Circumstellar Environments
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
The Team
Historical Group (from IRA-Noto):
G.Umana, C.S. Buemi INAF-OACt
C. Trigilio
INAF-OACt and Università di Catania
P. Leto
INAF-IRA, Noto
PhD students:
L. Cerrigone, CfA-Università di Catania
S. Dolei, P. Manzitto, C. Siringo
Università di Catania
Collaborators:
F. Leone, Università di Catania
J. Hora, G. Fazio, M. Marengo SAO-CfA
C. Burigana INAF-IASF
H. Olofsson OSO, G. Giardino (ESA), R. Paladini (JPL)
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
The project
The study of circumstellar environments
by means of radio observations

Radio techniques very useful in multi-frequency
approaches

Unique for some classes of Galactic objects
Circumstellar environments:
• Coronae around active stellar systems
• Stellar Magnetosphere
• Stellar ejecta, late stage of stellar evolution
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
The project
Funds (since 2004):
Besides normal (small) INAF science funding….
G. Umana
2005-2007
ASI-Planck
Science
18 k€
2007-2008
ASI-Planck
Science
7.5 k€
2006-2008
INAF/Alma
6.2 k€
Visiting Committee
Catania, 17 dicembre 2007
•
•
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Radio Emission from CP stars
Anomalous abundances
Strong (>3000 G) dipolar magnetic field
Variability (continuum, lines, B)
- Oblique Rotator Model
radio
Explained in terms of oblique rotator model
Radio emission (also variable ) consistent with
Gyrosynchrotron plus a coherent component
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
Radio Emission from CP stars
Goal
Understanding the origin of variable radio emission from CP
Method
By modeling the radio flux density light-curve
VLA and ATCA project (multi-frequency, multi-configuration)
Principal Results:
o
o
o
o
G. Umana
Full coverage of radio curve at different frequency for
3 stars
Development of a 3D code to reconstruct the
magnetosphere of CP and modeling of radio light curve
Discovery of a new component in the radio emission
Use of coherent emission as a period marker
Visiting Committee
Catania, 17 dicembre 2007
The 3D code for radio emission
-Gyrosynchrotron from the magnetosphere
18 cm, 4 cm, 1 cm
Good agreement with observations
Trigilio C., Leto, P., Umana, G., Buemi, C., Leone, F., 2004
Leto P., Trigilio, C., Buemi, C. Umana, G., Leone, F. ,2006
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
CU Vir: the coherent radio component
Discovery of a new component of radio emission:
• occurring only at particular rotational phases
• 100% circularly polarized
• highly directive
• persistent over years
Consistent with
Cyclotron Maser Emission
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
CU Vir: the coherent radio component
Consistent with
Cyclotron Maser Emission
• occurring only at particular rotational
phases
• persistent over years
Marker of the rotational period
CU Virginis is slowing down
dP/dt ~ 10-9 s yr-1
Trigilio C., Leto, P., Umana, G., Buemi, C., Leone, F., 2008
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
Stellar Ejecta
Observed around stellar objects in late evolutionary phases:
-AGB  PNe
Mass-loss  CSE
-LBV
Open questions:
o Shaping: mass-loss (asymmetric) or evolution in an asymmetric
environment?
o Mass and T (gas & dust content)
o Multiple components (different mass-loss episodes?)
o Chemistry and its evolution with time (photodissociation, shocks)
o Chemical evolution of Galaxy (processed material return to ISM)
o Ideal laboratory to study wind/shocks interaction with ISM
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
Stellar Ejecta: AGB PNe
MMS 1 -8 Mo
104 L
102 L
yrs
~800
~1000
UV
* Visible
1 L
10-2 L
10-4 L
IR-radio
O
B
G. Umana
IR
IR-farIR
A
F
G
Visiting Committee
Catania, 17 dicembre 2007
K
M
Hunting for Young PNe
Goal
Method
Understanding the shaping of PNe, through observation of YPNe
where the shaping mechanism is still active
Select a sample of TO (AGBPNe) objects; Detect radio to find YPNe

far-IR characteristics (excess)
 Optical characteristics
 B spectral type
 spectral and photometric variability
-The onset of ionization can be marked by the presence of free-free emission…
VLA and ATCA project (multi-frequency, multi-configuration) 42 objects
Principal Results:
o
o
o
o
G. Umana
Detected 17 sources; Established their evolutionary status (YPNe)
Other 25 objects are genuine hot post-AGB stars.
Radio spectra consistent with a PN in the early stage of its
evolution
High-resolution mapping Bi-polar morphology
Visiting Committee
Catania, 17 dicembre 2007
YPNe: sub-arc observations
VLA-A,
Radio morphology: bi-polar
shaping is already active!
3.6cm
1
Cerrigone,L., Umana, G., trigilio, C., Buemi, C., Leto, P. ., 2008
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
IRAS 22568+6141
Umana, G., Trigilio, C., Cerrigone, L., Buemi, C., Leto, P., 2008
VLA-C, 3.6cm
VLA-A, 3.6cm
1
Total flux= 32mJy
Central component 1.65 0.05 mJy
Consistent with stellar wind? (Mass-loss)
H-alpha
G. Umana
new VLA, high resolution, multi-frequency data
already available (AU119), waiting for reduction!
Visiting Committee
Catania, 17 dicembre 2007
CSE: the dust component
Goal
Method
Understanding the dust contribution to the shaping
Inspecting the dust properties of envelope in TO (AGBPNe)
objects:
-systematic differences between radio detected (YPNe) and post-AGB?
SST project on YPNe, part of the SST-GTO on Stellar ejecta (PI G. Fazio)
IRAC + IRS observations of 42 TO (with radio infos)
Principal Results:
o
o
o
o
o
G. Umana
CSE around TO generally very compact (not resolved by IRAC)
IRS spectra dominated by thermal dust emission plus spectral
structures due to dust (crystalline silicates)
besides recombination lines, no evident differences between radio (YPNe)
and not radio detected (hot post-AGB) objects.
about 50% of the sample shows mixed chemistry
necessity to introduce big grains to fit SEDs
Visiting Committee
Catania, 17 dicembre 2007
The dust component: Results
Silicates
[ArII]
When SED (up to mm) are modeled:
- necessity to consider multi-component CSE
- big grains (0.05-100 m)
[NeII]
PAH PAH Silicates
- IRS spectra dominated by thermal dust emission plus spectral
structures due to crystalline silicates
- part of the sample shows mixed chemistry:
not consistent with evolution theory
- Consistent with a reservoir of O-rich material, probably
Cerrigone, L., Hora, J., Umana, G., Trigilio, C., 2007
Cerrigone, L., PhD Thesis, 2008
G. Umana
an equatorial disk (PPNe Red Rectangle)
 strong clue for stellar ejecta being collimated by
such structures!
Visiting Committee
Catania, 17 dicembre 2007
MMS > 25 Mo
Stellar Ejecta: LBV
log L/L ~ 5.0-6.3
 strong mass-loss
 Variability
 Outbursts
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
~ 10-6 ÷10-4 Myr-1
ΔV ~ 1-2 mag
LBVs: the ionized gas
Understanding the LBV phenomenon through the study
of their ejecta (morphology and physics of the nebula)
Goal
Determine the properties of the radio emission, tracing the ionized
gas component of the ejecta
-Symmetric versus Asymmetric morphology
Method
- Mass-loss of the central objects (current-day mass-loss)
VLA Multi-frequency, multi-configuration project
Principal Results:
o
o
o
o
Radio morphologies in general asymmetric and structured
High-resolution allows to resolve the core component
High-resolution, multi-frequency allows to determine mass-loss
Radio observations more efficient than usual H (no extinction)
essential to probe the ionized component in strongly reddened object
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
IRAS 18576+0341
LBVs in Radio
Probing the ionized component in a very dusty environment
Strongly reddened object: no optical counterpart
-Multi-frequency, high resolution VLA observations:
-a core component (LBV’s wind)
-an extended, asymmetric nebula
Current day mass-loss
3.7 10-5 Myr-1
B0-B0.5 I, Teff ~ 2.6 104 K
Umana, G., Buemi, C.S., Trigilio, C. , Leto, P. et al., 2005
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
VLA-A, C-band
LBVs: the dust component
Understanding the LBV phenomenon through the study
of their ejecta (morphology and physics of the nebula)
Goal
Determine the properties of the mid-IR emission, tracing the dust
component of the ejecta
-Symmetric versus Asymmetric morphology
Method
- Comparison with ionized gas component to derive clues for shaping
VISIR@VLT project
multi-frequency sub-arcsec imaging
Principal Results:
o
o
Ejecta morphologies: highly structured
Thermal dust morphologies DIFFERENT from radio.
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
IRAS 18576+0341
Mapping with VISIR@VLT
pixel scale 0.075
IRS@SST
11.26 m
12.27 m
G. Umana
17.65 m
Visiting Committee
Catania, 17 dicembre 2007
IRAS 18576+0341
Comparison between ionized gas and dust:
sub-arcsec mapping
4
-4
VLA-A, 5 GHz (6cm)
VISIR 12.25 m
Clues on mass-loss and shaping:
A) Mass-loss can occur asymmetrically; outflows may be shaped by dusty structures
B) dust distribution not homogeneous
dust competes with gas in absorbing UV radiation: holes in dust allow gas to glow!
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
LBVs: ionized gas and dust comparison
VLA-A
VISIR
Different situation in HD168625
- The ionized gas appears contained by dust:
- Outflow channeled by a dusty equatorial torus??
kinematical information necessary!
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
3.6cm
12.25 m
LBV: more on the dust component
Goal
Determine the characteristics of dust component: yield to ISM
Chemistry; mass-loss history
Method
Determine mid-IR spectral and morphological properties
Modeling the SEDs (CLOUDY)  Mass-loss history
-SST project on Galactic LBVs, part of the SST-GTO on Stellar ejecta (PI G. Fazio)
IRAC+IRS (low + high res) of nine Galactic LBV
-SAGE Collaboration on LBVs in MCs (IRAC+IRS+MIPS)
First Results:
o Dusty CSE around Galactic LBV can be very extended
o
o
o
G. Umana
Both regular (spherical) and asymmetric morphology observed.
IRS spectra: dominated by emission lines and dust spectral features (PAHs)
[Fe II] mid-IR lines detected: possible diagnostics for shocks
Visiting Committee
Catania, 17 dicembre 2007
Wray17-96
SST-IRAC mosaic
IRAC LBV GTO program
G. Umana
Stellar ejecta
Visiting Committee
Catania, 17 dicembre 2007
Stellar ejecta: the future
In the next years new instrumentations will come on-line
ALMA: mm interferometer ( 30-900 GHz)
spectral and continuum capabilities (sub-mJy) ,
sub-arcsec imaging 2011
EVLA: cm interferometer (1.4-50 GHz) :
spectral and continuum capabilities (sub-mJy) ,
sub-arcsec imaging 2009
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
Stellar ejecta:the future
Stellar ejecta possible foregrounds for CMB:
- from a feasibility study ~400 CSE will be detected
by PLANCK (Umana, G. Burigana, C., Trigilio, C.- 2006)
- PLANCK will provide flux measurements, between 30
and 900 GHz, for the radio brightest PNe SEDs
Umana, Leto, Trigilio, Buemi, Toscano, Manzitto, Dolei,
Cerrigone, 2008
(based on 43 GHz single dish INAF-IRA teleacope Obs)
PLANCK mission,
full sky coverage
(30 to 900 GHz)-end 2008
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
Stellar ejecta:ALMA
ALMA will provide detailed (sub-arcsec, sub-mJy) maps of:
 ionized gas
continuum (30 GHz…..)
morphology
 molecular gas
 dust
CO (100 GHz)
continuum (100 GHz…)
morphology (Kinematic)
morphology
Morphological and spectral studies of different components
coexisting in the ejecta  CLUES on shaping
ionized gas
SYNERGIES
ALMA
VISIR@VLT
HST
EVLA
(sub-arc, sub-mJy)
(sub-arc, mJy)
(sub-arc)
(sub-arc, sub-mJy)
G. Umana
continuum
continuum (1.4-50 GHz)
RRLs (1.4-50 GHz)
molecular gas CO
H2 (near-IR)
Dust
continuum
continuum (mid-IR)
Visiting Committee
Catania, 17 dicembre 2007
ALMA-2011+……
putting together the pieces
Radio jet that
makes its way
through the CO
cocoon
Dusty disk/torus
Molecular Cocoon
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
Stellar ejecta:ALMA
mm and submm observations provide strong constraints for SED modeling
Post-AGB stars
mm obs MAMBO@Iram 30m
+ SEDs modeling (DUSTY):
 = 0.9-1.6
R =1016 10 17 cm
dM/dt~ 10-6-10-5
ALMA: Detailed maps of CSE
dimension, structure…
VERY strong constraints to the
SED Modeling!
Buemi, C, Umana, G., Leto,P., Trigilio, C 2007
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
The link to the Catania University
Radioastronomy (C. Trigilio)
Galactic Radiosources (G. Umana)
Undergraduate course (Physics)
Lectures for PhD program
All the students trained at INAF-IRA 32m Radiotelescope:
acquisition techniques,
data reductions …..
PhD students:
L. Cerrigone, Infrared and Radio properties of YPNe
Science for ALMA
CfA-Università di Catania Thesis defence next February
Università di Catania, III year
Science for ALMA
PLANCK, HERSCHEL
C. Siringo, SiO maser in CSE
Science for ALMA
P. Manzitto, SEDs modeling of PNe
Università di Catania, begin III year
S. Dolei, Radio modeling of PNe
Università di Catania, begin II year
G. Umana
Visiting Committee
Catania, 17 dicembre 2007
Science for ALMA
PLANCK, HERSCHEL