Mid - Infrared Imaging and Modelling of the Dust Shell around Post - AGB star HD 187885 ( IRAS 19500 - 1709 )
نویسنده
چکیده
We present 10 and 20 μm images of IRAS 19500-1709 taken with the mid-infrared camera, OSCIR, mounted on the Gemini North Telescope. An extended circumstellar envelope is detected, with the N band image indicating an elongation in a NE-SW direction. We use a dust radiation transport code to fit the spectral energy distribution from UV to sub-mm wavelengths, with a detached dust shell model. A good fit is achieved using dust composed of amorphous carbon, silicon carbide and magnesium sulphide. We derive estimates for the inner and outer radius, density and mass of the dust in the shell. The inner radius is not resolved in our OSCIR imaging, giving an upper limit of 0.4 arcsec. With this constraint, we conclude that IRAS 19500-1709 must be at least 4 kpc away in order to have the minimum luminosity consistent with a post-AGB status.
منابع مشابه
The Dying-wind around Hd 56126, a Post-agb Carbon Star
We have used the Keck I telescope to resolve at mid-infrared wavelengths the dust emission from HD 56126 (IRAS 07134+1005), a post-Asymptotic Giant Branch carbon star with a detached dust shell. The gross morphology of the image can be explained by a strong wind which started to die about 1500 years ago. If the star had an effective temperature, T∗, near 2600 K when it was losing ∼3 × 10 M⊙ yr ...
متن کاملHigh-Resolution Imaging of Objects in the Post-AGB to Planetary Nebula Transition
We have obtained high-resolution images of two carbon-rich objects that are undergoing the transition from post-AGB star to planetary nebula: IRAS 21282+5050 (hereafter IRAS 21282), a young planetary nebula, and AFGL 3068, a post-AGB star with a high mass-loss rate. Detailed structure is seen in IRAS 21282. A torus of dust, with its polar axis in the N-S direction, surrounds the central star, i...
متن کاملMid-infrared interferometry on spectral lines: II. Continuum (dust) emission around IRC +10216 and VY CMa
The U. C. Berkeley Infrared Spatial Interferometer has measured the mid-infrared visibilities of the carbon star IRC +10216 and the red supergiant VY CMa. The dust shells around these sources have been previously shown to be time-variable, and these new data are used to probe the evolution of the dust shells on a decade time-scale, complementing contemporaneous studies at other wavelengths. Sel...
متن کاملTo appear in the Astrophysical Journal Discovery of an Extended Dust Emission around IRAS 18576+0341 (AFGL 2298) at 10.3 and 18.0 microns: a New Luminous Blue Variable Candidate?
We report detection of an extended mid-infrared emission from IRAS 18576+0341 (AFGL 2298). The object shows a dusty circumstellar shell that has diameter of >∼ 7 ′′ at 10.3 and 18.0 μm. The dust nebula shows two emission peaks concentrically elongated and symmetrically oriented on the opposite sides of the third, central peak, which appears to be the central star of the system. The observed mid...
متن کاملar X iv : a st ro - p h / 04 02 03 7 v 1 2 F eb 2 00 4 PAHs and crystalline silicates in the bipolar post - AGB star IRAS 16279 − 4757 12
IRAS 16279−4757 belongs to a group of post-AGB stars showing both PAH bands and crystalline silicates. We present mid-infrared images, that resolve the object for the first time. The morphology is similar to that of the 'Red Rectangle' (HD 44179), the prototype object with PAHs and crystalline sili-cates. A two-component model and images suggest a dense oxygen-rich torus, an inner, low-density ...
متن کامل