Results 71 to 80 of about 5,191,368 (191)

Deep Space Network Radio Science and Ground‐Based Planetary Radar in the Next Decade

Radio Science, Volume 60, Issue 7, July 2025.
Abstract The Deep Space Network (DSN) has been a core operational element of NASA's crewed and robotic exploration of the Solar System since the early 1960s. The primary role of the DSN has been to acquire telemetry and navigation data, but over the years, its radiometric and radar capabilities have expanded to form a system for obtaining unique ...
R. S. Park, J. E. Riedel, N. Rodriguez‐Alvarez, M. Brozovic, L. A. M. Benner, P. Vergados, D. Buccino, C. S. Jacobs, L. S. Locke, S. W. Asmar, R. Castano, T. J. W. Lazio, J. Jao, C. Lee   +13 more
wiley   +1 more source

The Twice-Overlooked, Second Fanaroff-Riley II Broad Absorption Line Quasar LBQS 1138-0126

, 2002
International audienceWe report the correct classification of an overlooked Fanaroff-Riley class II radio-loud quasar with broad absorption lines, only the second such object so identified.
Gregg, Michael D., de Breuck, Carlos, Croom, Scott M., Brotherton, Michael S., Becker, Robert H.   +4 more
core   +1 more source

The COS CGM Compendium. V. The Dichotomy of O vi Associated with Low- and High-metallicity Cool Gas at z < 1

The Astrophysical Journal
We analyze the O vi content and kinematics for 126 H i -selected absorbers at 0.14 ≲ z ≲ 0.73 for which the metallicities of their cool photoionized phase have been determined. We separate the absorbers into 100 strong Ly α forest systems (SLFSs with 15 ≲
Sameer, Nicolas Lehner, J. Christopher Howk, Andrew J. Fox, John M. O’Meara, Benjamin D. Oppenheimer   +5 more
doaj   +1 more source

Redshift‐Agnostic Machine Learning Classification: Unveiling Peak Performance in Galaxy, Star, and Quasar Classification (Using SDSS DR17)

Astronomische Nachrichten, Volume 346, Issue 5, June 2025.
ABSTRACT Classification of galaxies, stars, and quasars using spectral data is fundamental to astronomy, but often relies heavily on redshift. This study evaluates the performance of 10 machine learning algorithms on SDSS data to classify these objects, with a particular focus on scenarios where redshift information is unavailable.
Debashis Chatterjee, Prithwish Ghosh
wiley   +1 more source

Introduction to X-Ray Absorption Spectroscopy

, 2016
X-ray Absorption Spectroscopy (XAS) is a well-established analytical technique used extensively for the characterization of semiconductors in solid or liquid, crystalline or amorphous, bulk or nanoscale form.
Ridgway, Mark C, Schnohr, Claudia
core   +1 more source

Probing the He ii Reionization ERa via Absorbing C iv Historical Yield (HIERACHY). IV. A Complex Redshifted Absorption System Intrinsic to Quasar

The Astrophysical Journal
High-resolution spectra provide a powerful tool in studying the associated absorption lines in quasars. We present a case study of the quasar J014741-030247 at z  ∼  4.75, which hosts complex intrinsic absorption lines revealed by the high-resolution ...
Huiyang Mao, Jiang-Tao Li, Xiaodi Yu, Zhijie Qu, Weizhe Liu, Li Ji   +5 more
doaj   +1 more source

The CIViL* Survey: The Discovery of a C iv Dichotomy in the Circumgalactic Medium of L* Galaxies

The Astrophysical Journal Letters
This paper investigates C iv absorption in the circumgalactic medium (CGM) of L ^⋆ galaxies and its relationship with galaxy star formation rates. We present new observations from the C iv in L ^⋆ galaxies survey (PID # 17076) using the Hubble Space ...
Samantha L. Garza, Jessica K. Werk, Trystyn A. M. Berg, Yakov Faerman, Benjamin D. Oppenheimer, Rongmon Bordoloi, Sara L. Ellison   +6 more
doaj   +1 more source

MUSEQuBES: Unveiling Cosmic Web Filaments at z ≈ 3.6 through Dual Absorption and Emission Line Analysis

The Astrophysical Journal Letters
According to modern cosmological models, galaxies are embedded within cosmic filaments, which supply a continuous flow of pristine gas, fueling star formation and driving their evolution. However, due to their low density, the direct detection of diffuse
Eshita Banerjee, Sowgat Muzahid, Joop Schaye, Sebastiano Cantalupo, Sean D. Johnson   +4 more
doaj   +1 more source

Neutral atomic-carbon quasar absorption-line systems at

, 2015
We present the results of a search for cold gas at high redshift along quasar lines of sight carried out without any a priori assumption on the neutral atomic-hydrogen content of the absorption-line systems.
Petitjean, P., R. Srianand, Noterdaeme, P., Srianand, R., P. Noterdaeme, P. Petitjean, C. Ledoux, Ledoux, C.   +7 more
core   +1 more source

Highly Ionized Gas in the Zone of Avoidance: Using the CIViL⋆ Survey to Pinpoint Physical Conditions of Gaseous Halos

The Astrophysical Journal
This paper investigates the physical conditions of the circumgalactic medium of L ^⋆ galaxies through explorations of observed ion tracer gas kinematics and comparisons of observations to different ionization models.
Samantha L. Garza, Yakov Faerman, Trystyn A. M. Berg, Jessica K. Werk, Benjamin D. Oppenheimer, Rongmon Bordoloi, Sara Ellison   +6 more
doaj   +1 more source