Optical polarization in the bipolar nebula M2-9

King, David J.; Perkins, H. G.; Scarrott, S. M.; Taylor, Keith

doi:10.1093/mnras/196.1.45

Cited by 13 publications

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“…Bright condensations called "ansae" (Frank et al 1996;Garcia-Segura 1997) are seen inside the polar lobes as well, perhaps caused by shocks where fast jets strike the interiors of the polar lobes (Balick 1999;Solf 2000). The bright bipolar lobes are dusty, giving rise to extended thermal-IR emission (Smith & Gehrz 2005) and polarization in scattered light (King et al 1981;Trammell et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Kinematic Structure of H₂and [Feii] in the Bipolar Planetary Nebula M2-9

Smith

Balick

Gehrz³

2005

Astron J

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We present new high-dispersion, long-slit, infrared (IR) spectra of the double-shell bipolar planetary nebula M2-9 in the emission lines [ Fe ii] k16435 and H 2 v ¼ 1 0 S(1) k21218. H 2 spectra reveal for the first time the kinematic structure of the outer shell in M2-9. Kinematics of the inner shell, traced by [Fe ii], resemble those of optical forbidden lines like [N ii] k6583, although we note subtle differences. [Fe ii] and H 2 shells have expansion speeds roughly proportional to distance from the star (''Hubble'' flows) and share the same dynamical age of 1200-2000 yr, depending on the distance to M2-9. Thus, the inner ionized lobes and outer molecular lobes, as well as the molecular torus and ''outer loops'' measured by other observers, were all formed around the same time. Consequently, their nested structure likely arises from an excitation gradient rather than independent ejections. H 2 and [Fe ii] emission is distributed more uniformly than [N ii], and IR lines are not dominated by the moving ionization pattern like visualwavelength lines. We suggest that this is because IR lines of [Fe ii] and H 2 are excited by relatively isotropic far-UV radiation (Balmer continuum), whereas optical lines respond to a directed rotating beam of Lyman continuum. Finally, we highlight intriguing similarities between M2-9 and the Homunculus of Car, despite the different central engines powering the two nebulae.

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Section: Introductionmentioning

confidence: 99%

Kinematic Structure of H₂and [Feii] in the Bipolar Planetary Nebula M2-9

Smith

Balick

Gehrz³

2005

Astron J

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“…Throughout the electromagnetic spectrum, polarimetry (as distinct from photometry) is being transformed from a specialist occupation into a standard tool of observational astronomy, yielding valuable additional information over "scalar" photometry. At optical wavelengths, applications now range over low resolution spectropolarimetry of faint objects (Angel and Stockman 28.141.099); very high resolution spectropolarimetry of bright stars (Borra 27.116.001, Vogt et al 27.034.001, Borra et al 1981) including the Sun (Baur 1981); broad-band imaging polarimetry (Baur 1981, King et al 1981; high precision broad-band polarimetry of bright stars (Tinbergen and Zwaan 1981) and planets; phase-locked polarimetry of the Crab pulsar .…”

Section: (Iii) the Geneva Seven-colour Photometric Systemmentioning

confidence: 99%

25. Stellar Photometry and Polarimetry

Graham¹

1982

Trans. Int. Astron. Union

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Most astronomical observers at some time become involved in photometric techniques even if the participation may be limited to a rough check of the brightness of an object for measurement at the telescope. The field is in fact so broad that much of the current work is more appropriate to the reviews of other IAU Commissions and it has become accepted that Commission 25 deals mainly with those subjects which are of common practical interest to photometrists and polarimetrists around the world. We are now at the beginning of a new stage, that of observation with space telescopes and it will be important to ensure that the transition to the new techniques of measurement is a smooth one. In our review, we restrict our discussion to stellar work, leaving to other Commissions the consideration of photometry and polarimetry of stellar systems, solar system objects and gaseous nebulae. We consider recent work concerning detectors, photometric and polarimetric systems, standard stars and sequences, catalogues of new material and related items of interest to observers. The reference numbering system of Astronomy and Astrophysics Abstracts is used where possible. We shall draw attention to some important conference volumes and to some major observing projects completed during the last 3 years and finally shall look briefly towards probable developments and future prospects for the times ahead.

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A possible cause of the noncircular pattern of the linear polarization in some (bipolar) reflection nebulae

Notni

1985

Astron Nachr

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The scattering of linearly polarized light in reflection nebulae is investigatcd. 'lhe distortion of the centrosymmetric pattern of the polarization vectors is calculated; i t is found that linear polarization of the illuminating source in an optically thin nebula leads to an "elliptical" pattern. If foreward scattering angles are strongly favoured, for instance if the nebula is optically moderately thick and light from higher scattering angles is suppressed by extinction, arrays of nearly parallel polarizations may arise. In addition, circular polarisation will always occure. -Both pattern types have been observed in bipolar nebulae. We consider it probable that the investigated mechanism is, a t least in part, responsible for these patterns. Detailed modelling of concrete cases is required to finally test whether the proposed mechanism is at work.Die Streuung linear polarisierten Lichtes in Keflexionsnebeln wird nalier betrachtet. Die durch die ,,\'orpolarisation" der Lichtquelle bewirkte Abweichung der Polarisationsrichtungen des gestrcuten Lichtes von der zentralsymmetrischen Anordnung der Polarisationsvektoren wird ftir gewisse einfache Modelle berechnet. Bei optisch dtinnen Nebeln und maDiger Vorpolarisation entsteht im allgenieinen eine ,,elliptische" Anordnung der Vektoren. 1st Vorwartsstreuung stark bevorzugt, z. B. wenn groDere Streuwinkel durch Extinktion in einem optisch maL3ig dichten Nebel unterdrtickt werden, kbnnen Felder fast paralleler Polarisationsvektoren auftreten. Gleichzeitig wird stets zirkulare Polarisation erzeugt. -Beide Verteilungstypen werden insbesondere bei bipolaren Nebeln beobachtet. Bei diesen Nebeln sind die Voraussetzungen ftir die Wirkung des behandelten Mechanismus vermutlich gelegentlich erfiillt, es kann deshalb angenommen werden, daL3 die ,,Vorpolarisation" der Zentralquelle zumindest eine Teilursache fur die Pekuliaritaten der Polarisationsrichtungen ist. Eine schltissige Priifung des vorgeschlagenen Wechselwirkungsmodells sollte mit angepaoten Modellrechnungen erreichbar sein.

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Optical polarization in the bipolar nebula M2-9

Cited by 13 publications

References 0 publications

Kinematic Structure of H₂and [Feii] in the Bipolar Planetary Nebula M2-9

Kinematic Structure of H₂and [Feii] in the Bipolar Planetary Nebula M2-9

25. Stellar Photometry and Polarimetry

A possible cause of the noncircular pattern of the linear polarization in some (bipolar) reflection nebulae

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Optical polarization in the bipolar nebula M2-9

Cited by 13 publications

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Kinematic Structure of H2and [Feii] in the Bipolar Planetary Nebula M2-9

Kinematic Structure of H2and [Feii] in the Bipolar Planetary Nebula M2-9

25. Stellar Photometry and Polarimetry

A possible cause of the noncircular pattern of the linear polarization in some (bipolar) reflection nebulae

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Product

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Kinematic Structure of H₂and [Feii] in the Bipolar Planetary Nebula M2-9

Kinematic Structure of H₂and [Feii] in the Bipolar Planetary Nebula M2-9