Winds of very low metallicity OB stars: crossing the frontier of the Magellanic Clouds
Very low metallicity massive stars are a key ingredient for our understanding of the early Universe because of their connection with the dominant conditions at that time, the reionization epoch and long-GRBs. In the studies of massive stars radiation driven winds play a crucial manifold role, being a chief agent of stellar evolution, altering the optical diagnostics for parameter determination and injecting radiative and mechanical energy into their surroundings. However, the theory of radiation driven winds has only be tested down to SMC metallicities and some important open questions remain: the existence of solar-metallicity stars with weak winds and very recent evidence of relatively strong winds in metal-poor stars.
We have secured VLT optical spectra of a sample of early-type massive stars in IC 1613, a very metal poor (~<0.1Zo) irregular galaxy of the Local Group that represents the next step towards low metallicities after the SMC. We request low resolution COS spectra (COS/FUV-G140L) of a sub-set of OB stars probing different wind regimes. The wind lines in the 1150-1800A range, together with the optical spectra, will allow us to derive consistently the photospheric and wind parameters of the sample. Results will be interpreted in the context of both evolutionary and radiatively driven winds theories, testing the current paradigm at unexplored low metallicities and increasing our knowledge of massive stars under conditions closer to those of the deep Universe.
COS enhanced sensitivity will allow us to perform for the first time detailed studies of **resolved** OB stars in an environment with poorer metal content than the SMC.
This proposal consists of COS/FUV spectroscopy of O and early-B stars in a Local Group Galaxy, IC1613.
All targets are visited once (except for target-2, which is visited twice).
All visits consist of 2 or more orbits, to accumulate exposure time.
The configuration is PSA, G140L, and central-lambda=1105, SEGMENT-A (B is off).
All FP-POS are used, but less Texp is given to FP-POS=1 since in this configuration the blue edge of the P-Cygni of CIII1176 may be lost if the terminal velocity was high.
The astrometry of the targets is accurate, and ACQ/IMH is preferred; for the brightest targets, PEAKXD+PEAKD are used.
Parallels consist of WFC3/UVIS imaging of interesting positions of the galaxy, but using orient angles that do not hamper schedulability. The use of wide filters has higher priority, and narrow filters are used if enought time is spent in the visit.
HOT STARS
12
false
0.0
0.0
false
false
false
false
SUPPORTED
EXT-STAR
MAIN SEQUENCE O
69217
J2000
J2000
TYPE=O3-4Vf, B-V = -0.225, E(B-V) = 0.105, F-CONT(1300) =33E-16
EXT-STAR
MAIN SEQUENCE O
65426
J2000
J2000
TYPE=O5-6Vf, B-V = -0.202, E(B-V) = 0.118, F-CONT(1300) =14E-16
EXT-STAR
SUPERGIANT O
62024
J2000
J2000
TYPE=O5If, B-V = -0.161, E(B-V) = 0.149, F-CONT(1300) =1E-15
EXT-STAR
SUPERGIANT O
67559
J2000
J2000
TYPE=O7I(f), B-V = -0.201, E(B-V) = 0.109, F-CONT(1300) =18E-16
EXT-STAR
SUPERGIANT O
63932
J2000
J2000
TYPE=O9I, B-V = -0.206, E(B-V) =0.074, F-CONT(1300) =35E-16
EXT-STAR
SUPERGIANT O
62390
J2000
J2000
TYPE=O9.5I, B-V = -0.135, E(B-V) = 0.135, F-CONT(1300) =65E-16
EXT-STAR
B0-B2 III-I
69336
J2000
J2000
TYPE=B0Ia, B-V = -0.152, E(B-V) = 0.088, F-CONT(1300) =9E-15
EXT-STAR
B0-B2 III-I
60449
J2000
J2000
TYPE=B1.5Ia, B-V = -0.128, E(B-V) = 0.052, F-CONT(1300) =6.0E-15
COS/FUV
Spectroscopic
No
No
G140L
1105
COS/FUV
Spectroscopic
No
No
G140L
1105
COS/FUV
Spectroscopic
No
No
G140L
1105
COS/FUV
Spectroscopic
No
No
G140L
1105
COS/FUV
Spectroscopic
No
No
G140L
1105
COS/FUV
Spectroscopic
No
No
G140L
1105
COS/FUV
Spectroscopic
No
No
G140L
1105
COS/FUV
Spectroscopic
No
No
G140L
1105
WFC3/UVIS
Imaging
No
No
F336W
WFC3/UVIS
Imaging
No
No
F438W
WFC3/UVIS
Imaging
No
No
F555W
WFC3/UVIS
Imaging
No
No
F502N
WFC3/UVIS
Imaging
No
No
F657N
WFC3/UVIS
Imaging
No
No
F673N
WFC3/UVIS
Imaging
No
No
F336W
WFC3/UVIS
Imaging
No
No
F438W
WFC3/UVIS
Imaging
No
No
F555W
WFC3/UVIS
Imaging
No
No
F502N
WFC3/UVIS
Imaging
No
No
F657N
WFC3/UVIS
Imaging
No
No
F673N
WFC3/UVIS
Imaging
No
No
F336W
WFC3/UVIS
Imaging
No
No
F438W
WFC3/UVIS
Imaging
No
No
F555W
WFC3/UVIS
Imaging
No
No
F502N
WFC3/UVIS
Imaging
No
No
F657N
WFC3/UVIS
Imaging
No
No
F673N
WFC3/UVIS
Imaging
No
No
F336W
WFC3/UVIS
Imaging
No
No
F438W
WFC3/UVIS
Imaging
No
No
F555W
WFC3/UVIS
Imaging
No
No
F502N
WFC3/UVIS
Imaging
No
No
F657N
WFC3/UVIS
Imaging
No
No
F673N
WFC3/UVIS
Imaging
No
No
F336W
WFC3/UVIS
Imaging
No
No
F438W
WFC3/UVIS
Imaging
No
No
F555W
WFC3/UVIS
Imaging
No
No
F502N
WFC3/UVIS
Imaging
No
No
F657N
WFC3/UVIS
Imaging
No
No
F673N
WFC3/UVIS
Imaging
No
No
F336W
WFC3/UVIS
Imaging
No
No
F438W
WFC3/UVIS
Imaging
No
No
F555W
WFC3/UVIS
Imaging
No
No
F502N
WFC3/UVIS
Imaging
No
No
F657N
WFC3/UVIS
Imaging
No
No
F673N
WFC3/UVIS
Imaging
No
No
F336W
WFC3/UVIS
Imaging
No
No
F438W
WFC3/UVIS
Imaging
No
No
F555W
WFC3/UVIS
Imaging
No
No
F502N
WFC3/UVIS
Imaging
No
No
F657N
WFC3/UVIS
Imaging
No
No
F673N
WFC3/UVIS
Imaging
No
No
F336W
WFC3/UVIS
Imaging
No
No
F438W
WFC3/UVIS
Imaging
No
No
F555W
WFC3/UVIS
Imaging
No
No
F502N
WFC3/UVIS
Imaging
No
No
F657N
WFC3/UVIS
Imaging
No
No
F673N
The scheduling data was generated by CASM 20.0.
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true
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true
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