distances to pne using angular expansion parallax lizette guzman-ramirez (jbca, university of...
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![Page 1: Distances to PNe using angular expansion parallax Lizette Guzman-Ramirez (JBCA, University of Manchester) Yolanda Gomez and Laurent Loinard (CRyA, UNAM,](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d625503460f94a446de/html5/thumbnails/1.jpg)
Distances to PNe using angular
expansion parallaxLizette Guzman-Ramirez
(JBCA, University of Manchester)
Yolanda Gomez and Laurent Loinard
(CRyA, UNAM, Mexico)
41st YERAC
University of Manchester/Jodrell Bank Observatory,
18-20 July 2011
![Page 2: Distances to PNe using angular expansion parallax Lizette Guzman-Ramirez (JBCA, University of Manchester) Yolanda Gomez and Laurent Loinard (CRyA, UNAM,](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d625503460f94a446de/html5/thumbnails/2.jpg)
Why distances are important?
• Essential parameter for studying the stellar and nebular parameters as well as the evolution of the central star.
• While the total number of PNe in the Milky Way has been estimated to be somewhere between 5000 and 25,000, less than 50 have distances with reasonable accuracy.
• Used to measure the rotational curve in other galaxies, dark matter halos and using the PNLF estimate the distance to this galaxies.
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PNe
• M2-43 [WC8]– Distance estimations 1.4 kpc (Cahn et al. 1992) to
4.45 kpc (Van de Steen et al. 1994b)
• IC 418– Distances estimations 0.36 kpc (Acker et al. 1978)
to 5.74 kpc (Phillips et al. 1984)
• NGC 6881– Distance estimations 1.5 kpc (Cahn et al. 1984) to
6.4 kpc (Zhang et al. 1995)
![Page 5: Distances to PNe using angular expansion parallax Lizette Guzman-Ramirez (JBCA, University of Manchester) Yolanda Gomez and Laurent Loinard (CRyA, UNAM,](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d625503460f94a446de/html5/thumbnails/5.jpg)
Angular Expansion in Radio• Masson (1986), was the first person to use this technique.
• Observed NGC 7027 in two epochs with a 2.8 years gap.
• Because you are trying to observe very small changes in the nebula, this technique requires very high resolution data.
• Interferometry is the way to go.
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M2-43
• VLA-A, 1995.65 & 1999.72
• At 8Ghz (3.6 cm)
• Angular resolution of 0.3”
t=4.07 yr
Model
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IC 418
• VLA-B, 1986.49 & 2007.85
• At 5GHz (6 cm)
• Angular resolution of 3”
t=21.36 yr
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NGC 6881
• VLA-A, 1984.99 & 1994.24
• At 4.8GHz (6 cm)
• Angular resolution of 0.8”
t=9.25 yr
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Angular Expansiond/dt = /t,
where is the size of the nebula (“) and t is the difference between the two epochs.
• M2-43 d/dt = 0.61 +/- 0.09 mas/yr.• IC418 d/dt = 5.80 +/- 1.50 mas/yr.• NGC 6881 d/dt = 2.10 +/- 0.70 mas/yr.
D = 211(vexp / d/dt ),• M2-43 D = 6.9 +/- 1.5 kpc.• IC 418 D = 1.3 +/- 0.4 kpc.• NGC 6881 D = 1.6 +/- 0.5 kpc.
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Important Parameters
M2-43• Ionised MassMion = 0.03 M
• Electronic Density ne = 1.1 x 105 cm-3 • Emission Measure EM = 4 x 108 cm-6pc• Kinematic AgeT = 500 yr
IC 418• Ionised MassMion = 8.7 M
• Electronic Density ne = 6.2 x 103 cm-3 • Emission Measure EM = 5 x 106 cm-6pc• Kinematic AgeT = 1200 yr
NGC 6881• Ionised MassMion = 0.002 M
• Electronic Density ne = 5 x 104 cm-3
• Emission Measure EM = 28 x 106 cm-6pc• Kinematic AgeT = 350 yr
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Name D (kpc) ReferenceBD+303639 1.69 +/- 1.30 2.80 +/- 3 Masson (1989)BD+303639 1.73 +/- 0.51 2.68 +/- 0.81 Hajian et al. (1993)NGC 3242 13.2 +/- 4.7 0.42 +/- 0.16 Hajian et al. (1995)NGC 6302 1.7 +/- 0.3 1.60 +/- 0.6 Gómez et al. (1993)NGC 6210 3.10 +/- 0.42 1.57 +/- 0.40 Hajian et al. (1995)NGC 6572 2.51 +/- 0.76 1.49 +/- 0.62 Hajian et al. (1995)NGC 7027 4.7 +/- 7 0.94 +/- 0.2 Masson (1986)NGC 7662 5.6 +/- 5 0.79 +/- 0.75 Hajian y Terzian (1996)VY 2-2 1.13 +/- 0.12 3.60 +/- 0.4 Christianto y Seaquist (1998)M2-43 0.61 +/- 0.09 6.9 +/- 1.5 Guzman et al (2006)IC 418 5.8 +/- 1.5 1.3 +/- 0.4 Guzman et al (2009)NGC 6881 2.1 +/- 0.7 1.6 +/- 0.5 Guzman et al (2011)
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Conclusions and Future Work
• Distances are important!• Angular expansion technique give us
reliable distances with a good accuracy. • Proposal for eMerlin for a few more
objects that have already been observed so we only need a second epoch.
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Thank you!
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Radial velocity• M2-43, radial velocity
of 111 +/- 40 km/s (Schneider et al., 1983),
• Galactic model from Brand & Blitz (1993).