2007A&A...466.1099O


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.05CEST07:20:48

2007A&A...466.1099O - Astronomy and Astrophysics, volume 466, 1099-1110 (2007/5-2)

Temporal variations of the outer atmosphere and the dust shell of the carbon-rich Mira variable V Ophiuchi probed with VLTI/MIDI.

OHNAKA K., DRIEBE T., WEIGELT G. and WITTKOWSKI M.

Abstract (from CDS):

We present the first multi-epoch N-band spectro-interferometric observations of the carbon-rich Mira variable V Oph using MIDI at the ESO's Very Large Telescope Interferometer. Our aim is to study temporal variations of physical properties of the outer atmosphere and the circumstellar dust shell based on spectrally-dispersed N-band visibilities over the C2H2 (+HCN) features and the dust emission. Our MIDI observations were carried out at three different phases 0.18, 0.49, and 0.65, with three different baselines (projected baseline lengths of 42-124m) using four 8.2m Unit Telescopes (UT2-UT4, UT1-UT4, and UT2-UT3 baseline configurations). The wavelength dependence of the uniform-disk diameters obtained at all epochs is characterized by a roughly constant region between 8 and 10µm with a slight dip centered at ∼9.5µm and a gradual increase longward of 10µm. These N-band angular sizes are significantly larger than the estimated photospheric size of V Oph. The angular sizes observed at different epochs reveal that the object appears smaller at phase 0.49 (minimum light) with uniform-disk diameters of ∼5-12mas than at phases 0.18 (∼12-20mas) and 0.65 (∼9-15mas). We interpret these results with a model consisting of optically thick C2H2 layers and an optically thin dust shell. Our modeling suggests that the C2H2 layers around V Oph are more extended (∼1.7-1.8R*) at phases 0.18 and 0.65 than at phase 0.49 (∼1.4R*) and that the C2H2 column densities appear to be the smallest at phase 0.49. We also find that the dust shell consists of amorphous carbon and SiC with an inner radius of ∼2.5R*, and the total optical depths of τV≃0.6-0.9 (τ11.3µm≃0.003 and 0.004 for amorphous carbon and SiC, respectively) found at phases 0.18 and 0.65 are higher than the value obtained at phase 0.49, τV≃0.3 (τ11.3µm≃0.001 and 0.002 for amorphous carbon and SiC, respectively). Our MIDI observations and modeling indicate that carbon-rich Miras also have extended layers of polyatomic molecules as previously confirmed in oxygen-rich Miras. The temporal variation of the N-band angular size is largely governed by the variations of the opacity and the geometrical extension of the C2H2 layers and the dust shell, and consequently, this masks the size variation of the photosphere. Also, the observed weakness of the mid-infrared C2H2 absorption in carbon-rich Miras can be explained by the emission from the extended C2H2 layers and the dust shell.

Abstract Copyright:

Journal keyword(s): infrared: stars - techniques: interferometric - stars: circumstellar matter - stars: carbon - stars: AGB and post-AGB - stars: individual: V Oph

VizieR on-line data: <Available at CDS (J/A+A/466/1099): table4.dat>

Simbad objects: 25

goto Full paper

goto View the reference in ADS

Number of rows : 25

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 V* R Scl C* 01 26 58.0946233986 -32 32 35.437732667 17.26 9.59 5.72 3.69 2.30 C-N5+ 297 0
2 * omi Cet Mi* 02 19 20.79210 -02 58 39.4956   7.63 6.53 5.03   M5-9IIIe+DA 1434 0
3 * phi02 Ori PM* 05 36 54.3881859 +09 17 26.409553 5.70 5.04 4.09 3.33 2.78 G9.5IIIbFe-2.5 337 0
4 V* R Leo Mi* 09 47 33.4839808805 +11 25 43.823283729 9.22 8.94 7.53 3.39 0.12 M7-9e 870 1
5 HD 120404 * 13 51 47.4342248812 -69 24 04.515687153   7.459 5.727     K5/M0III 22 0
6 * bet Cen bC* 14 03 49.40535 -60 22 22.9266   0.38 0.60     B1III 338 0
7 HD 142804 * 15 57 05.2072580095 -16 02 03.884605552   8.316 6.542     M1.5III 41 0
8 V* V Oph C* 16 26 43.7071803249 -12 25 35.815297379   12.91 7.30     C-N:4 129 0
9 HD 150052 V* 16 38 47.7271198147 -08 37 06.981983370   8.27 6.45     K4III 11 0
10 * 27 Sco * 16 57 11.1750379327 -33 15 34.174129724   7.11 5.49     K5III 23 0
11 V* V1071 Sco LP* 16 57 50.2212714244 -39 06 56.612452377   8.37 6.58     M1III 16 0
12 * 43 Oph * 17 23 21.5908499959 -28 08 34.195626020   6.844 5.288     K4/5III 28 0
13 HD 160668 * 17 42 51.0974966369 -36 56 44.020326314   7.073 5.520     K5III 16 0
14 * gam02 Sgr PM* 18 05 48.4880988 -30 25 26.723458 4.77 4.00 2.99 2.26 1.75 K0+III 128 0
15 * eta Ser PM* 18 21 18.6005560 -02 53 55.776595 4.84 4.19 3.25 2.55 2.05 K0III-IV 351 0
16 * lam Sgr PM* 18 27 58.2407185 -25 25 18.114589 4.75 3.85 2.81 2.06 1.50 K1IIIb 259 0
17 * zet Tel PM* 18 28 49.8597995 -49 04 14.112225   5.15 4.13     K1III-IV 44 0
18 * bet CrA * 19 10 01.7558032 -39 20 26.864359   5.281 4.095     K0II/IIICNIb 50 0
19 * chi Cyg S* 19 50 33.9243904 +32 54 50.609683 7.02 6.06 4.24 1.81 -0.01 S6-9/1-2e 663 0
20 * bet Aql PM* 19 55 18.7925630 +06 24 24.342501 5.040 4.560 3.710 3.05 2.56 G8IV 514 0
21 V* Z Cyg Mi* 20 01 27.5084697298 +50 02 32.631014105   11.12 7.10     M5.5-6.5e 155 0
22 V* U Cyg C* 20 19 36.5944622319 +47 53 39.085332215   11.85 5.90     C9,2e 223 0
23 V* V Cyg C* 20 41 18.2688237607 +48 08 28.886946369   14.05 7.70     C7,4eJ 290 0
24 V* S Cep C* 21 35 12.8240104870 +78 37 28.201592479   12.13 7.40     C7,3e 245 0
25 V* RZ Peg Mi* 22 05 52.9711216769 +33 30 24.810194832   11.40 7.60     SC5-9/9-e 145 0

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2007A&A...466.1099O and select 'bookmark this link' or equivalent in the popup menu


2020.07.05-07:20:48

© Université de Strasbourg/CNRS

    • Contact