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Infrared Telescope (infrared + telescope)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Near-infrared polarimetry and modelling of the dusty young planetary nebula IRAS 19306+1407

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2007
K. T. E. Lowe
ABSTRACT We present near-infrared polarimetric images of the dusty circumstellar envelope (CSE) of IRAS 19306+1407, acquired at the United Kingdom Infrared Telescope (UKIRT) using the UKIRT 1,5 ,m Imager Spectrometer (UIST) in conjunction with the half-waveplate module IRPOL2. We present additional 450- and 850-,m photometry data obtained with the Submillimetre Common-User Bolometer Array (SCUBA) at the James Clerk Maxwell Telescope (JCMT), as well as archived Hubble Space Telescope (HST) F606W - and F814W -filter images. The CSE structure in polarized flux at J and K bands shows an elongation north of north-east and south of south-west with two bright scattering shoulders north-west and south-east. These features are not perpendicular to each other and could signify a recent ,twist' in the outflow axis. We model the CSE using an axisymmetric light scattering (als) code to investigate the polarization produced by the CSE, and an axisymmetric radiation transport (dart) code to fit the spectral energy distribution. A good fit was achieved with the als and dart models using silicate grains, 0.1,0.4 ,m with a power-law size distribution of a,3.5, and an axisymmetric shell geometry with an equator-to-pole ratio of 7:1. The spectral type of the central star is determined to be B1i supporting previous suggestions that the object is an early planetary nebula. We have constrained the CSE and interstellar extinction as 2.0 and 4.2 mag, respectively, and have estimated a distance of 2.7 kpc. At this distance, the stellar luminosity is ,4500 L, and the mass of the CSE is ,0.2 M,. We also determine that the mass loss lasted for ,5300 yr with a mass-loss rate of ,3.4 × 10,5 M, yr,1. [source]

The possible detection of high-redshift Type II QSOs in deep fields

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2006
Avery Meiksin
ABSTRACT The colours of high-redshift Type II quasi-stellar objects (QSOs) are synthesized from observations of moderate-redshift systems. It is shown that Type II QSOs are comparable to starbursts at matching the colours of z850 -dropouts and i775 -drops in the Hubble UltraDeep Field, and more naturally account for the bluest objects detected. Type II QSOs may also account for some of the i775 -drops detected in the Great Observatories Origins Deep Survey (GOODS) fields. It is shown that by combining imaging data from the Hubble Space Telescope and the James Webb Space Telescope, it will be possible to clearly separate Type II QSOs from Type I QSOs and starbursts based on their colours. Similarly, it is shown that the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) ZYJ filters may be used to discriminate high-redshift Type II QSOs from other objects. If Type II QSOs are prevalent at high redshifts, then active galactic nuclei (AGNs) may be major contributors to the re-ionization of the intergalactic medium. [source]

Deep spectroscopy of distant 3CR radio galaxies: the data

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2000
P. N. Best
Deep long-slit spectroscopic data are presented for a sample of 14 3CR radio galaxies at redshift z,1, previously studied in detail using the Hubble Space Telescope, the Very Large Array, and the UK Infrared Telescope (UKIRT). Analysis of the [O ii] 3727 emission-line structures at ,5 Å spectral resolution is carried out to derive the kinematic properties of the emission-line gas. In line with previous lower resolution studies, a wide variety of kinematics are seen, from gas consistent with a mean rotational motion through to complex structures with velocity dispersions exceeding 1000 km s ,1. The data confirm the presence of a high-velocity gas component in 3C 265 and detached emission-line systems in 3C 356 and 3C 441, and show for the first time that the emission-line gas in the central regions of 3C 324 is composed of two kinematically distinct components. Emission-line fluxes and the colour of the continuum emission are determined down to unprecedentedly low observed wavelengths, ,<3500 Å, sufficiently short that any contribution of an evolved stellar population is negligible. An accompanying paper investigates the variation in the emission-line ratios and velocity structures within the sample, and draws conclusions as to the origin of the ionization and kinematics of these galaxies. [source]

Bright Ly, emitters at z, 9: constraints on the LF from HizELS,

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2009
D. Sobral
ABSTRACT New results are presented, as part of the Hi- z Emission Line Survey (HizELS), from the largest area survey to date (1.4 deg2) for Ly, emitters (LAEs) at z, 9. The survey, which is primarily targeting H, emitters at z < 3, uses the Wide Field CAMera on the United Kingdom Infrared Telescope and a custom narrow-band filter in the J band and reaches a Ly, luminosity limit of ,1043.8 erg s,1 over a co-moving volume of 1.12 × 106 Mpc3 at z= 8.96 ± 0.06. Only two candidates were found out of 1517 line emitters and those were rejected as LAEs after follow-up observations. The limit on the space density of bright LAEs is improved by three orders of magnitude, consistent with suppression of the bright end of the Ly, luminosity function beyond z, 6. Combined with upper limits from smaller but deeper surveys, this rules out some of the most extreme models for high-redshift LAEs. The potential contamination of future narrow-band Ly, surveys at z > 7 by Galactic brown dwarf stars is also examined, leading to the conclusion that such contamination may well be significant for searches at 7.7 < z < 8.0, 9.1 < z < 9.5 and 11.7 < z < 12.2. [source]

The short history of infrared space telescopes

ASTRONOMISCHE NACHRICHTEN, Issue 6 2009
D. Lemke
Abstract While astronomical telescopes developed rather slowly over the last four centuries, infrared telescopes made a fast career in only four decades from high mountains to aircraft, balloons and satellites. They cover the huge wavelength region from 1 to 350 , m and have uncovered the cold and dust hidden universe. While until today all infrared space telescopes had diameters of <1 m, cooled infrared observatories with 3.5 to 6.5m mirrors will be sent into heliocentric orbits at L2 within the next few years (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]