Results 11 to 20 of about 4,978 (213)

The Rate, Amplitude, and Duration of Outbursts from Class 0 Protostars in Orion

The Astrophysical Journal Letters, 2022
At least half of a protostar’s mass is accreted in the Class 0 phase, when the central protostar is deeply embedded in a dense, infalling envelope. We present the first systematic search for outbursts from Class 0 protostars in the Orion clouds.
Wafa Zakri, S. T. Megeath, William J. Fischer, Robert Gutermuth, Elise Furlan, Lee Hartmann, Nicole Karnath, Mayra Osorio, Emily Safron, Thomas Stanke, Amelia M. Stutz, John J. Tobin, Thomas S. Allen, Sam Federman, Nolan Habel, P. Manoj, Mayank Narang, Riwaj Pokhrel, Luisa Rebull, Patrick D. Sheehan, Dan M. Watson   +20 more
doaj   +1 more source

CO in Protostars (COPS): Herschel-SPIRE Spectroscopy of Embedded Protostars^∗ [PDF]

The Astrophysical Journal, 2018
Abstract We present full spectral scans from 200 to 670 μm of 26 Class 0+I protostellar sources obtained with Herschel-SPIRE as part of the “COPS-SPIRE” Open Time program, complementary to the DIGIT and WISH Key Programs. Based on our nearly continuous, line-free spectra from 200 to 670 μm, the calculated bolometric luminosities (L
Yao-Lun Yang, Joel D. Green, Neal J. Evans II, Jeong-Eun Lee, Jes K. Jørgensen, Lars E. Kristensen, Joseph C. Mottram, Gregory Herczeg, Agata Karska, Odysseas Dionatos, Edwin A. Bergin, Jeroen Bouwman, Ewine F. van Dishoeck, Tim A. van Kempen, Rebecca L. Larson, Umut A. Yıldız   +15 more
openaire   +8 more sources

Pulsed accretion in a variable protostar [PDF]

Nature, 2013
Periodic increases in luminosity arising from variable accretion rates have been predicted for some close pre-main sequence binary stars as they grow from circumbinary disks. The phenomenon is known as "pulsed accretion" and can affect the orbital evolution and mass distribution of young binaries, as well as the potential for planet formation in the ...
Muzerolle, James, Furlan, Elise, Flaherty, Kevin, Balog, Zoltan, Gutermuth, Robert   +4 more
openaire   +3 more sources

Protostar Formation in the Early Universe [PDF]

Science, 2008
The nature of the first generation of stars in the universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability.
Yoshida, N., Omukai, K., Hernquist, L.
openaire   +6 more sources

Signatures of UV radiation in low-mass protostars [PDF]

, 2021
Context. Ultraviolet radiation (UV) influences the physics and chemistry of star-forming regions, but its properties and significance in the immediate surroundings of low-mass protostars are still poorly understood. Aims.
Karska, Agata, Lars E. Kristensen, Daniel Harsono, Gładkowski, Marcin, Tychoniec, Lukasz, Michał Żółtowski, Harsono, Daniel, Żółtowski, Michał, Miguel Figueira, Gronowski, M., Żółtowski, M., Gladkowski, Marcin, Łukasz Tychoniec, Agnieszka Mirocha, Mirocha, Agnieszka, Tychoniec, Łukasz, Kristensen, L.E., Karska, A., Kristensen, Lars E., Gronowski, Marcin, Tychoniec, L., Zoltowski, Michal, Marcin Gładkowski, Gładkowski, M., Agata Karska, Harsono, D., Figueira, Miguel, Mirocha, A., Figueira, M., Marcin Gronowski   +29 more
core   +1 more source

Kinetics of the tautomerization of thioimidic acids R−C(SH)NH → R−C(S)NH2: For R = H, F, HO, CN, NC, H2N, HC(O), HC(S), HC≡ C, CH3, CF3, H2C=CH, HOCH2, H2NCH2,CH3C(O), C2H5, (CH3)2CH, C6H5

International Journal of Chemical Kinetics, Volume 55, Issue 11, Page 731-742, November 2023., 2023
Abstract The kinetics of the tautomerization of thio‐imidic acids RC(SH)NH were determined at low (50–300 K) and high (500–1500 K) temperatures as R was varied to encompass mono‐ and diatomic species H, F, HO, NC, CN through H2N, HC(O), HC(S), HC≡ C, H3C, F3C, HOCH2, H2C=CH, CH3C(O), H2NCH2 and including ethyl, isopropyl and phenyl groups. The presence
Judith Würmel, John M. Simmie
wiley   +1 more source

Bulk mineralogy, water abundance, and hydrogen isotope composition of unequilibrated ordinary chondrites

Meteoritics &Planetary Science, Volume 58, Issue 9, Page 1365-1381, September 2023., 2023
Abstract The origin and transport of water in the early Solar System is an important topic in both astrophysics and planetary science, with applications to protosolar disk evolution, planetary formation, and astrobiology. Of particular interest for understanding primordial water transport are the unequilibrated ordinary chondrites (UOCs), which have ...
Helen Grant, Romain Tartèse, Rhian Jones, Laurette Piani, Yves Marrocchi, Ashley King, Thomas Rigaudier   +6 more
wiley   +1 more source

Loading of Amino Acids onto RNA in a Putative RNA‐Peptide World

Angewandte Chemie International Edition, Volume 62, Issue 21, May 15, 2023., 2023
The loading of RNAs with amino acids constitutes the first step toward RNA‐based peptide synthesis in a putative prebiotic RNA‐peptide world. The efficient loading of RNA strands incorporating N‐methylcarbamoyl nucleotides with a series of amino acids is reported. The loaded RNA strands also underwent RNA‐based amino acid transfer reactions.
Johannes N. Singer, Felix M. Müller, Ewa Węgrzyn, Christina Hölzl, Hans Hurmiz, Chuyi Liu, Luis Escobar, Thomas Carell   +7 more
wiley   +1 more source

The grain size distribution of matrix in primitive chondrites

Meteoritics &Planetary Science, Volume 58, Issue 5, Page 688-704, May 2023., 2023
Abstract The matrix of primitive chondrites is composed of submicron crystals embedded in amorphous silicates. These grains are thought to be the remains of relatively unprocessed dust from the inner regions of the protoplanetary disk. The matrix of primitive meteorites is often compared to chondritic porous interplanetary dust particles (CP‐IDPs ...
E. Vaccaro, P. Wozniakiewicz, I. A. Franchi, N. Starkey, S. S. Russell   +4 more
wiley   +1 more source

300: An ACA 870 μm Continuum Survey of Orion Protostars and Their Evolution

The Astrophysical Journal, 2023
We present an 870 μ m continuum survey of 300 protostars from the Herschel Orion Protostar Survey using the Atacama Compact Array (ACA). These data measure protostellar flux densities on envelope scales ≤8000 au (20″) and resolve the structure of ...
Samuel Federman, S. Thomas Megeath, John J. Tobin, Patrick D. Sheehan, Riwaj Pokhrel, Nolan Habel, Amelia M. Stutz, William J. Fischer, Lee Hartmann, Thomas Stanke, Mayank Narang, Mayra Osorio, Prabhani Atnagulov, Rohan Rahatgaonkar   +13 more
doaj   +1 more source