Late Type stars PACS-ST Workshop, Jan 28/29, 2003, MPE Garching Franz Kerschbaum for the UNIVIE PACS...
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Transcript of Late Type stars PACS-ST Workshop, Jan 28/29, 2003, MPE Garching Franz Kerschbaum for the UNIVIE PACS...
Late Type stars
PACS-ST Workshop, Jan 28/29, 2003, MPE Garching
Franz Kerschbaum for the UNIVIE PACS team
PACS-ST Workshop, Jan. 2003 2Late type stars
AGB-Mass Loss Scenario
Kolenberg (1998) after Sedlmayr (1990)
PACS-ST Workshop, Jan. 2003 3Late type stars
Fields of special interest
• Physics/chemistry of the inner parts of nearby circumstellar envelopes (CSE)– chemistry, cooling(, dynamics by HIFI)
• Mass loss mineralogy• Mass loss history
– Detailed structure of spatially resolved nearby circumstellar envelopes (supp. by SPIRE)
– Surveys for fossile shells in different environments
PACS-ST Workshop, Jan. 2003 4Late type stars
Physics/chemistry of the inner parts of CSEs 2
• Molecular transitions sample different parts of CSEs because of different chemistry and excitation requirements
• CSEs provide wide ranges of density, kin. temperature and radiation environments
• Example of a 10-5 M/yr CSE: CO(1-0) samples typically a radius of 1017 cm, CO (5-4), (10-9), and (15-14) sample 61015, 21015, and 71014cm, respectively
IRAM PdB
PACS-ST Workshop, Jan. 2003 5Late type stars
Physics/chemistry of the inner parts of CSEs 2
• PACS (+SPIRE/HIFI) offer acomplete info about the physical conditions of the inner ML zones
• (e.g. important coolants CO, H2O for O-rich and CO and HCN in C-rich CSEs)
• For low resolution spectra PACS will have a much higher sensitivity than ISO, which was limited to high ML and/or very nearby objects
• HIFIs high resolution spectra will allow studies of the dynamics of these (partially ML driving) zones
Barlow et al. 1997
PACS-ST Workshop, Jan. 2003 6Late type stars
Mass loss mineralogy 1
• ISO caused a revolution in the field of astro-mineralogy of both low- and high-MLR objects
• But most of these findings were in the SWS and not the LWS range!
What to expect from PACS?
14 16 18 20 22 24
0.7
0.8
0.9
1.0
1.1
Qab
s re
sp.
F
* 2
(m)
Mg0.1
Fe0.9
O em.
g Her (1) g Her (2) V1943 Sgr
Posch et al. 2002
PACS-ST Workshop, Jan. 2003 7Late type stars
Mass loss mineralogy 2Features expected:• Forsterite (Mg2SiO4) at 69m
(sharp, dust thermometer!)• Calcite CaCO3 at 92.6m• Crystalline water-ice at 61m
(broad, high S/N needed)• 62-63m feature (Cands: Dolomite,
Ankerite, Diopsid)• CaAl12O19 feature at 78m
Most ISO observation were reallysuffering S/N problems (esp. for theinteresting low MLR-objects).The sensitivity of Herschel would be crucial but the short wave-length end of PACS is the clear limitation in this field!
Sylvester et al. 1999
Bowey et al. 2002
Kemper 2002
PACS-ST Workshop, Jan. 2003 8Late type stars
Quantitative results:Spectroscopy (for mineralogy)
• Low/intermediate-MLR objects in the solar neighbourhood:
R Cas: 1.5h for 60-130µm at S/N>20• High-MLR objects out to 1 kpc
IRC+10216 like: 6h for 60-130µm at S/N>20
PACS-ST Workshop, Jan. 2003 9Late type stars
Mass loss history 1• Currently it is not clear if AGB-ML is
mainly a continuous process or episodic on timescales of ~103 yrs as a still small number of observations suggest
• There may be interrelations between the ML history and the ML geometry
• For Herschel PACS (+SPIRE) two main strategies seem interesting: – Observations of spatially resolved
nearby circumstellar envelopes– Surveys for fossile shells in different
environments Balick et al. 2000
PACS-ST Workshop, Jan. 2003 10Late type stars
Mass loss history 2Spatially resolved nearby
detached envelopes• For the nearest objects PACS (+SPIRE)
will deliver the detailed structures of the detached envelopes (resolving timescales of less than 1000 years)
• Even very low ML episodes should be detectable (incl. ML modulations)
• At 1 kpc the largest shells are still more or less filling the FOV.
• PACS will (just) resolve some shells even at GC distances (beam at 85µm)!
Izumiura et al. 1997Olofsson et al. 2000Sahai et al. 1998
PACS-ST Workshop, Jan. 2003 11Late type stars
Quantitative results:Imaging (resolved)
• Typ. cases:
75µm, S/N>20 r t (h) t10 (h)y. DSO: R Scl (350pc) 12" 0.07 0.08
o. DSO: TT Cyg (500pc), 35" 0.7 58
• The largest objects to expect have sizes of up to 10'! (U Ant (250pc), r=200"
• SPIRE will allow for a extension towards longer wavelengths.
PACS-ST Workshop, Jan. 2003 12Late type stars
Mass loss history 3
Surveys in different environments• PACS will detect most detached
shell objects at GC distances • PACS (+SPIRE) should reach high
ML stars in the MCs • The (relatively) large FOVs will allow
mini-surveys in areas already covered by ISO at shorter wavelengths (GC, Bulge, LMC, SMC)
• Combined CC-Diagrams allow to separate cold CSEs from e.g. molecular clouds
• Such (quite expensive) mini-surveys have a multidisciplinary use!
AURA 2000Cobe 1999
0 2 4 6 8
0.0
0.5
1.0
3000
1000 500 400 300
200
100
80
70
3000/100/403000/80/40
3000/70/40
1000/600/10
75
-11
0 (
o) o
r 7
5-1
70
(x)
12-25
PACS-ST Workshop, Jan. 2003 13Late type stars
Quantitative results:Imaging pointsources 1
75µm
1kpc
110µm
1kpc
170µm
1kpc
75µm
8kpc
110µm
8kpc
170µm
8kpc
75µm
49kpc
110µm
49kpc
l. MLR
(g Her)150mJy 36mJy 3mJy 2.4mJy 0.6mJy
i. MLR
(R Cas)800mJy 360mJy 90mJy 13mJy 6mJy 1.4mJy 0.3mJy 0.2mJy
h. MLR
(IRC+10216)41Jy 8.4Jy 0.6Jy 650mJy 130mJy 10mJy 17mJy 3.5mJy
y. DSO
(R Scl)80mJy 38mJy 10mJy 2mJy 1mJy
o. DSO
(TT Cyg)15mJy 19mJy 28mJy 0.4mJy 0.5mJy
PACS-ST Workshop, Jan. 2003 14Late type stars
Quantitative results:Imaging of pointsources 2
75µm
1kpc
110µm
1kpc
170µm
1kpc
75µm
8kpc
110µm
8kpc
170µm
8kpc
75µm
49kpc
110µm
49kpc
l MLR
(g Her) 0.1h 2.3h 3h 48h
i MLR
(R Cas) 0.1h 0.6h 10h 194h
h MLR
(IRC+10216) 0.1h 0.3h 0.13h 1.5h
y DSO
(R Scl) 0.1h 0.3h 4.4h 21h
o DSO
(TT Cyg) 0.2h 175h
PACS-ST Workshop, Jan. 2003 15Late type stars
Quantitative results:Imaging of pointsources 3
• "normal" AGB stars feasible only out to GC, and at the shortest wavelengths
• High-MLR AGB stars relatively easy out to MCs in full PACS range
• Detached shell objects easy at GC and some possible at MCs at short wavelengths
• Always only in combination with ISO-Surveys!