THE ROLE OF LOW MASS NUCLEON RESONANCES IN NEAR THRESHOLD ω MESON PHOTOPRODUCTION

2002 ◽  
Author(s):  
ALEXANDER I. TITOV ◽  
T.-S. HARRY LEE
Keyword(s):  
Meson Photoproduction ◽  
Nucleon Resonances ◽  
Low Mass ◽  
Near Threshold

scholarly journals Role of nucleon resonances on η-meson photoproduction

2020 ◽  
Author(s):  
D. Aprilina ◽  
A. Salam ◽  
I. Fachruddin
Keyword(s):  
Meson Photoproduction ◽  
Nucleon Resonances

scholarly journals The Circumstellar Environment of Embedded Massive Stars

2002 ◽  
Vol 12 ◽  
pp. 143-145 ◽  
Author(s):  
Lee G. Mundy ◽  
Friedrich Wyrowski ◽  
Sarah Watt
Keyword(s):  
Massive Star ◽  
Massive Stars ◽  
Low Mass Stars ◽  
Submillimeter Wavelength ◽  
Star Forming ◽  
Star Forming Regions ◽  
Low Mass ◽  
Circumstellar Environments ◽  
Near Future

Millimeter and submillimeter wavelength images of massive star-forming regions are uncovering the natal material distribution and revealing the complexities of their circumstellar environments on size scales from parsecs to 100’s of AU. Progress in these areas has been slower than for low-mass stars because massive stars are more distant, and because they are gregarious siblings with different evolutionary stages that can co-exist even within a core. Nevertheless, observational goals for the near future include the characterization of an early evolutionary sequence for massive stars, determination if the accretion process and formation sequence for massive stars is similar to that of low-mass stars, and understanding of the role of triggering events in massive star formation.

scholarly journals TiNy TITANS: THE ROLE OF DWARF–DWARF INTERACTIONS IN LOW-MASS GALAXY EVOLUTION

2015 ◽  
Vol 805 (1) ◽  
pp. 2 ◽  
Author(s):  
S. Stierwalt ◽  
G. Besla ◽  
D. Patton ◽  
K. Johnson ◽  
N. Kallivayalil ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Low Mass

scholarly journals The Role of Discs in the Collapse and Fragmentation of Prestellar Cores

2016 ◽  
Vol 33 ◽  
Author(s):  
O. Lomax ◽  
A. P. Whitworth ◽  
D. A. Hubber
Keyword(s):  
Kinetic Energy ◽  
Smoothed Particle Hydrodynamics ◽  
Low Mass Stars ◽  
Gravitational Instabilities ◽  
Disc Material ◽  
Prestellar Cores ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Low Mass

AbstractDisc fragmentation provides an important mechanism for producing low-mass stars in prestellar cores. Here, we describe smoothed particle hydrodynamics simulations which show how populations of prestellar cores evolve into stars. We find the observed masses and multiplicities of stars can be recovered under certain conditions.First, protostellar feedback from a star must be episodic. The continuous accretion of disc material on to a central protostar results in local temperatures which are too high for disc fragmentation. If, however, the accretion occurs in intense outbursts, separated by a downtime of ~ 104yr, gravitational instabilities can develop and the disc can fragment.Second, a significant amount of the cores’ internal kinetic energy should be in solenoidal turbulent modes. Cores with less than a third of their kinetic energy in solenoidal modes have insufficient angular momentum to form fragmenting discs. In the absence of discs, cores can fragment but results in a top-heavy distribution of masses with very few low-mass objects.

scholarly journals Footprints of triggering in large area surveys of the nearby ISM and YSOs

2006 ◽  
Vol 2 (S237) ◽  
pp. 124-127
Author(s):  
L. Viktor Tóth ◽  
Zoltán T. Kiss
Keyword(s):  
Star Formation ◽  
Stellar Evolution ◽  
Large Area ◽  
Large Sample ◽  
Low Mass ◽  
Cold Core

AbstractOur goal is to evaluate the role of triggering effects on the star formation and early stellar evolution by presenting a statistically large sample of cloud and low-mass YSO data. We conducted large area surveys (ranging from 400 square-degree to 10800 square-degree) in optical, NIR and FIR. The distribution of the ISM and low-mass YSOs were surveyed. A relative excess was found statistically in the number of dense and cold core bearing clouds and low mass YSOs in the direction of the FIR loop shells indicating a possible excess in their formation.

scholarly journals K0SΣ0 photoproduction at the BGO-OD experiment

2020 ◽  
Vol 241 ◽  
pp. 01009
Author(s):  
Katrin Kohl ◽  
Stefan Alef ◽  
Patrick Bauer ◽  
Reinhard Beck ◽  
Alessandro Braghieri ◽  
...  
Keyword(s):  
Vector Meson ◽  
Momentum Transfer ◽  
Cross Section ◽  
Photon Beam ◽  
Bremsstrahlung Photon ◽  
Meson Photoproduction ◽  
Accelerator Facility ◽  
Transfer Processes

The BGO-OD experiment at the ELSA accelerator facility uses an energy tagged bremsstrahlung photon beam to investigate the excitation structure of the nucleon via meson photoproduction. The setup with a BGO calorimeter surrounding the target and an open dipole spectrometer covering the for ward region is ideally suited for investigating low momentum transfer processes, in particular in strangeness photoproduction. The associated photoproduction of K0S and hyperons is essential to understand the role of K* exchange mech anisms. A cusp-like structure observed in the yp → K0SΣ+ reaction at the K* threshold is described by models including dynamically generated resonances from vector meson-baryon interactions. Such interactions are pre dicted to give a peak like structure in K0SΣ0 photoproduction off the neutron. A very preliminary cross section is determined and compared to the prediction, the results appear to support the model

scholarly journals Eccentricity distribution of wide low-mass binaries

2020 ◽  
Vol 496 (1) ◽  
pp. 987-993 ◽  
Author(s):  
Andrei Tokovinin
Keyword(s):  
Stellar Dynamics ◽  
Statistical Information ◽  
Solar Neighbourhood ◽  
Wide Binary ◽  
Eccentric Orbits ◽  
Wide Pairs ◽  
Low Mass ◽  
Orbital Periods ◽  
Relative Motions

ABSTRACT Distribution of eccentricities of very wide (up to 10 kau) low-mass binaries in the solar neighbourhood is studied using the catalogue of El-Badry and Rix (2018) based on Gaia. Direction and speed of relative motions in wide pairs contain statistical information on the eccentricity distribution, otherwise inaccessible owing to very long orbital periods. It is found that the eccentricity distribution is close to the linear (thermal) one f(e) = 2e. However, pairs with projected separations <200 au have less eccentric orbits, while f(e) for wide pairs with s > 1 kau appears to be slightly superthermal, with an excess of very eccentric orbits. Eccentricity of any wide binary can be constrained statistically using direction and speed of its motion. The thermal eccentricity distribution signals an important role of the stellar dynamics in the formation of wide binaries, although disc-assisted capture also can produce such pairs with eccentric orbits.

scholarly journals The less significant role of large-scale environment than optical AGN in nearby, isolated elliptical galaxies

2018 ◽  
Vol 620 ◽  
pp. A117 ◽  
Author(s):  
I. Lacerna ◽  
M. Argudo-Fernández ◽  
S. Duarte Puertas
Keyword(s):  
Large Scale ◽  
Formation Rate ◽  
Elliptical Galaxies ◽  
Stellar Mass ◽  
Mass Scale ◽  
Strength Parameter ◽  
Primary Role ◽  
Isolated Galaxies ◽  
Low Mass

Context. The formation and evolution of elliptical galaxies in low-density environments are less understood than classical elliptical galaxies in high-density environments. Isolated galaxies are defined as galaxies without massive neighbors within scales of galaxy groups. The effect of the environment at several Mpc scales on their properties has been barely explored. We study the role of the large-scale environment in 573 isolated elliptical galaxies out to z = 0.08. Aims. We aim to explore whether the large-scale environment affects some of the physical properties of the isolated galaxies studied in this work. Methods. We used three environmental estimators of the large-scale structure within a projected radius of 5 Mpc around isolated galaxies: the tidal strength parameter, projected density ηk,LSS, and distance to the fifth nearest neighbor galaxy. We studied isolated galaxies regarding stellar mass, integrated optical g − i color, specific star formation rate (sSFR), and emission lines. Results. We find 80% of galaxies at lower densities correspond to “red and dead” elliptical galaxies. Blue and red galaxies do not tend to be located in different environments according to ηk,LSS. Almost all the isolated ellipticals in the densest large-scale environments are red or quenched, of which a third are low-mass galaxies. The percentage of isolated elliptical galaxies located in the active galactic nucleus (AGN) region of the BPT diagram is 64%. We identified 33 blue, star-forming (SF) isolated ellipticals using both color and sSFR. Half of these are SF nuclei in the BPT diagram, which amounts to 5% of the galaxies in this diagram. Conclusions. The large-scale environment does not play the primary role in determining the color or sSFR of isolated elliptical galaxies. The large-scale environment seems to be negligible from a stellar mass scale around 1010.6 M⊙, probably because of the dominant presence of AGN at higher masses. For lower masses, the processes of cooling and infall of gas from large scales are very inefficient in ellipticals. Active galactic nuclei might also be an essential ingredient to keep most of the low-mass isolated elliptical galaxies quenched.

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