Results 121 to 130 of about 4,877 (221)

Millimeter wave radiometry as a means of determining cometary surface and subsurface temperature [PDF]

Thermal emission spectra for a variety of cometary nucleus models were evaluated by a radiative transfer technique adapted from modeling of terrestrial ice and snow fields.
Brandt, J. C., Hobbs, R. W., Maran, S. P.   +2 more
core   +1 more source

The Evolution in Coma Molecular Composition of Comet C/2017 K2 (PanSTARRS) across the H2O Sublimation Zone: ALMA Imaging of a H2O-dominated Coma

The Planetary Science Journal
We report a survey of molecular emission from cometary volatiles using the Atacama Large Millimeter/submillimeter Array toward comet C/2017 K2 (PanSTARRS) carried out on UT 2022 September 21, 22, and 23 at a heliocentric distance ( r _H ) of 2.1 au ...
Nathan X. Roth, Stefanie N. Milam, Martin A. Cordiner, Anthony J. Remijan, Dominique Bockelée-Morvan, Nicolas Biver, Jérémie Boissier, Steven B. Charnley, Charles E. Woodward, Lillian X. Hart, Timothy N. Proudkii   +10 more
doaj   +1 more source

Scientific returns from a program of space missions to comets [PDF]

A program of cometary missions is proposed. The nature and size of interstellar dust, its origin and evolution; identification of new interstellar molecules; clarification of interstellar chemistry; accretion of grains into protosolar cometesimals; role ...
Delsemme, A. H.
core   +1 more source

NEOWISE Observations of Distant Active Long-period Comets C/2014 B1 (Schwartz), C/2017 K2 (Pan-STARRS), and C/2010 U3 (Boattini)

The Astronomical Journal
Hyperactive comet activity typically becomes evident beyond the frost line (∼3–4 au) where it becomes too cold for water-ice to sublimate. If carbon monoxide (CO) and carbon dioxide (CO _2 ) are the species that drive activity at sufficiently large ...
Dave G. Milewski, Joseph R. Masiero, Jana Pittichová, Emily A. Kramer, Amy K. Mainzer, James M. Bauer   +5 more
doaj   +1 more source

Formation of Polyoxymethylenes in Extraterrestrial Ice Analogs of Formaldehyde Exposed to Ionizing Radiation

The Astrophysical Journal
Polyoxymethylenes (POMs) have long been hypothesized as key organics in comets, as their decomposition products could account for the possible extended cometary formaldehyde (H _2 CO) source.
Qi’ang Gong, Xilin Bai, Jinghui Lu, Jiuzhong Yang, Yang Pan, Zhenrong Sun, Ralf I. Kaiser, Tao Yang   +7 more
doaj   +1 more source

Brightness Behavior of Distant Oort Cloud Comets

The Planetary Science Journal
Dynamically new comets provide important insights into the conditions of the presolar nebula and its evolution, as they are believed to have experienced minimal solar heating before their discovery.
Carrie E. Holt, Matthew M. Knight, Michael S. P. Kelley, Tim Lister, Quanzhi Ye, Colin Snodgrass, Cyrielle Opitom, Rosita Kokotanekova, Megan E. Schwamb, Matthew M. Dobson, Michele T. Bannister, Marco Micheli, Stefanie N. Milam, Derek C. Richardson, The LCO Outbursting Objects Key (LOOK) Project, Edward Gomez, Joseph P. Chatelain, Sarah Greenstreet   +17 more
doaj   +1 more source

Competitive Entrapment of Hypervolatiles in Interstellar and Cometary Water Ice Analogs

The Astrophysical Journal
The distribution of chemical species in protoplanetary disks around young stars, especially their division between gas and solid phases, fundamentally shapes the composition of future planets and planetesimals.
Qijia Zhou, Alexia Simon, Karin I. Öberg, Mahesh Rajappan   +3 more
doaj   +1 more source

Prospectivity Modeling of the NASA VIPER Landing Site at Mons Mouton near the Lunar South Pole

The Planetary Science Journal
We use a high-resolution digital elevation model and a numerical thermal model to produce a variety of inputs for a water-ice prospectivity model for the Volatiles Investigating Polar Exploration Rover (VIPER) landing site.
Joshua Coyan, Matt Siegler, Jose Martinez-Comacho, Ross Beyer, Mark Shirley   +4 more
doaj   +1 more source

The Volatile Inventory of 3I/ATLAS as Seen with JWST/MIRI

The Astrophysical Journal Letters
We present the first spectroscopic characterization of an interstellar object at mid-infrared wavelengths. Postperihelion observations of 3I/ATLAS (3I) using the JWST/MIRI medium-resolution spectrometer were obtained on 2025 December 15–16 and 27, when ...
Matthew Belyakov, Ian Wong, Bryce T. Bolin, M. Ryleigh Davis, Steven J. Bromley, Carey M. Lisse, Michael E. Brown   +6 more
doaj   +1 more source

From linoleic acid to hexanal and hexanol by whole cell catalysis with a lipoxygenase, hydroperoxide lyase and reductase cascade in Komagataella phaffii. [PDF]

Front Mol Biosci, 2022
Hashem C, Hochrinner J, Bürgler MB, Rinnofner C, Pichler H, Winkler M.   +5 more
europepmc   +1 more source