Search Publications
Characterizing the low-altitude magnetic belt at Venus: Complementary observations from the Pioneer Venus Orbiter and Venus Express
Luhmann, J. G.; Russell, C. T.; Wei, H. Y. +4 more
Using Venus Express, Zhang et al. (2012b) identified strong magnetic field enhancements at low altitudes over the north polar region of Venus as giant flux ropes. Strong fields at low altitudes were also observed during the Pioneer Venus Orbiter mission, but at low latitudes near the subsolar and midnight regions. We examine the possibility that t…
A multiwavelength study of the M dwarf binary YY Geminorum
Bromage, G. E.; Doyle, J. G.; Foing, B. +8 more
We review the results of the 1988 multiwavelength campaign on the late-type eclipsing binary YY Geminorum. Observations include: broad-band optical and near-infrared photometry, simultaneous optical and ultraviolet (IUE) spectroscopy, X-ray (Ginga) and radio (VLA) data. From models fitted to the optical light curves, fundamental physical parameter…
Discovery of Nine Extended Ionized Gas Clouds in a z = 0.4 Cluster
Gu, Liyi; Koyama, Yusei; Kodama, Tadayuki +4 more
From deep Hα imaging data of Suprime-Cam/Subaru, we discovered nine extended ionized gas clouds (EIG) around galaxies in the Abell 851 cluster (A851) at z = 0.4. We surveyed a 30 × 25 arcmin region, and the EIGs were found only near the cluster center (\lt 2.3 arcmin ∼ 750 kpc). The parent galaxies of the EIGs are star-forming or post-starburst ga…
Doppler disc tomography applied to low-mass AGN spin
Middleton, Matthew J.; Ingram, Adam R.
Doppler tomography can provide a powerful means of determining black hole spin when our view to the central regions are revealed and obscured by optically thick orbiting material, and can provide an independent estimate that does not suffer as many degeneracies as traditional methods. For low-mass active galactic nuclei (AGN), time-dependent obscu…
The infrared massive stellar content of M 83
Whitmore, B. C.; Bonanos, A. Z.; Prieto, J. L. +2 more
Aims: We present an analysis of archival Spitzer images and new ground-based and Hubble Space Telescope (HST) near-infrared (IR) and optical images of the field of M 83 with the goal of identifying rare, dusty, evolved massive stars.
Methods: We present point source catalogs consisting of 3778 objects from Spitzer Infrared Array Camera (…
Optical Spectroscopy of Supernova Remnants in M81 and M82
Park, Byeong-Gon; Hwang, Narae; Koo, Bon-Chul +7 more
We present spectroscopy of 28 supernova remnant (SNR) candidates as well as one H ii region in M81 and two SNR candidates in M82. Twenty-six of the M81 candidates turn out to be genuine SNRs, and two in M82 may be shocked condensations in the galactic outflow or SNRs. The distribution of [N ii]/Hα ratios of M81 SNRs is bimodal. M81 SNRs are divide…
Ages of Star Clusters in the Tidal Tails of Merging Galaxies
Whitmore, B. C.; Chandar, R.; Mulia, A. J.
We study the stellar content in the tidal tails of three nearby merging galaxies, NGC 520, NGC 2623, and NGC 3256, using BVI imaging taken with the Advanced Camera for Surveys on board the Hubble Space Telescope. The tidal tails in all three systems contain compact and fairly massive young star clusters, embedded in a sea of diffuse, unresolved st…
X-ray lines and self-interacting dark matter
Mambrini, Yann; Toma, Takashi
We study the correlation between a monochromatic signal from annihilating dark matter and its self-interacting cross section. We apply our argument to a complex scalar dark sector, where the pseudo-scalar plays the role of a warm dark matter candidate while the scalar mediates its interaction with the Standard Model. We combine the recent observat…
Modeling the interaction between convection and nonthermal ion outflows
Wiltberger, M.; Lotko, W.; Varney, R. H.
Initial demonstrations of an ionosphere/polar wind model including a phenomenological treatment of transverse heating by wave particle interactions (WPIs) are presented. Tests with fixed WPI parameters in a designated heating region on the dayside with time-varying convection show that the parameters of the resulting nonthermal ion outflow are str…
Quasi-periodic Oscillation of a Coronal Bright Point
Tian, Hui; Banerjee, Dipankar; Samanta, Tanmoy
Coronal bright points (BPs) are small-scale luminous features seen in the solar corona. Quasi-periodic brightenings are frequently observed in the BPs and are generally linked with underlying magnetic flux changes. We study the dynamics of a BP seen in the coronal hole using the Atmospheric Imaging Assembly images, the Helioseismic and Magnetic Im…