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Maser emission in Planetary Nebulae
Yolanda GÑmez
Centro de RadioastronomÌa y AstrofÌsica, UNAM, MÈxico.

Alice Springs , Australia, 2007


Collaborators:
· · · · · · · · · · · D. Tafoya (CRyA, UNAM) L. Uscanga ( CRyA, UNAM) N. Patel (CfA, USA) G. Anglada (IAA, Spain) J. M. Torrelles (IEEC, Spain) L. F. Miranda (IAA, Spain) J. F. GÑmez (IAA, Spain) I. De Gregorio-Monsalvo (ESO) O. SuÀrez (LAEFF-INTA, Spain) J.I. Nakashima (Taiwan) S. Deguchi (Japan)


OUTLINE
Introduction Young PNe with OH and H2O masers K 3-35 and IRAS 17347-3139 Kinematics of H2O masers in K 3-35 Equatorial magnetic field in K 3-35 ? Summary


Introduction
Planetary nebulae represent a final stage of stellar evolution
ter completion of H and He core Af burning, the star evolves to the AGB. he mass loss rate in the AGB could T be 0-6 Msunyear-1. 1 velope of gas and dust. The star no En longer detectable in the optical . the top of the AGB phase the At gravity contracts the core. Ionization begins and a PN is formed.


Introduction
Planetary nebulae represent a final stage of stellar evolution
ter completion of H and He core Af burning, the star evolves to the AGB. he mass loss rate in the AGB could T be 0-6 Msunyear-1. 1 velope of gas and dust. The star no En longer detectable in the optical . the top of the AGB phase the At gravity contracts the core. Ionization begins and a PN is formed. Lifetime 104 years


· Most of the PNe (~75%) show asymmetrical morphologies


When are the asymmetric structures in PNe formed?


AGB winds

spherical (?)

Transition time scale ~1000 years (Kwok 1993

)

PNe

asymmetric


OH, H2O and SiO masers can be detected in AGB stars


VXSgr Masers stratified in the envelope due to chemical and excitation conditions (Reid
3 x 1016cm

3x1

015c

m

& Moran 1981; Elitzur 1992)

Chapman & Cohen 1986, MNRAS, 220, 513

3 x 1014cm

If we consider an isotropic shell expanding at ~10 km/s, then when the slow wind stops, masers will "disappear" in a time scale of ~10, 100 and 1000 years for the SiO, H 2O and OH, respectively (GÑmez, Moran & RodrÌguez 1990).


IRAS 16342-3814
(Sahai et al. 1999)

OH 37.1- 0.8

VLBA OH 1612 MHz

Proto PNe

(GÑmez et al. 1999)

W43A
(Imai et al. 2002)


We will talk of young planetary nebulae (where ionization is already present), but that retain OH and H2O maser emission.


Several surveys have been carried out to search for OH masers in PNe (e.g. Johansson et
Payne et al. 1988
OH

al. 1977; Caswell et al. 1981; Bowers & Knapp 1989; Zijlstra et al. 1989; Sevenster & Chapman 2001).
Planetary Nebula NGC 6302

GÑmez et al. 1989

·The presence of OH maser suggests that a neutral envelope is still present in the PN, implying that it is young.


OH maser emission in PNe
· M 1-92 (LÈpine & Rieu 197 · Vy 2-2 (Davis et al. 1979) · NGC 6302 (Payne et al.
1988) 4)

· IC 4997 · K 3-35 (

(Tamura et al. 1989) Engels et al. 1985)

H2O maser emission
Miranda et al. 2001 De Gregorio-Monsalvo et al. 2004.

· · · · · · · · · ·

OH 349.36-020 OH 0.9+1.3 IRAS 7207-2855 PK 356+2.1 IRAS 17347-3139 IRAS 17371-2747 IRAS 17375-2759 IRAS 17375-3000 IRAS 17443-2949 IRAS 17580-3111

(Zijlstra et al. 1989)


NGC 6302

· Recently, SuÀrez et al. 2007, detected two new PNe with H2O maser emission, using the Robledo de Chavela antenna. · VLA observations are in progress.

SuÀrez, GÑmez, Morata 2007, A&A, in press.


K 3-35 and IRAS 17347-3139


Miranda, et al. 2001

K 3-35 the first PN with H2O maser.
Is

an emission nebula with bipolar jets (Aaquist & Kwok 1989; Aaqu
1993; Miranda et al. 2000; Miranda et al. 2001)

ist

r B

(Engels et al.1985; Dayal & Bieging 1996; Huggins et al. 2005; Tafoya et al. 2007 ) VLA, 3.6 cm =

oad CO lines

H


CO+(1-0)

(Tafoya et al. 2007)

OH and H2O masers were detected but the association was unclear ( Engels
et al. 1985; Aaquist 1993)

iran M

Tafoya, et al. 2007

da et al. 2001 using the VLA confirmed the association of OH and H2O maser emission with K 3-35.


(Miranda, GÑmez, Anglada & Torrelles 2001, Nature, 414, 284)


Water masers in K 3-35 are located at a projected distance of 85 AU from the peak continuum emission suggesting the presence of an equatorial disk.
V(LSR)= 24 +/- 2 km/s

Miranda et al. 2001

The velocities of H 2O masers are blueshifted with respect to the systemic velocity.


EXPANDING AND ROTATING DISK
K 3-35

Miranda et al. 2000

Uscanga et al. 2007


Kinematics of H2O masers in IRAS 17347-3139


IRAS 17347-3139 the second PN with H2O maser emission.
MSX & IRAS 2MASS

· Strong IRAS source. The SED peaks at 60 µm (GÑmez et al. 2005). · Estimated distance 0.6-8 kpc (GÑme
et al 2005)
ATCA

z

Optical

· OH 1612 MHz
2007, see poster)

(Zijlstra et al. 1989; Tafoya

· A search for H2O masers, with the 70 m antenna of Robledo de Chavela, in 27 sources, we detected only IRAS 173473139 (De Gregorio-Monsalvo et al. 2004).
VLA H2O masers


IRAS 17347-3139

VLA 1.3 cm continuum Tafoya, et al 2007

· A kinematic model suggests that the water masers could be tracing one edge of an equatorial disk (Uscanga et al. 2007).

IRAS 17347-3139

NIR Keck image. SÀnchez Contreras et al. 2006.


Equatorial magnetic field in K3-35?


Evidence of magnetic fields in PNe
Circumstellar envelopes
Magnetic fields of ~ mG at distances from 100 -1000 AU · OH 0.9+1.3 by OH circular polarization (Zijlstra et al. 1989;
Szymczak & GÈrard 2004)

· NGC 7027, NGC 6537, and NGC 6302 by polarimetry of magnetically aligned dust grains (Greaves 2002; Sabin et al. 2007). · K 3-35 by OH circular polarization (Miranda et al. 2001, GÑmez et
al. 2005)

Central Stars
Magnetic fields of kG from the central stars ·NGC 1360, LSS 1362 by optical spectro-polarimetry (Jordan et
al. 2005)


Observations
· VLA observations of the 1612, 1665, 1667 & 1720 MHz OH maser emission from K3-35 · Spatial resolution ~1" · Relative positional accuracy between masers of ~mas · Spectral resolution
Very Large Array (VLA), USA..

~0.14 km/s (1665 & 1667 MHz) ~0.53 km/s (1612 & 1720 MHz).


K 3-35
1665 MHz 1612 MHz

1667 MHz

1720 MHz

The strong levels of circular polarization in the OH 1665 MHz >50% suggest the presence of a magnetic field in K 3 -35. GÑmez et al. 2007


K 3-35

This is the only one PN where the OH 1720 MHz transition is observed. Its position is coincident with the radio continuum peak.


OH 1720 MHz

Stokes V

If at least one Zeeman pair is present in the 1665 and 1720 MHz transitions, we can estimate the magnetic field.
1665 MHz: C= 3.27

Vobs Blos dI/d z C H G

-1

(Crutcher et al. 1993; Yusef -Zadeh et al. 1996)

1720MHz: C= 0.65

Blos~ 0.14 mG
Radius=250 AU

Blos~ 0.75 mG
Radius=120 AU


Summary
The presence of H2O and OH masers in PNe suggests that these objects are very young in them. K 3-35 and IRAS 17347-3139 are until now the only PNe with H2O maser emission. K 3-35 is the only one PN where the OH 1720 MHz transition is detected. Kinematic is consistent with masers located in rings but modeling uncertain. There is evidence of mG magnetic fields in K 3-35.


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