2014A&A...561A..47O


Query : 2014A&A...561A..47O

2014A&A...561A..47O - Astronomy and Astrophysics, volume 561A, 47-47 (2014/1-1)

High spectral resolution spectroscopy of the SiO fundamental lines in red giants and red supergiants with VLT/VISIR.

OHNAKA K.

Abstract (from CDS):

The mass-loss mechanism in red giants and red supergiants is not yet understood well. The SiO fundamental lines near 8 µm are potentially useful for probing the outer atmosphere, which is essential for clarifying the mass-loss mechanism. However, these lines have been little explored until now. We present high spectral resolution spectroscopic observations of the SiO fundamental lines near 8.1 µm in 16 bright red giants and red supergiants. Our sample consists of seven normal (i.e., non-Mira) K-M giants (from K1.5 to M6.5), three Mira stars, three optically bright red supergiants, two dusty red supergiants, and the enigmatic object GCIRS3 near the Galactic center. Our program stars were observed between 8.088 µm and 8.112 µm with a spectral resolution of 30000 using VLT/VISIR. We detected SiO fundamental lines in all of our program stars except for GCIRS3. The SiO lines in normal K and M giants as well as optically bright (i.e., not dusty) red supergiants do not show P-Cyg profiles or blueshifts, which means the absence of systematic outflows in the SiO line forming region. We detected P-Cyg profiles in the SiO lines in the dusty red supergiants VY CMa and VX Sgr, with the latter object being a new detection. These SiO lines originate in the outflowing gas with the thermal dust continuum emission seen as the background. The outflow velocities of the SiO line forming region in VY CMa and VX Sgr are estimated to be 27 km/s and 17 km/s, respectively. We derived basic stellar parameters (effective temperature, surface gravity, luminosity, and mass) for the normal K-M giants and optically bright red supergiants in our sample and compared the observed VISIR spectra with synthetic spectra predicted from MARCS photospheric models. Most of the SiO lines observed in the program stars warmer than ∼3400 K are reasonably reproduced by the MARCS models, which allowed us to estimate the silicon abundance as well as the 28Si/29Si and 28Si/30Si ratios. However, we detected possible absorption excess in some SiO lines. Moreover, the SiO lines in the cooler red giants and red supergiant cannot be explained by the MARCS models at all, even if the dust emission is taken into account. This disagreement may be a signature of the dense, extended molecular outer atmosphere.

Abstract Copyright:

Journal keyword(s): infrared: stars - techniques: spectroscopic - stars: AGB and post-AGB - stars: late-type - stars: atmospheres - supergiants

VizieR on-line data: <Available at CDS (J/A+A/561/A47): stars.dat sp/*>

Simbad objects: 27

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Number of rows : 27
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 * omi Cet Mi* 02 19 20.79210 -02 58 39.4956   7.63 6.53 5.03   M5-9IIIe+DA 1488 0
2 * alf Ori s*r 05 55 10.30536 +07 24 25.4304 4.38 2.27 0.42 -1.17 -2.45 M1-M2Ia-Iab 1568 0
3 * alf Car * 06 23 57.10988 -52 41 44.3810 -0.49 -0.59 -0.74 -0.96 -1.13 A9II 436 0
4 * L02 Pup AB* 07 13 32.3185436236 -44 38 22.951891964 7.90 6.66 5.10 2.49 0.07 M5IIIe 207 0
5 V* VY CMa s*r 07 22 58.32877 -25 46 03.2355 12.01 10.19 7.95     M5Iae 1055 0
6 * alf CMi SB* 07 39 18.11950 +05 13 29.9552 0.82 0.79 0.37 -0.05 -0.28 F5IV-V+DQZ 1825 0
7 V* R Leo Mi* 09 47 33.4839808805 +11 25 43.823283729 9.22 8.94 7.53 3.39 0.12 M7-9e 891 1
8 IRC +10216 C* 09 47 57.40632 +13 16 43.5648     10.96     C9,5e 2246 0
9 * eps Mus LP* 12 17 34.2771607 -67 57 38.648630 7.27 5.60 4.02 2.12 0.36 M4III 71 0
10 * gam Cru PM* 12 31 09.95961 -57 06 47.5684 5.01 3.23 1.64 -0.02 -1.44 M3.5III 269 0
11 V* R Hya Mi* 13 29 42.7818674 -23 16 52.774679 7.26 6.58 4.97 2.27 -0.15 M6-9e 473 0
12 V* W Hya Mi* 13 49 02.0018313132 -28 22 03.532006894   8.97 7.70     M7.5-9e 623 0
13 * g Cen LP* 13 49 26.7217509 -34 27 02.792908 7.15 5.69 4.19 2.06 0.19 M5-III: 138 0
14 * tet Aps LP* 14 05 19.8778357 -76 47 48.320384 8.10 7.05 5.50     M6.5III: 117 0
15 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2232 0
16 * alf Cen A SB* 14 39 36.49400 -60 50 02.3737 0.96 0.72 0.01     G2V 1208 0
17 * sig Lib LP* 15 04 04.2160765 -25 16 55.060636 6.86 4.91 3.21 1.60 0.33 M2.5III 181 0
18 * alf Sco s*r 16 29 24.45970 -26 25 55.2094 4.08 2.75 0.91 -0.64 -1.87 M1.5Iab+B2Vn 727 0
19 * alf Her A LP* 17 14 38.852741 +14 23 25.33577   4.67 3.33     M5Ib-II 435 0
20 * alf Her ** 17 14 38.85818 +14 23 25.2262   4.51 3.06     M5Ib-II+G5III+F2V: 194 0
21 * alf Her B SB* 17 14 39.1724224693 +14 23 24.008038035   6.030 5.322     G5III+F2V: 133 1
22 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13094 0
23 GCIRS 3 * 17 45 39.80 -29 00 23.9           ~ 143 0
24 V* VX Sgr s*r 18 08 04.0442790744 -22 13 26.600899044 11.72 9.41 6.52 3.90 2.11 M8.5Ia 579 0
25 V* R Aql OH* 19 06 22.2510922392 +08 13 48.012661776 8.06 7.69 6.09     M6.5-9e 548 0
26 * alf Aql dS* 19 50 46.99855 +08 52 05.9563 1.07 0.98 0.76 0.62 0.49 A7Vn 848 0
27 V* R Cas Mi* 23 58 24.8682785040 +51 23 19.713029388 6.71 6.63 4.80     M6.5-9e 691 0

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2022.08.15-15:04:28

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