scholarly journals High Angular Resolution Observations of Her 36

1994 ◽  
Vol 158 ◽  
pp. 364-366
Author(s):  
B. Stecklum ◽  
R.R. Howell ◽  
A. Eckart ◽  
A. Richichi
Keyword(s):  
Near Infrared ◽  
Angular Resolution ◽  
Speckle Interferometry ◽  
High Angular Resolution ◽  
Speckle Image ◽  
Lunar Occultation ◽  
L Band ◽  
Occultation Data

The star Herschel 36 (Her 36) which ionizes most of the Hourglass nebula has been observed during a lunar occultation as well as by speckle interferometry in the near infrared (NIR). From the lunar occultation data the strip brightness profile has been extracted which shows that in the L′ band Her 36 is extended with a FWHM of 0.45″. Subsequent speckle interferometry revealed 11 sources in a 6′ × 6′ area at a level of 0.15″ resolution. From the comparison of the brightness profile obtained by the occultation and the strip brightness profile synthesized from the speckle image, we conclude that Her 36 is surrounded by a very young infrared cluster.

scholarly journals Infrared speckle interferometry of OH-stars

1987 ◽  
Vol 122 ◽  
pp. 245-246
Author(s):  
Jessica M. Chapman ◽  
R.D. Wolstencroft
Keyword(s):  
Spatial Distribution ◽  
Near Infrared ◽  
Angular Resolution ◽  
Speckle Interferometry ◽  
Physical Structure ◽  
High Mass ◽  
High Angular Resolution ◽  
Circumstellar Envelopes ◽  
Infrared Measurements ◽  
High Mass Loss

We have begun a co-ordinated programme of high angular-resolution radio and infrared measurements to study the physical structure of the circumstellar envelopes surrounding high mass-loss OH-stars. Here we give near-infrared (NIR) angular diameters for 5 stars. For each of these stars the spatial distribution of the OH maser emission at 1612 MHz or 1665 MHz has been previously mapped.

scholarly journals Influence of the input-stage architecture on the in-laboratory test of a mid-infrared interferometer: application to the ALOHA up-conversion interferometer in the L band

2020 ◽  
Vol 501 (1) ◽  
pp. 531-540
Author(s):  
Julie Magri ◽  
Lucien Lehmann ◽  
Ludovic Grossard ◽  
Laurent Delage ◽  
François Reynaud ◽  
...  
Keyword(s):  
Laboratory Test ◽  
Near Infrared ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
High Flux ◽  
Hybrid Analysis ◽  
Mid Infrared ◽  
Input Stage ◽  
L Band ◽  
Set Up

ABSTRACT In the framework of the Astronomical Light Optical Hybrid Analysis (ALOHA) laboratory mid-infrared (MIR) up-conversion fibred interferometer in the L band, we report on the influence of the input-stage architecture. Using an amplitude division set-up in the visible or near-infrared is a straightforward choice in most cases. In the MIR context, the results are slightly different and we show that a wavefront division set-up is needed. These in-laboratory principle experiments allow us to measure a reliable 88 per cent instrumental contrast with high flux and to obtain fringes from faint sources at 3.5 μm with a spectral bandwith of 37 nm converted to 817 nm. An equivalent limiting L-band magnitude around 3.9, equivalent to 3.0 fW nm−1, could be demonstrated on 1 m class telescopes. This opens the possibility of planning future on-sky tests at the Center for High Angular Resolution Astronomy (CHARA) array and of predicting the performance attained.

Zooming into the complex dusty envelopes of C-rich AGB stars

2018 ◽  
Vol 14 (S343) ◽  
pp. 456-457
Author(s):  
Foteini Lykou ◽  
Josef Hron ◽  
Daniela Klotz
Keyword(s):  
Temperature Distribution ◽  
Near Infrared ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
Dust Formation ◽  
Agb Stars ◽  
Circumstellar Envelopes ◽  
Recent Advances ◽  
Multi Wavelength

AbstractRecent advances in high-angular resolution instruments (VLT and VLTI, ALMA) have enabled us to delve deep into the circumstellar envelopes of AGB stars from the optical to the sub-mm wavelengths, thus allowing us to study in detail the gas and dust formation zones (e.g., their geometry, chemistry and kinematics). This work focuses on four (4) C-rich AGB stars observed with a high-angular resolution technique in the near-infrared: a multi-wavelength tomographic study of the dusty layers of the circumstellar envelopes of these C-rich stars, i.e. the variations in the morphology and temperature distribution.

scholarly journals High gas-to-dust size ratio indicating efficient radial drift in the mm-faint CX Tauri disk

2019 ◽  
Vol 626 ◽  
pp. L2 ◽  
Author(s):  
S. Facchini ◽  
E. F. van Dishoeck ◽  
C. F. Manara ◽  
M. Tazzari ◽  
L. Maud ◽  
...  
Keyword(s):  
Near Infrared ◽  
Angular Resolution ◽  
Spectral Energy Distribution ◽  
Theoretical Models ◽  
Intensity Profile ◽  
Continuum Emission ◽  
Spectral Energy ◽  
High Angular Resolution ◽  
Sharp Drop ◽  
Large Program

The large majority of protoplanetary disks have very compact continuum emission (≲15 AU) at millimeter wavelengths. However, high angular resolution observations that resolve these small disks are still lacking, due to their intrinsically fainter emission compared with large bright disks. In this Letter we present 1.3 mm ALMA data of the faint disk (∼10 mJy) orbiting the TTauri star CX Tau at a resolution of ∼40 mas, ∼5 AU in diameter. The millimeter dust disk is compact, with a 68% enclosing flux radius of 14 AU, and the intensity profile exhibits a sharp drop between 10 and 20 AU, and a shallow tail between 20 and 40 AU. No clear signatures of substructure in the dust continuum are observed, down to the same sensitivity level of the DSHARP large program. However, the angular resolution does not allow us to detect substructures on the scale of the disk aspect ratio in the inner regions. The radial intensity profile closely resembles the inner regions of more extended disks imaged at the same resolution in DSHARP, but with no rings present in the outer disk. No inner cavity is detected, even though the disk has been classified as a transition disk from the spectral energy distribution in the near-infrared. The emission of 12CO is much more extended, with a 68% enclosing flux radius of 75 AU. The large difference of the millimeter dust and gas extents (> 5) strongly points to radial drift, and closely matches the predictions of theoretical models.

scholarly journals Mira’s Companion(s)

1992 ◽  
Vol 135 ◽  
pp. 558-560
Author(s):  
M. Karovska
Keyword(s):  
Angular Resolution ◽  
Speckle Interferometry ◽  
High Angular Resolution ◽  
Third Body ◽  
Show Evidence ◽  
Visual Observations

AbstractRecent high–angular resolution speckle interferometry measurements of the positions of Mira’s companion are presented in context of the previous visual observations. The analysis of the separation measurements since 1923 show evidence for possible third body in the system.

scholarly journals The Calibration of Interferometrically Determined Properties of Binary Stars

1985 ◽  
Vol 111 ◽  
pp. 97-119
Author(s):  
Harold A. McAlister
Keyword(s):  
Binary Stars ◽  
Angular Resolution ◽  
Binary Star ◽  
Angular Separation ◽  
Speckle Interferometry ◽  
Close Binaries ◽  
High Angular Resolution ◽  
Fundamental Field ◽  
Enhanced Resolution ◽  
Stellar Masses

With the advent of speckle interferometry, high angular resolution has begun to play a routine role in the study of binary stars. Speckle and other interferometric techniques not only bring enhanced resolution to this classic and fundamental field but provide an equally important gain in observational accuracy. These methods also offer the potential for performing accurate differential photometry for binary stars of very small angular separation. This paper reviews the achievements of modern interferometric techniques in measuring stellar masses and luminosities and discusses the special calibration problems encountered in binary star interferometry. The future possibilities for very high angular resolution studies of close binaries are also described.

Near Infrared High Angular Resolution Observations of Stars and Circumstellar Regions by the Technique of Lunar Occultations

1994 ◽  
Vol 158 ◽  
pp. 376-378
Author(s):  
T. Chandrasekhar ◽  
N. M. Ashok ◽  
Sam Ragland
Keyword(s):  
High Speed ◽  
Near Infrared ◽  
Angular Resolution ◽  
Infrared Region ◽  
High Angular Resolution ◽  
Filter Bandwidth ◽  
One Dimensional ◽  
Near Infrared Region ◽  
System Frequency ◽  
Source Structure

A program of High Angular Resolution observations of stars and their circumstellar regions using the technique of lunar occultations has been initiated at the 1.2 m telescope at Gurushikhar (24°39′ N, 72°47′ E), India. A liquid nitrogen cooled InSb detector based high speed Infrared photometer with millisecond data acquisition capabilities has been developed for the near Infrared region (1–5 μm) and eight occultations have been successfully observed in the K band (2.2 μm). The sources are (IRC No. -10578, +10013, +20034, +30094, +20190, +20200, +20073 and +00198. The diffraction pattern is clearly seen in all the observations. A convolution analysis involving the system frequency response, filter bandwidth and one dimensional source structure has been carried out to fit the data. System capability has been determined to be ~ 6 milliarcseconds.

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