<=== observer ===>
"KVDHUCHT",\
"van der Hucht, K.A.",\
"",\
"SRON Utrecht",\
"Sorbonnelaan 2",\
"",\
"3584 CA",\
"Utrecht",\
"The Netherlands",\
"31 30 535729",\
"31 30 540860",\
"KarelH@sron.ruu.nl (INTERNET)"
<=== proposal ===>
"WRSTARS", 1, 3,\
{"early-type stars",\
"stellar winds",\
"abundances",\
"dust properties"},\
{"P.M. Williams",\
"ROE",\
"UK"}
<=== title ===>
Winds and Dust Formation by Wolf-Rayet Stars
<=== abstract ===>
SCIENTIFIC ABSTRACT
Observations of Population I Wolf-Rayet stars with the ISO-SWS in the
grating mode are proposed in order to determine wind chemical
abundances, wind velocities, free-free radiation by winds, mass loss
rates, and, of late WC types, continuous and episodic dust formation
rates and dust abundances.
The selected priority-1 targets are the IR-brightest dust-free objects
among the known galactic WR stars, justifying maximum use of the SWS
grating-mode capacities.
This proposal has been coordinated with LWS and PHOT.
Abundances: Current WR star abundance ratio determinations, based on
model atmospheres and mainly for He, N and C, are severely model
dependent.
Determinations of the abundances of nucleosynthesis products O, Ne, Mg,
S and Ar, which have forbidden transitions in the SWS wavelength range,
will provide a direct test of evolutionary studies and of interior model
abundance predictions by, e.g., Maeder and by Langer. Presently the
(ground-based and IRAS) observed Ne abundance in the WC star gamma
Velorum (WR11) is in conflict with interior models. ISO-SWS observations
of WR stars will be crucial to solve this problem.
Winds and mass loss: Different observational methods yield different
terminal wind velocity values per star, due to the stratification of
these velocities. Measurements in the constant velocity regime are
essential. IR forbidden lines, formed in the constant wind velocity
regime, have to date been measured for one WR star only: WR11. SWS will
change that.
Mass loss rates: Current mass loss rate determinations for WR stars,
based on ground-based IR and radio free-free radiation measurents (for
density) and UV P-Cygni profiles (for velocity), range from
5x10^-6 to 10^-4 M_sun/yr, with accuracies of at
best a factor of 2. Yet, even the lower estimates of WR mass loss rates
indicate a wind momentum problem: the average WR star radiation field is
not strong enough to drive the observed mass loss rates by radiation
pressure alone. The assessment of more accurate mass loss rates with SWS
data will allow a better choice between possible accelleration
mechanisms adding to the driving of the observed mass loss rates.
Energy distributions: Discrepancies exists for many WR stars between the
IR and radio spectral indices. Where an ideal wind should display a
spectral index of 0.6 for radiation originating in the constant
velocity regime, WR stars show consistently larger values, at least
between 2mu and 6cm. This may be due to their velocity fields and to
recombination in the outer layers, and/or to the presence of non-thermal
radiation sources in the winds. SWS spectra will be allow the separation
of emission lines and continuum in order to assess the real IR
continuum.
Dust formation and episodic dust formation: The cause of dust formation
in the hot winds of late WC-type stars, i.e., in a very hostile
environment for dust formation, is not yet known. SWS spectra will
reveal dust energy distributions and dust features with unprecedented
accuracy. A growing number of long-period eccentric WC+O binaries shows
episodic dust formation. SWS observations of the objects WR48a, WR98a,
WR137 and WR140 will giving clues to the chemistry of very fresh dust.
OBSERVATION SUMMARY
We plan to obtain full SWS scans with AOT SWS06 for four WR stars and
full SWS scans with AOT SWS01 for ten WR stars.
Instrument: ISO-SWS grating mode
AOT SWS06: Grating Scan
AOT SWS01: Low Resolution Full Grating Scan
Total TDT: 13.9 hours in case of Orion hole
Total TDT: 13.7 hours in case of Galactic Center hole
Coordination: 9 objects with LWS, 7 objects with PHOT
Priority 1: total TDT = 5.9 hr (Orion hole), or 5.9 hr (Galactic Center hole)
Priority 2: total TDT = 4.3 hr (Orion hole), or 5.7 hr (Galactic Center hole)
Priority 3: total TDT = 3.7 hr (Orion hole), or 2.1 hr (Galactic Center hole)
<=== scientific_justification ===>
Time distribution for Autumn Launch targets:
Team top 43% second 31% last 26%
SWS 21326 15448 13146
Time distribution for Spring Launch targets:
Team top 43% second 42% last 15%
SWS 21326 20477 7512
Table 1. Cross-references source names:
-----------------------------------------------------------------------
WR6
WR11 HD 68273 Gamma2 Velorum IRAS 08079-4711
WR48a Danks 1
WR70 HD 137603
WR78 HD 151932
WR98a IRAS 17380-3031
WR104 Ve2-45 IRAS 17590-2337
WR112 GL 2104 IRAS 18136-1347
WR118
WR135 HD 192103
WR136 HD 192163
WR137 HD 192641
WR140 HD 193793 IRAS 20187+4341
WR147 AS431 IRAS 20349+4010
-----------------------------------------------------------------------
Table 2. Positions and offsets
-----------------------------------------------------------------------
WR RA Dec precision offset diameter reference pos.
1950 (",") (",") (")
6 06 52 08.1 -23 51 52 1,1 0.0 1
11 08 07 59.5 -47 11 18 1,1 0,0 1
48a 13 09 27 -62 27 01 1,1 0,0 1
70 15 25 44.9 -58 24 33 1,1 0,0 1
78 16 48 48.4 -41 46 17 1,1 0,0 1
98a 17 38 00.0 -30 31 02 1,1 0,0 1
104 17 59 01.1 -23 37 44 1,1 0,0 1
112 18 13 36.8 -18 59 47 1,1 0,0 1
118 18 28 56.8 -10 01 27 1,1 0,0 1
135 20 10 00.8 +36 02 49 1,1 0,0 1
136 20 10 17.1 +38 12 15 1,1 0,0 1
137 20 12 39.4 +36 30 28 1,1 0,0 1
140 20 18 46.7 +43 41 43 1,1 0,0 1
147 20 34 53.8 +40 10 38 1,1 0,0 1
-----------------------------------------------------------------------
References for position and accuracy
Reference 1: van der Hucht, K.A., Conti, P.S., Lunstrom, I., Stenholm,
B.: 1981, Space Sci. Rev. 28, 227.
Table 3. Detailed use of AOT's and integration times (S/N=20 requested)
calculated with SOTE program version 5.10 of December 13 1993
===========================================================================
WR ion range lambda_r AOT fwhm S/N int-time OTT-cum
(mu) (mu) (km/s) (sec) (sec)
===========================================================================
6 2.38 - 45.20 SWS01 TDT(WR11) = 1878
---------------------------------------------------------------------------
11 2.38 - 45.20 SWS01 TDT(WR11) = 1878 sec
11 2.38 - 2.60 2.49 SWS06 401 378 527
2.60 - 3.02 2.81 SWS06 400 522 1219
3.02 - 3.52 3.27 SWS06 701 642 2049
3.52 - 4.05 3.785 SWS06 594 434 2640
MgIV 4.05 - 5.30 4.675 SWS06 1415 267 1058 3949
ArII 5.30 - 7.00 6.15 SWS06 1415 263 688 4832
ArIII 7.00 - 12.00 9.50 SWS06 1415 241 2138 7383
NeII, Ne III 12.00 - 16.00 14.25 SWS06 1415 215 1024 8653
SIII 16.00 - 19.50 18.75 SWS06 1415 81 940 9826
ArIII, OIV 19.50 - 29.50 25.25 SWS06 1415 141 1262 11369
SIII, NeIII 29.50 - 45.20 37.35 SWS06 1415 46 1442 13119
SWS06 Merged TDT(WR11) = 8785 sec
---------------------------------------------------------------------------
48a 2.38 - 45.20 SWS01 TDT(WR48a)= 1878 sec
48a 2.38 - 2.60 2.49 SWS06 83 378 527
2.60 - 3.02 2.81 SWS06 130 522 1219
3.02 - 3.52 3.27 SWS06 409 642 2049
3.52 - 4.05 3.785 SWS06 524 434 2640
MgIV 4.05 - 5.30 4.675 SWS06 1400 365 1058 3949
ArII 5.30 - 7.00 6.15 SWS06 1400 363 688 4832
ArIII 7.00 - 12.00 9.50 SWS06 1400 353 2138 7383
NeII, Ne III 12.00 - 16.00 14.25 SWS06 1400 336 1024 8653
SIII 16.00 - 19.50 18.75 SWS06 1400 137 940 9826
ArIII, OIV 19.50 - 29.50 25.25 SWS06 1400 214 1262 11369
29.50 - 33.00 31.40 SWS06 31 350 11863
SWS06 Merged TDT(WR48a) = 8785 sec
---------------------------------------------------------------------------
70 2.38 - 45.20 SWS01 TDT(WR70) = 1878 sec
---------------------------------------------------------------------------
78 2.38 - 45.20 SWS01 TDT(WR78) = 1878 sec
---------------------------------------------------------------------------
98a 2.38 - 45.20 SWS01 TDT(WR98a) = 1878 sec
---------------------------------------------------------------------------
104 2.38 - 45.20 SWS01 TDT(WR104) = 1878 sec
---------------------------------------------------------------------------
112 2.38 - 45.20 SWS01 TDT(WR112) = 1878 sec
---------------------------------------------------------------------------
118 2.38 - 45.20 SWS01 TDT(WR118) = 1878 sec
---------------------------------------------------------------------------
135 2.38 - 45.20 SWS01 TDT(WR135) = 1878 sec
---------------------------------------------------------------------------
136 2.38 - 45.20 SWS01 TDT(WR136) = 1878 sec
---------------------------------------------------------------------------
137 2.38 - 45.20 SWS01 TDT(WR137) = 1878 sec
---------------------------------------------------------------------------
140 2.38 - 45.20 SWS01 TDT(WR140) = 1878 sec
140 2.38 - 2.60 2.49 SWS06 55 378 527
2.60 - 3.02 2.81 SWS06 60 522 1219
3.02 - 3.52 3.27 SWS06 150 642 2049
3.52 - 4.05 3.785 SWS06 151 434 2640
MgIV 4.05 - 5.30 4.675 SWS06 2720 120 1058 3949
ArII 5.30 - 7.00 6.15 SWS06 2720 114 688 4832
ArIII 7.00 - 12.00 9.50 SWS06 2720 96 2138 7383
NeII 12.00 - 14.90 13.45 SWS06 2720 42 742 8328
SWS06 Merged TDT(WR140) = 7936 sec
---------------------------------------------------------------------------
147 2.38 - 45.20 SWS01 TDT(WR147) = 1878 sec
147 2.38 - 2.60 2.49 SWS06 81 378 527
2.60 - 3.02 2.81 SWS06 89 522 1219
3.02 - 3.52 3.27 SWS06 216 642 2049
3.52 - 4.05 3.785 SWS06 222 434 2640
MgIV 4.05 - 5.30 4.675 SWS06 900 94 1058 3949
ArII 5.30 - 7.00 6.15 SWS06 900 92 688 4832
ArIII 7.00 - 12.00 9.50 SWS06 900 85 2138 7383
NeII, Ne III 12.00 - 16.00 14.25 SWS06 900 76 1024 8653
SIII 16.00 - 19.50 18.75 SWS06 900 27 940 9826
ArIII, OIV 19.50 - 29.50 25.25 SWS06 900 58 1262 11369
SIII, NeIII 29.50 - 37.50 33.50 SWS06 900 26 1468 13149
SWS06 Merged TDT(WR147) = 8785 sec
===========================================================================
Table 4. Photometric Data (fluxes in Jansky)
------------------------------------------------------------------------
WR K L' M N1 N2 N3 Q0 IRAS IRAS IRAS
[2.2] [3.8] [4.6] [8.4] [9.7] [12.9] [18.6] 12 25 60
------------------------------------------------------------------------
6 2.9 1.9 1.8 1.1 0.62 0.8
11 110.0 56.2 45.8 19.4 18.5 18.2 14.0 19.4 8.7 4.3
48a 7.5 46.3 71.9 99.9 76.5 94.0 43.6
70 3.9 10.2 12.6 6.5 2.0
78 6.8 3.9 2.8 1.3 0.61
98a 7.8 55.7 82.6 77.2 46.5 61.6 25.2 51.6 14.1
104 78.2 335.6 457.8 440.0 313.0 360.9 209.3 411.5 140.2 -
112 12.0 72.8 122.6 151.2 154.1 157.4 75.8 150.4 74.0 19.3
118 23.6 86.7 103.9 70.4 21.7
135 1.2 0.7 0.8
136 3.9 2.8 2.7 1.3 0.6
137 1.9 1.6 1.7
140 15.3 23.7 25.6 11.0 9.0 5.4 2.0 5.4 1.1
147 14.6 14.5 11.8 5.4 3.4 4.1 4.3 5.3 3.1
------------------------------------------------------------------------
Table 5. Priorities, Time and Coordination with other consortia.
================================================================================
Name Sp.type Priority TDT LWS
PHT
---- ------- -------------- ------------------------------------
Orion G.C. Orion G.C.
hole hole hole hole
Autumn Spring Autumn Spring
launch launch launch launch
---- ------- ------ ------ ----------------- ----------------- ---
---
WR6 WN5 - 3 SWS01 1878 + +
WR11 WC8+O9I 1 1 SWS01+SWS06 10663 SWS01+SWS06 10663 + +
WR48a WC8+? 2 2 SWS01 1878 SWS01+SWS06 10663
WR70 WC9+B0I 3 - SWS01 1878
WR78 WN7 3 - SWS01 1878 +
WR98a WC9 2 - SWS01 1878
WR104 WC9 2 - SWS01 1878 + +
WR112 WC9 3 - SWS01 1878 + +
WR118 WC9 3 - SWS01 1878 + +
WR135 WC8 3 3 SWS01 1878 SWS01 1878
WR136 WN6 3 3 SWS01 1878 SWS01 1878 +
WR137 WC7+O9 3 3 SWS01 1878 SWS01 1878 +
WR140 WC7+O4 2 2 SWS01+SWS06 9814 SWS01+SWS06 9814 + +
WR147 WN8+? 1 1 SWS01+SWS06 10663 SWS01+SWS06 10663 + +
--------------------------------------------------------------------------------
Priority 1 total TDT (s) 21326 21326
Priority 1 total TDT (hr) 5.9 5.9
Priority 1 total TDT (%) 43 43
Priority 2 total TDT (s) 15448 20447
Priority 2 total TDT (hr) 4.3 5.7
Priority 2 total TDT (%) 31 42
Priority 3 total TDT (s) 13146 7512
Priority 3 total TDT (hr) 3.7 2.1
Priority 3 total TDT (%) 26 15
------- + ------- +
Grand total TDT (s) 49920 49315
Grand total TDT (hr) 13.9 13.7
================================================================================
<=== autumn_launch_targets ===>
1, "SWS01", 1., "N", "WR11 ", 8.13319, -47.18833, 1950, 0., 0., 1878, 2
2, "SWS06", 1., "N", "WR11 ", 8.13319, -47.18833, 1950, 0., 0., 8785, 0
3, "SWS01", 2., "N", "WR48a ", 13.15750, -62.45028, 1950, 0., 0., 1878, 0
4, "SWS01", 3., "N", "WR70 ", 15.42914, -58.40917, 1950, 0., 0., 1878, 0
5, "SWS01", 3., "N", "WR78 ", 16.81344, -41.77139, 1950, 0., 0., 1878, 0
6, "SWS01", 2., "N", "WR98a ", 17.63333, -30.51722, 1950, 0., 0., 1878, 0
7, "SWS01", 2., "N", "WR104 ", 17.98364, -23.62889, 1950, 0., 0., 1878, 0
8, "SWS01", 3., "N", "WR112 ", 18.22689, -18.99639, 1950, 0., 0., 1878, 0
9, "SWS01", 3., "N", "WR118 ", 18.48244, -10.02417, 1950, 0., 0., 1878, 0
10, "SWS01", 3., "N", "WR135 ", 20.16689, 36.04694, 1950, 0., 0., 1878, 0
11, "SWS01", 3., "N", "WR136 ", 20.17142, 38.20417, 1950, 0., 0., 1878, 0
12, "SWS01", 3., "N", "WR137 ", 20.21094, 36.50778, 1950, 0., 0., 1878, 0
13, "SWS01", 2., "N", "WR140 ", 20.31297, 43.69528, 1950, 0., 0., 1878, 14
14, "SWS06", 2., "N", "WR140 ", 20.31297, 43.69528, 1950, 0., 0., 7936, 0
15, "SWS01", 1., "N", "WR147 ", 20.58161, 40.17722, 1950, 0., 0., 1878, 16
16, "SWS06", 1., "N", "WR147 ", 20.58161, 40.17722, 1950, 0., 0., 8785, 0
<=== spring_launch_targets ===>
1, "SWS01", 3., "N", "WR6 ", 6.86892, -23.86444, 1950, 0., 0., 1878, 0
2, "SWS01", 1., "N", "WR11 ", 8.13319, -47.18833, 1950, 0., 0., 1878, 3
3, "SWS06", 1., "N", "WR11 ", 8.13319, -47.18833, 1950, 0., 0., 8785, 0
4, "SWS01", 2., "N", "WR48a ", 13.15750, -62.45028, 1950, 0., 0., 1878, 5
5, "SWS06", 2., "N", "WR48a ", 13.15750, -62.45028, 1950, 0., 0., 8785, 0
6, "SWS01", 3., "N", "WR135 ", 20.16689, 36.04694, 1950, 0., 0., 1878, 0
7, "SWS01", 3., "N", "WR136 ", 20.17142, 38.20417, 1950, 0., 0., 1878, 0
8, "SWS01", 3., "N", "WR137 ", 20.21094, 36.50778, 1950, 0., 0., 1878, 0
9, "SWS01", 2., "N", "WR140 ", 20.31297, 43.69528, 1950, 0., 0., 1878, 10
10, "SWS06", 2., "N", "WR140 ", 20.31297, 43.69528, 1950, 0., 0., 7936, 0
11, "SWS01", 1., "N", "WR147 ", 20.58161, 40.17722, 1950, 0., 0., 1878, 12
12, "SWS06", 1., "N", "WR147 ", 20.58161, 40.17722, 1950, 0., 0., 8785, 0