ON THE RELEVANCE AND
FUTURE
OF
UV ASTRONOMY
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
¾The relevance of the UV spectral range for
astrophysics
¾What is available now?
¾Instrumental requirements for the future
¾Network for UV Astrophysics (NUVA)
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
1. The relevance of the UV spectral
range for astrophysics
The UV range supplies a richness of experimental data which is
unmatched by any other domain for the study of hot plasma with
temperatures in between 102K and 105K. ALL the resonance lines
of ALL the elements are in the UV.
Diffuse baryonic component of the Universe – warm/hot gas (the
largest filling factor by volume)
The electronic transitions of the most abundant molecules, such as
H2, OH, or CO, are observed in this range which is also the most
sensitive to the presence of large molecules such as the PAHs.
Example: In cool stars you can get in a single shot (a UV spectrum)
information from OI, CII, CIV, NV, FeXII, FeXXII and H2, CO
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
The UV spectrum of TW Hya
(OI, Lyα, CII, CIV, NV, He II H2,CO)
(Herczeg et al 2002)
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
Access to the UV range is required to make
progress in astrophysics
¾
Planets and the origin of life:
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ISM and Formation and Evolution of Stars:
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•
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•
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•
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Accretion physics and disk instabilities
Reverberation mapping and gas distribution around AGNs
(High-redshift) Universe, Galaxies and Galaxy Evolution:
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hot stars atmospheres (and abundance determination) from white dwarfs to hypergiants
cool stars atmospheres and magnetic dissipation phenomena
formation of stars (from the epoch of planet building-up) and accretion physics
Circumstellar material and shells in warm environments, jets, shocks and HH objects
Chemical abundances in supernovae remnants and in the early phases of supernovae explosions
the warm and hot components of the ISM
AGN and Compact Objects:
•
•
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Planetary atmospheres, auroral variability, comets
Circumstellar environment at the epoch of planet building-up
Chemistry in the Early Solar System
Stellar metallicity (0<z<2)
Star formation rates
SN light curves
Intergalactic medium: distribution, physical properties included metallicity
Galactic haloes
High velocity clouds, magnetic buoyancy in galactic disks and disk-halo interaction
Fundamental Physics and Cosmology:
•
Variation of fundamental constants with the gravitational field and redshift
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
ESA Master Themes for 2015-2025 horizon
(Underlined themes: UV range provides instrumental information)
¾ Other worlds and life in the Universe: placing the solar system in
context:
• Formation of stars and planetary systems
• Detection, census and characterization of exoplanets
• Search for extraterrestrial life (biomarkers)
¾ The early Universe:
• Probing inflation
• Investigating dark energy
• The observable Universe taking shape
¾ The evolving violent Universe
• Black holes and galaxy evolution
• Matter under extreme conditions
• SN and the life cycle of matter
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
Key problems in astrophysics that
cannot be solved without UV:
¾ The chemical evolution of the Universe during
80% of its lifetime
¾ The physics of accretion and outflow
¾ The chemistry in proto-solar systems at the time
of planet building-up - Biomarkers
¾ The variation of the fine structure constant with z
and the gravitational potential for 0<z<2
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
1. CHEMICAL EVOLUTION OF THE UNIVERSE
(or THE COSMIC WEB)
Geller & Huchra, 1989
Granada, Sept. 2004
VIRGO: Cosmological N-body simulations (with gas)
JENAM2004-Instrumentation
Ana I Gómez de Castro
Specific targets:
•
•
•
•
•
Mapping the gas distribution
Determination of sizes,
topology
and ionization fraction
Helium re-ionization
Primordial D/H value (and
cross-checks with C/H, N/H,
O/H)
Undepleted elements
(Zn,S,P,N)
Why now?
Paresce, 1984; mapped the ISM distribution
The GALEX survey is expected to identify 105-106
QSOs in the magnitude range 18<mB<20
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
2. The physics of accretion-outflow
Magnetically
locked
THE FRONTIER:
COMPLEX &
ATTRACTIVE
PHYSICS
Pulsars
The CV´s World
-Magnetic,
-Diamagnetic blobs
-Magnetic fields irrelevant
What kind of
magnetic
interaction???
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
PROTOSTARS
Black holes,
AGNs
EXAMPLE: ACCRETION INTO
A MAGNETIZED SOURCE
Basic Assumptions:
• Star & Disk good conductors
•
Star & Disk have different rotation
velocities
As a result:
1.
2.
3.
4.
5.
6.
the field lines are twisted by the
differential rotation
toroidal magnetic flux is generated
out of the poloidal flux.
the toroidal field builds up and the
associated field pressure tends to
push the field lines outward
and inflate them
after the relative star-disk twist angle
exceeds aroun1 rad the field lines
start to expand faster (at an angle of
30o with the disk)
the magnetic link between the star
and the disk.
Granada, Sept. 2004
Adapted from Lovelace et al 1995 (Uzdenski, 2004)
JENAM2004-Instrumentation
Ana I Gómez de Castro
NUMERICAL SIMULATIONS
Initial and final configuration
B=100 G
B=1kG
Kueker et al, 2004
The results are robust: the star-disk-outflow system is self-regulating when
various initial disk densities, stellar dipolar field strengths and primordial field
associated with the disk are tested
(see Goodson et al 1997,1999, Matt et al 2002)
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
Given the temperatures involved
the output is in the UltraViolet
Predicted profiles for
UV semiforbidden lines
Thermal pressure is a
non-negligible
component to load gas
into the field lines and
warm disk wind
solutions are a
reasonable approach
to the disk outflow in
region II.
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
Gómez de Castro & Ferro-Fontan 2004
The observed semiforbidden
lines are broad
Rotation signatures at the
base of the wind
(Gómez de Castro & Verdugo, 2002)
These observations have done with HST/STIS.
This instrumentation or equivalent are not available
any longer in the whole world-wide astronomical
community. As today, ESA has not taken any step
to provide the community with a facility to replace the
lost of the HST/STIS (or COS) capabilities.
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
3. Chemistry in protoplanetary disks
Magnetic
reconnection is
expected not
only in the
stellar
magnetosphere
but also above
the disk up to
some few
stellar radii.
Granada, Sept. 2004
High energy particles
X-Ray radiation:
Heats –up the inner part of the disk.
As the density is high X-ray -> UV
JENAM2004-Instrumentation
Ana I Gómez de Castro
Reconnecting magnetic fields will accelerate the electrons
and heat the plasma
Heating by radiation
from shock waves
Turbulence Onset: Electric
fields accelerate particles
Reconnection: particles are
conducted to the chromosphere
Heyvaerts, Priest, Rust, 1977
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
This also implies that there is a strong and extended radiation field within the 1
inner AU s of protostellar disk
Photodisociation, Photoionization (and Photoevaporation) processes will affect the
chemistry in the protoplanetary disk leading to a Cometary-alike Chemistry
Fluorescence emission from: CO, H2, OH, CS, S2, CO2+, C2 will be pumped by the
UV radiative field.
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
A TOOL to study the circumstellar disk within
1 AU: variability and flaring.
In the “star formation world” we use the word “flaring” just to indicate
a sudden and short increase in the stellar luminosity often
detected in: X-ray or UBV photometry. It is often assumed that
flares are associated with magnetic reconnection events.
However, in the solar system, a rapid release of energy is also
observed in association with:
¾ Shocks between fast and slow components in the wind
¾ Shocks between the wind and the gas in the disk at the latest
stages
¾ Mass ejections associated with instabilities
Is it feasible to distinguish these different types of events???
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
AB DOR “FLARES”:
CIV [uv1] lines
Gómez de Castro 2002
AB Dor Properties:
Age 20-30 Myrs
Rotation Period: 0.51479 d
Surface field: >500 G
Granada, Sept. 2004
Gómez de Castro 2002
JENAM2004-Instrumentation
Ana I Gómez de Castro
The very broad wings are
most probably related with
the interaction of plasma
flows along curved field
lines with remnant gas in
the disk...
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
“Normal” flares
CIRs?
Shock?
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
Technical-Advantages of the UV
• 30 years of experience in UV instrumentation
(from Copernicus to HST)
• High spectral resolution is a well-known
technology
• Normal incidence is more efficient than grazing
incidence
• Electronic molecular transitions are significantly
stronger than vibrational transitions
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
But… the future of UV astronomy seems
rather dark….
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
Instrumental Requirements for the
future
Firstly,
A high resolution (R≈30,000) UV spectrograph with a
sensitivity at least 10 times better than HST/STIS
(COS, WSO/UV) in a mid-size (1.5m-2m) mission.
and then…(2020)
A 4m-6m space mission to provide enough effective area
for high resolution efficient (echelle) spectroscopy.
Imaging capabilities and mid resolution long-slit
spectroscopy are necessary. Some overlap with the
optical range is desirable (up to 5500Å) to guarantee a
good overlap with the 10 m. ground-based telescopes
cosmological studies
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
Actions:
¾ Creation of the Network for UltraViolet Astronomy
(NUVA) to coordinate the efforts of the european
community.
• NUVA will map and review the instrumental
performance of existing and near future capabilities in
the UV on a global scale.
• NUVA will assess for the future needs and develop a
perspective for the future at European scale.
¾ International colaboration
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro
Granada, Sept. 2004
JENAM2004-Instrumentation
Ana I Gómez de Castro