more
The Galex Nearby Young Star Survey (GALNYSS) has yielded a sample of ∼2000 UV-selected objects that are candidate nearby (D≲ 150 {pc}), young (age ∼ 10-100 Myr), late-type stars. Here, we evaluate the distances and ages of the subsample of (19) GALNYSS stars with Gaia Data Release 1 (DR1) parallax distances D≤slant 120 {pc}. The overall youth of t…
Siriusly, a newly identified intermediate-age Milky Way stellar cluster: a spectroscopic study of Gaia 1
Bernard, E. J.; Tolstoy, E.; Ferguson, A. M. N. +6 more
We confirm the reality of the recently discovered Milky Way stellar cluster Gaia 1 using spectra acquired with the HERMES and AAOmega spectrographs of the Anglo-Australian Telescope. This cluster had been previously undiscovered due to its close angular proximity to Sirius, the brightest star in the sky at visual wavelengths. Our observations iden…
Emission Lines in the Near-infrared Spectra of the Infrared Quintuplet Stars in the Galactic Center
Najarro, F.; Geballe, T. R.; de la Fuente, D. +1 more
We report the detection of a number of emission lines in the 1.0-2.4 µm spectra of four of the five bright-infrared dust-embedded stars at the center of the Galactic center’s (GC) Quintuplet Cluster. Spectroscopy of the central stars of these objects is hampered not only by the large interstellar extinction that obscures all of the objects i…
Prominence Eruption Initiated by Helical Kink Instability of an Embedded Flux Rope
Gopalswamy, N.; Ravindra, B.; Vemareddy, P.
We study the triggering mechanism of a limb-prominence eruption and the associated coronal mass ejection (CME) near AR 12342 using Solar Dynamics Observatory and Large Angle and Spectrometric Coronagraph/Solar Heliospheric Observatory observations. The prominence is seen with an embedded flux thread (FT) at one end and bifurcates from the middle t…