Search Publications
Gaussian Process Reconstruction of Reionization History
Hazra, Dhiraj Kumar; Krishak, Aditi
We reconstruct the history of reionization using Gaussian process regression. Using the UV luminosity data compilation from Hubble Frontiers Fields we reconstruct the redshift evolution of UV luminosity density and thereby the evolution of the source term in the ionization equation. This model-independent reconstruction rules out single power-law …
Broad He I 1.08-µm absorption from the obscurer in the active galaxy NGC 5548
Czerny, Bożena; Landt, Hermine; Kynoch, Daniel +2 more
The nucleus of the active galaxy NGC 5548 was the target of two intensive spectroscopic monitoring campaigns at X-ray, ultraviolet (UV), and optical frequencies in 2013/2014. These campaigns detected the presence of a massive obscuration event. In 2016/2017, Landt et al. conducted a near-IR spectroscopic monitoring campaign on NGC 5548 and discove…
The Venus Express observation of Venus' induced magnetosphere boundary at solar maximum
Zhang, T. L.; Wang, X.; Rong, Z. J. +9 more
The Venusian plasma environment is divided into two distinct regions by the induced magnetosphere boundary (IMB): the domain of solar wind protons and the domain of local planetary ions. Previous studies on the identification of the IMB gave various IMB definitions. Here we study the well-structured Venusian IMB with a sudden magnetic field rotati…
SiO Outflows as Tracers of Massive Star Formation in Infrared Dark Clouds
Caselli, Paola; Kong, Shuo; Tan, Jonathan C. +4 more
To study the early phases of massive star formation, we present ALMA observations of SiO(5-4) emission and VLA observations of 6 cm continuum emission toward 32 Infrared Dark Cloud clumps, spatially resolved down to ≲0.05 pc. Out of the 32 clumps, we detect SiO emission in 20 clumps, and in 11 of them the SiO emission is relatively strong and like…
SOFIA-upGREAT Imaging Spectroscopy of the [C II] 158 µm Fine-structure Line of the Sgr B Region in the Galactic Center
Harris, A. I.; Morris, M. R.; Stutzki, J. +8 more
We report SOFIA-upGREAT spectroscopic imaging of the [C II] 158 µm spectral line, as well as a number of [O I] 63 µm spectra, across a 67 × 45 pc field toward the Sgr B region in our Galactic center. The fully sampled and velocity-resolved [C II] images have 0.55 pc spatial and 1 km s-1 velocity resolutions. We find that Sgr…
The Second Earth Trojan 2020 XL5
Tholen, David J.; Hui, Man-To; Wiegert, Paul A. +1 more
The Earth Trojans are coorbitals librating around the Lagrange points L 4 or L 5 of the Sun-Earth system. Although many numerical studies suggest that they can maintain their dynamical status and be stable on timescales up to a few tens of thousands of years or even longer, they remain an elusive population. Thus far only one…
On the partial eruption of a bifurcated solar filament structure
Liu, Jiajia; Uddin, Wahab; Chandra, Ramesh +4 more
The partial eruption of a filament channel with bifurcated substructures is investigated using data sets obtained from both ground-based and space-borne facilities. Small-scale flux reconnection/cancellation events in the region triggered the pile-up of ambient magnetic field, observed as bright extreme ultraviolet (EUV) loops in close proximity t…
Testing the chemical homogeneity of chemically tagged dissolved birth clusters
Bovy, Jo; Cheng, Chloe M.; Price-Jones, Natalie
Chemically tagging stars back to common formation sites in the Milky Way and establishing a high level of chemical homogeneity in these chemically tagged birth clusters is crucial for understanding the chemical and dynamical history of the Galactic disc. We constrain the intrinsic abundance scatter in 17 newly chemically tagged dissolved birth clu…
The Decline and Fall of the Youngest Planetary Nebula
Balick, Bruce; Guerrero, Martín A.; Ramos-Larios, Gerardo
The Stingray Nebula, a.k.a. Hen3-1357, appeared for the first time in 1990 when bright nebular lines and radio emission that had not been observed before were unexpectedly discovered. In the ensuing years, the nebula faded precipitously. We report changes in shape and large decreases in its nebular emission-line fluxes based on well-calibrated ima…
NGC 6611 601: a hot pre-main-sequence spectroscopic binary containing a centrifugal magnetosphere host star
Wade, G. A.; Shultz, M. E.; Alecian, E. +5 more
W 601 (NGC 6611 601) is one of the handful of known magnetic Herbig Ae/Be stars. We report the analysis of a large data set of high-resolution spectropolarimetry. The star is a previously unreported spectroscopic binary, consisting of two B2 stars with a mass ratio of 1.8, masses of 12 and 6.2 M⊙, in an eccentric 110-d orbit. The magnet…