scholarly journals A model for the infrared emission from an OB star cluster environment

1991 ◽  
Vol 77 ◽  
pp. 451 ◽  
Author(s):  
D. Leisawitz
Keyword(s):  
Infrared Emission ◽  
Star Cluster ◽  
Cluster Environment

scholarly journals CAN STAR CLUSTER ENVIRONMENT AFFECT DUST INPUT FROM MASSIVE AGB STARS?

2015 ◽  
Vol 810 (2) ◽  
pp. 128 ◽  
Author(s):  
Svitlana Zhukovska ◽  
Mykola Petrov ◽  
Thomas Henning
Keyword(s):  
Star Cluster ◽  
Agb Stars ◽  
Cluster Environment

scholarly journals Star Clusters as Exotic Star Factories

2002 ◽  
Vol 187 ◽  
pp. 115-120
Author(s):  
Jarrod R. Hurley ◽  
Michael M. Shara ◽  
Christopher A. Tout
Keyword(s):  
Star Clusters ◽  
Stellar Populations ◽  
Star Cluster ◽  
Solar Neighbourhood ◽  
Cluster Environment

AbstractIn light of recent N-body simulations performed using the GRAPE-6 special-purpose hardware we discuss the role of the star cluster environment in producing unusual stellar populations and the possibility that stars labelled exotic in the solar neighbourhood may be commonplace within star clusters.

scholarly journals Triggering nuclear and galaxy activity in the Bullet cluster

2020 ◽  
Vol 634 ◽  
pp. A137
Author(s):  
S. Puccetti ◽  
F. Fiore ◽  
A. Bongiorno ◽  
K. Boutsia ◽  
R. Fassbender ◽  
...  
Keyword(s):  
Infrared Emission ◽  
Point Sources ◽  
Photometric Redshifts ◽  
X Ray ◽  
Cluster Galaxies ◽  
Star Forming ◽  
Multi Wavelength ◽  
Cluster Environment ◽  
Infrared Sources ◽  
Trigger Mechanisms

The analysis of a cluster environment is a valuable instrument to investigate the origin of gas fuelling and trigger mechanisms in active galactic nuclei (AGN) and star-forming galaxies. To this purpose, we present a detailed analysis of the point-like X-ray sources in the Bullet cluster field. Based on ∼600 ks Chandra observations, we produced a catalogue of 381 X-ray point sources up to a distance of ∼1.5 virial radius and with flux limits ∼1 × 10−16 and ∼8 × 10−16 erg cm−2 s−1 in the 0.5–2 keV and 2–10 keV bands, respectively. We find a strong (up to a factor 1.5–2) and significant (≥4σ) over-density in the full region studied 0.3R200 <  R <  1.5R200. We identified optical (R band) and infrared (Spitzer IRAC) counterparts for ∼84% and ∼48% of the X-ray sources, respectively. We obtained new spectroscopic redshifts for 106 X-ray sources and collected from the literature additional 13 spectroscopic and 8 photometric redshifts of X-ray sources. Twenty-nine X-ray sources turned out to be cluster members. Spectroscopic and photometric redshifts of optical and infrared sources were also collected, and these sources were used as ancillary samples. We used these multi-wavelength data to characterise the nature of the Bullet cluster X-ray point sources. We find that the over-density in the region 0.3R200 <  R <  R200 is likely due to X-ray AGN (mostly obscured) and star-forming galaxies associated with the cluster, while in the more external region this over-density is likely to be mostly due to background AGN. The fraction of cluster galaxies hosting an X-ray detected AGN is 1.0 ± 0.4%, which is nearly constant with the radius; this fraction is similar to that reported in other clusters of galaxies at similar redshift. The fraction of X-ray bright AGN (L2 − 10 keV >  1043 ergs s−1) in the region 0.3R200 <  R <  R200 is 0.5−0.2+0.6%, which is higher than that in other clusters at similar redshift and more similar to the AGN fraction in the field. Finally, the spatial distributions of AGN and star-forming galaxies, which we selected for their infrared emission, appear similar, thus suggesting that both are triggered by the same mechanism.

scholarly journals Probing the super star cluster environment of NGC 1569 using FISICA

2012 ◽  
Vol 428 (3) ◽  
pp. 2290-2294 ◽  
Author(s):  
D. M. Clark ◽  
S. S. Eikenberry ◽  
S. N. Raines ◽  
N. Gruel ◽  
R. Elston ◽  
...  
Keyword(s):  
Star Cluster ◽  
Cluster Environment ◽  
Ngc 1569

Detection and Characterization of earth-like Planets

1997 ◽  
Vol 161 ◽  
pp. 299-311 ◽  
Author(s):  
Jean Marie Mariotti ◽  
Alain Léger ◽  
Bertrand Mennesson ◽  
Marc Ollivier
Keyword(s):  
Direct Detection ◽  
Contrast Ratio ◽  
Angular Size ◽  
Physical Nature ◽  
Major Axis ◽  
Infrared Emission ◽  
Space Technology ◽  
Semi Major Axis ◽  
Earth Like Planets ◽  
Visible Wavelengths

AbstractIndirect methods of detection of exo-planets (by radial velocity, astrometry, occultations,...) have revealed recently the first cases of exo-planets, and will in the near future expand our knowledge of these systems. They will provide statistical informations on the dynamical parameters: semi-major axis, eccentricities, inclinations,... But the physical nature of these planets will remain mostly unknown. Only for the larger ones (exo-Jupiters), an estimate of the mass will be accessible. To characterize in more details Earth-like exo-planets, direct detection (i.e., direct observation of photons from the planet) is required. This is a much more challenging observational program. The exo-planets are extremely faint with respect to their star: the contrast ratio is about 10−10at visible wavelengths. Also the angular size of the apparent orbit is small, typically 0.1 second of arc. While the first point calls for observations in the infrared (where the contrast goes up to 10−7) and with a coronograph, the latter implies using an interferometer. Several space projects combining these techniques have been recently proposed. They aim at surveying a few hundreds of nearby single solar-like stars in search for Earth-like planets, and at performing a low resolution spectroscopic analysis of their infrared emission in order to reveal the presence in the atmosphere of the planet of CO H2O and O3. The latter is a good tracer of the presence of oxygen which could be, like on our Earth, released by biological activity. Although extremely ambitious, these projects could be realized using space technology either already available or in development for others missions. They could be built and launched during the first decades on the next century.

A New Look at Old Temples

2018 ◽  
Vol 4 (1) ◽  
pp. 52-81 ◽  
Author(s):  
Melanie Sticker-Jantscheff
Keyword(s):  
Cultural Transformation ◽  
Star Cluster ◽  
Agricultural Work ◽  
Cosmological Beliefs ◽  
Surrounding Landscape ◽  
New Look

Among the most interesting features of the provincial Roman veteran colony of Augusta Raurica (present-day Switzerland) are its sanctuaries, which were constructed during a period of profound cultural transformation. The current study examines the temples within their surrounding landscape and skyscape, to explore the possibility that their locations and orientations may bear testimony to the cosmological beliefs of the colony's inhabitants. The findings suggest that alignments with the star cluster of the Pleiades and the constellation Orion constituted a connective element between earth and sky and were used by the Gallo-Roman elites to reconcile agricultural work and seasonal festivities with new socio-political and religious requirements.

A Spatial Fading Emulator for Evaluation of MIMO Antennas in a Cluster Environment

2014 ◽  
Vol E97.B (10) ◽  
pp. 2127-2135 ◽  
Author(s):  
Tsutomu SAKATA ◽  
Atsushi YAMAMOTO ◽  
Koichi OGAWA ◽  
Hiroshi IWAI ◽  
Jun-ichi TAKADA ◽  
...  
Keyword(s):  
Mimo Antennas ◽  
Cluster Environment

Infrared Emission Spectroscopy as a Reliability Tool

1999 ◽  
Author(s):  
Q. Kim ◽  
S. Kayali
Keyword(s):  
Spatial Resolution ◽  
Emission Spectroscopy ◽  
Hot Spot ◽  
Cost Effective ◽  
Infrared Emission ◽  
Test System ◽  
Operating Conditions ◽  
Yield Enhancement ◽  
Infrared Emission Spectroscopy ◽  
Channel Temperature

Abstract In this paper, we report on a non-destructive technique, based on IR emission spectroscopy, for measuring the temperature of a hot spot in the gate channel of a GaAs metal/semiconductor field effect transistor (MESFET). A submicron-size He-Ne laser provides the local excitation of the gate channel and the emitted photons are collected by a spectrophotometer. Given the state of our experimental test system, we estimate a spectral resolution of approximately 0.1 Angstroms and a spatial resolution of approximately 0.9 μm, which is up to 100 times finer spatial resolution than can be obtained using the best available passive IR systems. The temperature resolution (&lt;0.02 K/μm in our case) is dependent upon the spectrometer used and can be further improved. This novel technique can be used to estimate device lifetimes for critical applications and measure the channel temperature of devices under actual operating conditions. Another potential use is cost-effective prescreening for determining the 'hot spot' channel temperature of devices under normal operating conditions, which can further improve device design, yield enhancement, and reliable operation. Results are shown for both a powered and unpowered MESFET, demonstrating the strength of our infrared emission spectroscopy technique as a reliability tool.

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