Search Publications
A Multiwavelength Study of the Formation of the AFGL 333-Ridge
Wang, Jun-Jie; Xu, Jin-Long; Xu, Ye +1 more
We presented a multiwavelength study of the AFGL 333-Ridge. The molecular line data reveals that the AFGL 333-Ridge has two independent velocity components at -50.5 and -48.0 km s-1. In the position-velocity diagram, the bridge feature connects with two parts that are spatially correlated but separated in velocity. This observational ev…
The Solar-cycle Variations of the Anisotropy of Taylor Scale and Correlation Scale in the Solar Wind Turbulence
Zhou, G.; He, H. -Q.
The field-aligned anisotropy of the solar wind turbulence, which is quantified by the ratio of the parallel to the perpendicular correlation (and Taylor) length scales, is determined by simultaneous two-point correlation measurements during the time period 2001-2017. Our results show that the correlation scale along the magnetic field is the large…
Radial Velocity Monitoring of the Young Star Hubble 4: Disentangling Star-spot Lifetimes from Orbital Motion
Anderson, Jay; Johns-Krull, Christopher M.; Prato, L. +1 more
We studied the weak-lined T Tauri star Hubble 4, a known long-period binary, and its star-spot phenomena. We used optical radial velocity (RV) data taken over a span of 14 yr (2004-2010, 2017-2019) at the McDonald Observatory 2.7 m Harlan J. Smith Telescope and single epoch imaging from the Hubble Space Telescope (HST)/Wide Field Camera 3 instrume…
A Rotating Azimuthally Distributed Auroral Current System on Saturn Revealed by the Cassini Spacecraft
Coates, A. J.; Krupp, N.; Dougherty, M. K. +14 more
Stunning aurorae are mainly produced when accelerated electrons travel along magnetic field lines to collide with the atmosphere. The motion of electrons often corresponds to the evolution of a magnetic field-aligned current system. In the terrestrial magnetosphere, the current system is formed at the night-side sector, and thus produces an aurora…
Space Telescope and Optical Reverberation Mapping Project. XIII. An Atlas of UV and X-Ray Spectroscopic Signatures of the Disk Wind in NGC 5548
Kriss, G. A.; Mehdipour, M.; Peterson, B. M. +8 more
The unusual behavior of the spectral lines of NGC5548 during the STORM campaign demonstrated a missing piece in the structure of AGNs. For a two-month period in the middle of the campaign, the spectral lines showed a deficit in flux and a reduced response to the variations of the UV continuum. This was the first time that this behavior was unequiv…
Interplanetary Shock Candidates Observed at Venus's Orbit
Wang, Yuming; Shen, Chenglong; Xu, Mengjiao +2 more
The measurements from the Venus Express spacecraft are analyzed for the basic properties of fast forward interplanetary shocks at Venus's orbit (∼0.72 au). A total of 143 fast forward interplanetary shock candidates during 2006-2014 are identified. The shock angle ΘBn, defined as the angle between the shock normal and the upstream magne…
Fast Sausage Oscillations in Coronal Loops with Fine Structures
Guo, Mingzhe; Li, Bo; Shi, Mijie
Fast sausage modes (FSMs) in flare loops have long been invoked to account for rapid quasi-periodic pulsations (QPPs) with periods of order seconds in flare lightcurves. However, most theories of FSMs in solar coronal cylinders assume a perfectly axisymmetric equilibrium, an idealized configuration apparently far from reality. In particular, it re…
Variable Stars in Local Group Galaxies. VI. The Isolated Dwarfs VV 124 and KKr 25
Sarajedini, Ata; Martínez-Vázquez, C. E.; Vivas, A. Katherina +10 more
We present the discovery of variable stars in two isolated dwarf galaxies in the outskirts of the Local Group, VV 124 and KKr 25, using observations with the Hubble Space Telescope. VV 124 hosts stellar populations with a wide range of ages (>10 Gyr until the present) and therefore we find all types of classical pulsators. In VV 124, we detect …
Near-IR Observations of the Young Star [BHB2007]-1: A Substellar Companion Opening the Gap in the Disk
Cleeves, L. Ilsedore; Garufi, Antonio; Zhu, Zhaohuan +5 more
The presence of planets or substellar objects still embedded in their native protoplanetary disks is indirectly suggested by disk substructures like gaps, cavities, and spirals. However, these companions are rarely detected. We present Very Large Telescope/NACO high-contrast images in the J, H, KS, and $L^{\prime} $ bands of the young s…
Eta Carinae: A Tale of Two Periastron Passages
Hamaguchi, Kenji; Corcoran, Michael F.; Russell, Christopher M. P. +15 more
Since 2002, the far-ultraviolet (FUV) flux (1150-1680 Å) of Eta Carinae, monitored by the Hubble Space Telescope/Space Telescope Imaging Spectrograph, has increased by an order of magnitude. This increase is attributed to partial dissipation of a line-of-sight (LOS) occulter that blocks the central core of the system. Across the 2020 February peri…