2012A&A...544L...5P


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.07CET04:39:01

2012A&A...544L...5P - Astronomy and Astrophysics, volume 544, L5-5 (2012/8-1)

Detection of an asymmetry in the envelope of the carbon Mira R Fornacis using VLTI/MIDI.

PALADINI C., SACUTO S., KLOTZ D., OHNAKA K., WITTKOWSKI M., NOWOTNY W., JORISSEN A. and HRON J.

Abstract (from CDS):

We present a study of the envelope morphology of the carbon Mira R For with VLTI/MIDI. This object is one of the few asymptotic giant branch (AGB) stars that underwent a dust-obscuration event. The cause of such events is still a matter of discussion. Several symmetric and asymmetric scenarios have been suggested in the literature. Mid-infrared interferometric observations were obtained separated by two years. The observations probe different depths of the atmosphere and cover different pulsation phases. The visibilities and the differential phases were interpreted using GEM-FIND, a tool for fitting spectrally dispersed interferometric observations with the help of wavelength-dependent geometric models. We report the detection of an asymmetric structure revealed through the MIDI differential phase. This asymmetry is observed at the same baseline and position angle two years later. The observations are best simulated with a model that includes a uniform-disc plus a Gaussian envelope plus a point-source. The geometric model can reproduce both the visibilities and the differential phase signatures. Our MIDI data favour explanations of the R For obscuration event that are based on an asymmetric geometry. We clearly detect a photocentre shift between the star and the strongly resolved dust component. This might be caused by a dust clump or a substellar companion. However, the available observations do not allow us to distinguish between the two options. The finding has strong implications for future studies of the geometry of the envelope of AGB stars: if this is a binary, are all AGB stars that show an obscuration event binaries as well? Or are we looking at asymmetric mass-loss processes (i.e. dusty clumps) in the inner part of a carbon-rich Mira?

Abstract Copyright:

Journal keyword(s): stars: AGB and post-AGB - stars: mass-loss - stars: late-type - stars: carbon - techniques: high angular resolution - techniques: interferometric

Simbad objects: 11

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Number of rows : 11

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 * 30 Psc LP? 00 01 57.6152259896 -06 00 50.668429443 7.88 6.04 4.41 2.85 1.44 M3III 128 0
2 * alf Ari PM* 02 07 10.40570 +23 27 44.7032 4.29 3.17 2.01 1.15 0.54 K2-IIIbCa-1 601 1
3 V* R For C* 02 29 15.3081251463 -26 05 55.647016467   12.94 7.50     C4,3e 177 0
4 * tau04 Eri LP* 03 19 31.0022373 -21 45 28.304953 7.13 5.32 3.70 2.12 0.66 M3III-IIIaCa-1 102 0
5 * gam Eri LP? 03 58 01.7669489 -13 30 30.669770 6.52 4.54 2.94 1.68 0.68 M0III-IIIb 168 0
6 * alf CMa SB* 06 45 08.91728 -16 42 58.0171 -1.51 -1.46 -1.46 -1.46 -1.43 A1V+DA 1376 0
7 V* BM Gem C* 07 20 59.0073994507 +24 59 58.090785507     11.50     C-J5- 137 1
8 IRC +10216 C* 09 47 57.406 +13 16 43.56     10.96     C9,5e 2109 0
9 V* RW LMi C* 10 16 02.2834693816 +30 34 18.977096332       15.27   C4,3e 377 0
10 IRAS 18006-3213 OH* 18 03 52.8258880496 -32 12 59.385021229       12.24 9.71 ~ 34 0
11 V* RY Sgr RC* 19 16 32.7669543079 -33 31 20.337025534 6.20 6.27 6.25     Cpec 353 0

    Equat.    Gal    SGal    Ecl

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2019.12.07-04:39:01

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