scholarly journals The K-Band Wide Field Survey: Understanding the Local Galaxies

1998 ◽  
Vol 179 ◽  
pp. 281-284
Author(s):  
J. Huang
Keyword(s):  
High Precision ◽  
Field Survey ◽  
Mass Density ◽  
Wide Field ◽  
True Value ◽  
Magnitude Range ◽  
Local Measurements ◽  
Number Counts ◽  
Total Coverage ◽  
K Band

We have conducted a wide-field K-selected galaxy survey with complementary optical I- and B-band imaging in six fields with a total coverage of 9.8 square degrees (Huang et al. 1997). The observations were carried out on the UH 0.6m and the UH 2.2m telescopes. The purpose of this survey is to study the properties of the local galaxies and explore the evolution of K-selected galaxies at low redshifts. Star-galaxy discrimination is performed using both galaxy color properties and object morphologies, and 6264 galaxies are found. This survey establishes the bright-end K-band galaxy number counts in the magnitude range 13 < K < 16 with high precision. We find that our bright-end counts have a significantly steeper slope than the prediction of a no-evolution model, which cannot be accounted for by observational or theoretical error. Since it is very unlikely that there is sufficient evolution at such low redshifts to account for this effect, we argue that there is a local deficiency of galaxies by a factor of 2 on scale sizes of around 300 Mpc. This would imply that local measurements of Ω0 underestimate the true value of the cosmological mass density by this factor and that local measurements of H0 could be high by as much as 33%.

scholarly journals The Chandra Deep Wide-field Survey: A New Chandra Legacy Survey in the Boötes Field. I. X-Ray Point Source Catalog, Number Counts, and Multiwavelength Counterparts

2020 ◽  
Vol 251 (1) ◽  
pp. 2
Author(s):  
Alberto Masini ◽  
Ryan C. Hickox ◽  
Christopher M. Carroll ◽  
James Aird ◽  
David M. Alexander ◽  
...  
Keyword(s):  
Point Source ◽  
Field Survey ◽  
Wide Field ◽  
X Ray ◽  
Catalog Number ◽  
Number Counts ◽  
Point Source Catalog

Design and verification of high-precision multi-star simulator with a wide field of view

2020 ◽  
Vol 13 (6) ◽  
pp. 1-9
Author(s):  
XU Hong-gang ◽  
◽  
HAN Bing ◽  
LI Man-li ◽  
MA Hong-tao ◽  
...  
Keyword(s):  
High Precision ◽  
Field Of View ◽  
Wide Field ◽  
Wide Field Of View

scholarly journals A Wide‐Field Survey of Twoz∼ 0.5 Galaxy Clusters: Identifying the Physical Processes Responsible for the Observed Transformation of Spirals into S0s

2007 ◽  
Vol 671 (2) ◽  
pp. 1503-1522 ◽  
Author(s):  
Sean M. Moran ◽  
Richard S. Ellis ◽  
Tommaso Treu ◽  
Graham P. Smith ◽  
R. Michael Rich ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Field Survey ◽  
Wide Field ◽  
Physical Processes

scholarly journals Resolved Stellar Populations of the interacting galaxies of the M81 group

2016 ◽  
Vol 11 (S321) ◽  
pp. 22-24
Author(s):  
Sakurako Okamoto ◽  
Nobuo Arimoto ◽  
Annette M.N. Ferguson ◽  
Edouard J. Bernard ◽  
Mike J. Irwin ◽  
...  
Keyword(s):  
Main Sequence ◽  
Field Survey ◽  
State Of The Art ◽  
Young Stars ◽  
Interacting Galaxies ◽  
Wide Field ◽  
Red Giant ◽  
Tidal Streams ◽  
Stellar Associations ◽  
First Time

AbstractWe present the results from the state-of-the-art wide-field survey of the M81 galaxy group that we are conducting with Hyper Suprime-Cam on Subaru Telescope. Our photometry reaches about 2 mag below the tip of the red giant branch (RGB) and reveals the spatial distribution of both old and young stars over an area of 5°2around the M81. The young main-sequence (MS) stars closely follow the HI distribution and can be found in a stellar stream between M81 and NGC 3077 and in numerous outlying stellar associations. Our survey also reveals for the first time the very extended (>2 × R25) halos of RGB stars around M81, M82, and NGC 3077, as well as faint tidal streams that link these systems. The gravitational interactions between M81, M82 and NGC 3077 galaxies induced star formation in tidally stripped gas, and also significantly perturbed the older stellar components leading to disturbed halo morphologies.

scholarly journals Looking towards the detection of exoearths with SuperWASP

2006 ◽  
Vol 5 (3) ◽  
pp. 183-186
Author(s):  
R.A. Street ◽  
D.J. Christian ◽  
W.I. Clarkson ◽  
A.C. Cameron ◽  
B. Enoch ◽  
...  
Keyword(s):  
South African ◽  
Field Survey ◽  
Astronomical Observatory ◽  
Wide Field ◽  
La Palma ◽  
Automated Algorithm ◽  
First Results ◽  
Gravitational Pull ◽  
Low Amplitude ◽  
Host Stars

The WASP consortium is conducting an ultra-wide field survey of stars between 8–15 mag from both hemispheres. Our primary science goal is to detect extra-solar ‘hot-Jupiter’-type planets that eclipse (or transit) bright host stars and for which further detailed investigation will be possible. We summarize the design of the SuperWASP instruments and describe the first results from our northern station SW-N, sited in La Palma, Canary Islands. Our second station, which began operations this year, is located at the South African Astronomical Observatory. Between April and September, 2004, SW-N continuously observed ~6.7 million stars. The consortium's custom-written, fully automated data reduction pipeline has been used to process these data, and the information is now stored in the project archive, held by the Leicester database and archive service (LEDAS). We have applied a sophisticated, automated algorithm to identify the low-amplitude (~0.01 mag), brief (~few hours) signatures of transiting exoplanets. In addition, we have assessed each candidate in the light of all available catalogue information in order to reject data artefacts and astrophysical false positive detections. The highest priority candidates are currently being subjected to further observations in order to select the true planets. Once the exoplanets are confirmed, a host of exciting opportunities are open to us. In this paper, we describe two techniques that exploit the transits in order to detect other objects within the same system. The first involves determining precise epochs for a sequence of transit events in order to detect the small timing variations caused by the gravitational pull of other planets in the same system. The second method employs ultra-high precision photometry of the transits to detect the deviations caused by the presence of exoplanetary moons. Both of these techniques are capable of detecting objects the size of terrestrial planets.

The K-Band Luminosity Function of Galaxies

1998 ◽  
Vol 179 ◽  
pp. 278-280
Author(s):  
J. P. Gardner ◽  
R. M. Sharples ◽  
C. S. Frenk ◽  
B. E. Carrasco
Keyword(s):  
Luminosity Function ◽  
Near Infrared ◽  
Mass Function ◽  
Solar Mass ◽  
The Galaxy ◽  
Statistical Studies ◽  
The Absolute ◽  
Number Counts ◽  
Luminosity Evolution ◽  
K Band

The luminosity function of galaxies is central to many problems in cosmology, including the interpretation of faint number counts. The near-infrared provides several advantages over the optical for statistical studies of galaxies, including smooth and well-understood K-corrections and expected luminosity evolution. The K–band is dominated by near-solar mass stars which make up the bulk of the galaxy. The absolute K magnitude is a measure of the visible mass in a galaxy, and thus the K–band luminosity function is an observational counterpart of the mass function of galaxies.

scholarly journals Considerations for atmospheric retrieval of high-precision brown dwarf spectra

2020 ◽  
Vol 497 (4) ◽  
pp. 5136-5154
Author(s):  
Anjali A A Piette ◽  
Nikku Madhusudhan
Keyword(s):  
High Precision ◽  
Thermal Emission ◽  
Simulated Data ◽  
Brown Dwarfs ◽  
High Signal ◽  
Temperature Structure ◽  
Wide Field ◽  
Brown Dwarf ◽  
Data Set ◽  
Stellar Objects

ABSTRACT Isolated brown dwarfs provide remarkable laboratories for understanding atmospheric physics in the low-irradiation regime, and can be observed more precisely than exoplanets. As such, they provide a glimpse into the future of high-signal-to-noise ratio (SNR) observations of exoplanets. In this work, we investigate several new considerations that are important for atmospheric retrievals of high-quality thermal emission spectra of sub-stellar objects. We pursue this using an adaptation of the h y dra atmospheric retrieval code. We propose a parametric pressure–temperature (P–T) profile for brown dwarfs consisting of multiple atmospheric layers, parametrized by the temperature change across each layer. This model allows the steep temperature gradient of brown dwarf atmospheres to be accurately retrieved while avoiding commonly encountered numerical artefacts. The P–T model is especially flexible in the photosphere, which can reach a few tens of bar for T-dwarfs. We demonstrate an approach to include model uncertainties in the retrieval, focusing on uncertainties introduced by finite spectral and vertical resolution in the atmospheric model used for retrieval (∼8 per cent in the present case). We validate our retrieval framework by applying it to a simulated data set and then apply it to the HST/WFC3 (Hubble Space Telescope’s Wide-Field Camera 3) spectrum of the T-dwarf 2MASS J2339+1352. We retrieve sub-solar abundances of H2O and CH4 in the object at ∼0.1 dex precision. Additionally, we constrain the temperature structure to within ∼100 K in the photosphere. Our results demonstrate the promise of high-SNR spectra to provide high-precision abundance estimates of sub-stellar objects.

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