![Page 1: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/1.jpg)
ANGULAR EXPANSION IN PLANETARY
NEBULAE FROM RADIO INTERFEROMETRIC DATA
Yolanda Gómez
Centro de Radioastronomía y Astrofísica, UNAM
México
![Page 2: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/2.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
Colaborators
Lizette Guzmán (CRyA, UNAM, México)Luis F. Rodríguez (CRyA, UNAM, México)
![Page 3: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/3.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
Angular expansion techniqueA geometrical method in which we substract two
images, taken over a period of a few years, to estimate the angular expansion rate of the nebula,
First applied by Masson (1986) to radio interferometric data to estimate distances to PNe.
1
//211 exp
yrmasskm
VpcD
v
D=v/D
![Page 4: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/4.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
Some examples
This technique has been applied with success to several PNe: e.g. NGC6302 (Gómez et al. 1993) , NGC6572 (Hajian
et al. 1995) , Vy 2-2 (Christianto & Seaquist 1998).
For PNe with distances > 1 kpc the expected angular expansion rate is < 2 mas/yr.
NGC 7027
yrmas /7.4
yrt 8.2
skmV /21exp
kpcD 2.094.0
(Masson 1986; 1989)
![Page 5: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/5.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
Planetary Nebula M 2-43
This is the largest distance for a PN measured, up to now, with the angular expansion technique.
yrmas /61.0
yrt 4
kpcD 5.19.6
(Guzmán, Gómez & Rodríguez 2006)
See poster by Guzmán et al.
skmV /20exp
VLA 3.6 cm
1999.72–1995.651999.72+1995.65
![Page 6: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/6.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
Other application for the angular expansion technique
![Page 7: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/7.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
The “Saturn Nebula” NGC 7009 The ansae (handles) are present in PNe with bipolar, rotating, episodic jets ( BRETS; e.g. López et al. 1995) and fast, low ionization emission regions (FLIERS; Balick et al. 1993).
In NGC 7009 the ansae are moving at about 100 km/s in the plane of the sky, relative to the nucleus (Reay & Atheton 1985; Balick et al. 1987).
The ansae are possibly the termination points of the jets (Balick et al. 1987; López et al. 2000; Steffen et al. 2001).
ansae
HST
Red [NII]; green [OIII]; blue [He II]
![Page 8: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/8.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
Proper motions of ansae
NGC 7009 Few measurements of proper motions of ansae: KjPn 8 (Meaburn
1997), Hen 2-90 (Sahai et al. 2002), NGC7009 (Fernández et al. 2004).
NGC 7009: From photographic plates a PM of 16 3 mas/yr (Liller 1965)
From HST images a PM for the eastern ansa of 28 8 mas/yr (Fernández et al. 2004) is derived.
HST images of the east ansa (Fernández, Monteiro & Schwarz 2004)
![Page 9: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/9.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
• Archive VLA data for NGC 7009 at 3.6 cm in two epochs: 1989.24 and 1997.33
Observations
NGC 7009yrt 09.8
VLA
Applying the angular expansion technique to NGC 7009 to measure proper motions of the ansae at radio.
VLA 3.6 cm
![Page 10: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/10.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
Western
Eastern
23 +/- 6 mas/yr
34 +/- 10 mas/yr
Ansae proper motions
(Rodríguez & Gómez 2007, RevMexAA, 43, 173)
![Page 11: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/11.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
Derived parameters for the ansae NGC 7009
• Assuming D= 860 +/- 340 pc, the velocities of the ansae in the plane of the sky are:
EAST ansa 100 +/- 50 km/s
WEST ansa 140 +/- 70 km/s• If the ansae are moving ballistically the estimated
age is:
~300 years if they originated from the main body
~850 years if they originated from the central star.
![Page 12: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/12.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
Upper limit to the expansion
Difference image
D 700 pc
Lower limit consistent with the average of 14 available values (Acker et al. 1992; Fernández et al.
2004), 860 +/- 340 pc.
The flux density of the main body remains constant.
The flux density of the jets decreased in 30%. With an electron density 1000 – 4000 cm-3 (Bohigas et al. 1994; Goncalves et al. 2003) the recombination timescales are between 30 to 120 yrs.
![Page 13: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/13.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
Conclusions Interferometric data taken with a few years of
separation can reveal the angular expansion of the nebula and it is possible to estimate its distance (e.g. M 2-43; Guzmán et al. 2006).
This is the first time that proper motions of ansae in PNe are determined with radio observations (NGC 7009; Rodríguez & Gómez 2007).
![Page 14: ANGULAR EXPANSION IN PLANETARY NEBULAE FROM RADIO INTERFEROMETRIC DATA](https://reader035.vdocuments.site/reader035/viewer/2022062422/56813c78550346895da60ebf/html5/thumbnails/14.jpg)
Asymmetrical Planetary Nebulae IV, La Palma, España
Thank you