Spectroscopic study of massive, hot stars
and their winds
Projects for future bachelor, master, or doctoral theses
Brankica Kubátová (née Šurlan)
brankica.kubatova@asu.cas.cz
Stellar Physics Department
Astronomical Institute of the CAS
February 24, 2023
Motivation
• To understand the evolution and fate of massive stars in the Universe accurate mass-loss
rates are crucial.
• Answers regarding the evolution of massive stars rely on theoretical and observational
progress in our detailed understanding of stellar winds as a function of metallicity : ˙M = f(Z).
• Mass-loss recipes affect the nature and properties
of the end products of stellar evolution, including
SN types and compact remnants, and ultimately
gravitational-wave progenitors (LIGO/Virgo:
Abbott et al. 2016; Abbott et al. 2020).
Brankica Kubátová (née Šurlan) Spectroscopic study of massive, hot stars and their winds February 24, 2023 2 8
XSHOOTU collaboration: ULLYSES & XSHOOTER
•
https://massivestars.org/xshootu/
• 14 Working Groups
• WG4 - Wind Structure
Point of Contact:
Brankica Kubátová
• The NASA Hubble Space Telescope (HST) - uniformly observed sample of the
fundamental astrophysical parameter space for each mass regime - including spectral type,
luminosity class, and metallicity for massive OB stars in SMC (Z=0.5 Z⊙), LMC
(Z=0.2 Z⊙), NGC 3109 (Z=0.1-0.2 Z⊙), and Sextans A (Z=0.1 Z⊙).
• Spectral types O2-B1.5, supergiants B2-B9, 11 WR stars (4 close binary systems); about
240 stars.
• HST observations ( FUV: 937-1792 Å+ archive data; NUV: 1607-3119 Å;
OPT: 2900-5700 Å; NIR: 5240-10270 Å); XSHOOTER observations ( UVB: 300-559.5
nm; OPT: 559.5-1024 nm; NIR:1024-2480 nm).
• These observed data will be used in further bachelor, master, or PhD theses.
Brankica Kubátová (née Šurlan) Spectroscopic study of massive, hot stars and their winds February 24, 2023 3 8
Bachelor thesis topic 1
• UV Spectroscopy of OB-type Stars
Using archival data (IUE, FUSE, HST)
Understanding diagnostic lines for mass-loss rate, terminal velocity, and clumping properties
determination
900 950 1000 1050 1100 1150 1200
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flux/erg/s/Å
1e−12
1200 1250 1300 1350 1400 1450 1500
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flux/erg/s/Å
1500 1525 1550 1575 1600 1625 1650 1675 1700
λ/Å
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flux/erg/s/Å
Merged spectrum of Copernicus and IUE UV high-resolution observations
of the supergiant ζ Puppis (Pauldrach et al., 1994). HST observation of the Sk-69 50.
Brankica Kubátová (née Šurlan) Spectroscopic study of massive, hot stars and their winds February 24, 2023 4 8
Bachelor thesis topic 2
• Optical (infrared) Spectroscopy of OB-type Stars
Using archival data (HST, XShooter, ...)
Understanding diagnostic lines for stellar and wind properties determination
3000 3250 3500 3750 4000 4250 4500 4750 5000
0.0
0.5
1.0
norm.flux
5000 5250 5500 5750 6000 6250 6500 6750 7000
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1.0
norm.flux
7000 7200 7400 7600 7800 8000 8200
λ/Å
0.0
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1.0
norm.flux
XSHOOTER observation of the Sk-66 171.
Brankica Kubátová (née Šurlan) Spectroscopic study of massive, hot stars and their winds February 24, 2023 5 8
Master thesis topic
• Spectral modelling of OB-type stars
Analysis of only one chosen star
Using optical, UV, IR archival data
Using PoWR NLTE stellar atmosphere codes
Determination of stellar and wind parameters
Šurlan et al., 2013, A&A, 559, A130
Brankica Kubátová (née Šurlan) Spectroscopic study of massive, hot stars and their winds February 24, 2023 6 8
PhD theses topics
• How wind properties change along spectral and luminosity classes at different
metallicity?
Wind properties
▶ Mass-loss rate
▶ Terminal velocity
▶ Clumping properties
Brankica Kubátová (née Šurlan) Spectroscopic study of massive, hot stars and their winds February 24, 2023 7 8
PhD theses topics
• How wind properties change along spectral and luminosity classes at different
metallicity?
• Empirical study - quantitative spectroscopy
Analysis of larger sumple of stars using the newest HST and XSHOOTER observations
Using NLTE stellar atmosphere codes: PoWR, CMFGEN, FASTWIND, and/or 3D MCRT code
Calculation of synthetic spectra and their comparison with observations to determine stellar and
wind parameters (e.g., Šurlan et al., 2013, A&A, 559, A130).
Brankica Kubátová (née Šurlan) Spectroscopic study of massive, hot stars and their winds February 24, 2023 7 8
PhD theses topics
• How wind properties change along spectral and luminosity classes at different
metallicity?
• Theoretical study
Contribution to the development of sophisticated radiative transfer and/or hydro-dynamic codes
for stellar atmospheres and wind modelling (e.g., Šurlan et al., 2012, A&A, 541, A37; Kubát &
Kubátová, 2021, A&A, 655, A35; Krtička, Kubát & Krtičková, 2022, A&A, 659, A117).
Outputs: spectral energy distribution, line profiles or wind structure (T, ρ, V).
0
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-1 -0.5 0 0.5 1
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Normalizedflux
Dimensionless frequency
Velocity [km/s]
χ0=100
L0=1
L0=0.7
L0=0.5
L0=0.2
smooth
Brankica Kubátová (née Šurlan) Spectroscopic study of massive, hot stars and their winds February 24, 2023 7 8
Contacts
• For all questions and further discussions about possible bachelor, master, or PhD theses,
please contact:
• Mgr. Brankica Kubátová (née Šurlan), Ph.D.
brankica.kubatova@asu.cas.cz
• doc. RNDr. Jiří Kubát, CSc.
jiri.kubat@asu.cas.cz
Completed PhD thesis: see here
Completed MSc. theses: see here
References: J. Kubát & B. Kubátová
• We will be happy to share our knowledge and experience with you and to help and to lead
you to successfully finishing of your study.
Brankica Kubátová (née Šurlan) Spectroscopic study of massive, hot stars and their winds February 24, 2023 8 8