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

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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

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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!