2005A&A...435..563C


Query : 2005A&A...435..563C

2005A&A...435..563C - Astronomy and Astrophysics, volume 435, 563-574 (2005/5-4)

The mid-IR spatially resolved environment of OH 26.5+0.6 at maximum luminosity.

CHESNEAU O., VERHOELST T., LOPEZ B., WATERS L.B.F.M., LEINERT C., JAFFE W., KOEHLER R., DE KOTER A. and DIJKSTRA C.

Abstract (from CDS):

We present observations of the famous OH/IR star OH 26.5+0.6 obtained using the Mid-Infrared Interferometric Instrument MIDI at the European Southern Observatory (ESO) Very Large Telescope Interferometer VLTI. Emission of the dusty envelope, spectrally dispersed at a resolution of 30 from 8µm to 13.5µm, appears resolved by a single dish UT telescope. In particular the angular diameter increases strongly within the silicate absorption band. Moreover an acquisition image taken at 8.7µm exhibits, after deconvolution, a strong asymmetry. The axis ratio is 0.75±0.07 with the FWHM of the major and minor axis which are 286 mas and 214 mas respectively. The measured PA angle, 95° ±6°, is reminiscent of the asymmetry in the OH maser emission detected at 1612MHz. In interferometric mode the UT1-UT3 102m baseline was employed to detect the presence of the star. No fringes were found with a detection threshold estimated to be about 1% of the total flux of the source, i.e. 5-8Jy. These observations were carried out during the maximum luminosity phase of the star, when the dust shell is more diluted and therefore the chance to detect the central source maximized. We modeled the dusty environment based on the work of Justtanont et al. (1996ApJ...456..337J). In particular, the failure to detect fringes provides strong constraints on the opacities in the inner regions of the dust shell or in the close vicinity of the star.

Abstract Copyright:

Journal keyword(s): radiative transfer - techniques: interferometric - stars: AGB and post-AGB - stars: circumstellar matter - stars: individual: OH 26.5+0.6

Simbad objects: 9

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Number of rows : 9
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 M 77 GiP 02 42 40.771 -00 00 47.84 9.70 9.61 8.87 10.1 9.9 ~ 4236 2
2 IRC +10216 C* 09 47 57.40632 +13 16 43.5648     10.96     C9,5e 2205 0
3 * eta Car Em* 10 45 03.545808 -59 41 03.95124 6.37 7.03 6.48 4.90 4.41 OBepec 2284 0
4 HD 100546 Be* 11 33 25.4404858122 -70 11 41.239343121   6.71 6.30   6.64 A0VaekB8_lB 688 1
5 RAFGL 6815S pA* 17 18 19.8316623567 -32 27 21.376880888           G2I 148 0
6 * del Sgr * 18 20 59.6435424 -29 49 41.165919   4.069 2.668     K2.5IIIaCN0.5 165 0
7 OH 26.5 +0.6 OH* 18 37 32.50920 -05 23 59.1936           O-rich 286 0
8 * tau Sgr PM* 19 06 56.4052936935 -27 40 13.609432896 5.65 4.51 3.31 2.44 1.85 K1.5IIIb 149 0
9 V* V1610 Cyg pA* 21 02 18.27 +36 41 37.0           F5Iae 843 1

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2021.09.17-18:01:48

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