RAMAN-SCATTERED He II λ6545 IN THE YOUNG AND COMPACT PLANETARY NEBULA NGC 6790

Kang, Eun-Ha; Lee, Heewon; Lee, Byeong‐Cheol

doi:10.1088/0004-637x/695/1/542

Cited by 13 publications

(14 citation statements)

References 30 publications

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“…Shore et al 2014, and references therein). The SySt classification is additionally supported by the fact that thus far only Raman scattered He ii lines have been observed in young PNe (Pequignot et al 1997;Lee et al 2001Lee et al , 2006Kang et al 2009), which we do not detect in our spectra, while the 6825Å line is one of the strongest emission lines in the optical range. Since SMP LMC 88 shows a resolved nebula (e.g.…”

Section: Symbiotic Classificationsupporting

confidence: 78%

A D’-type symbiotic binary in the planetary nebula SMP LMC 88

Iłkiewicz

Mikołajewska

Miszalski

et al. 2018

Monthly Notices of the Royal Astronomical Society

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SMP LMC 88 is one of the planetary nebulae (PN) in the Large Magellanic Cloud. We identify in its spectrum Raman scattered O vi lines at 6825 and 7083Å. This unambiguously classifies the central object of the nebula as a symbiotic star (SySt). We identified the cold component to be a K-type giant, making this the first D'-type (yellow) SySt discovered outside the Galaxy. The photometric variability in SMP LMC 88 resembles the the orbital variability of Galactic D'-type SySt with its low amplitude and sinusoidal lightcurve shape. The SySt classification is also supported by the He I diagnostic diagram.

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Section: Symbiotic Classificationsupporting

confidence: 78%

A D’-type symbiotic binary in the planetary nebula SMP LMC 88

Iłkiewicz

Mikołajewska

Miszalski

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…Since then, O VI Raman scattering has been described in many papers, and due to other resonances such as the He II λ1025 line, see Sekeráš & Skopal (2015) and references therein. Furthermore, Raman scattered He II features were identified in Planetary Nebulae (PNe) by Pequignot et al (1997) and these have since been identified in other PNe (Groves et al 2002;Lee et al 2006;Kang et al 2009). O VI Raman scattering was also discovered in the Planetary Nebula NGC 6302 by Groves et al (2002).…”

Section: Raman Scatteringmentioning

confidence: 99%

The Discovery of Raman Scattering in H Ii Regions

Dopita

Nicholls

Sutherland

et al. 2016

ApJL

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We report here on the discovery of faint extended wings of Hα observed out to an apparent velocity of ∼ 7600 km s −1 in the Orion Nebula (M42) and in five H II regions in the Large and the Small Magellanic Clouds. We show that, these wings are caused by Raman scattering of both the O I and Si II resonance lines and stellar continuum UV photons with H I followed by radiative decay to the H I n = 2 level. The broad wings also seen in Hβ and in Hγ result from Raman scattering of the UV continuum in the H I n = 4 and n = 5 levels respectively.The Raman scattering fluorescence is correlated with the intensity of the narrow permitted lines of O I and Si II. In the case of Si II, this is explained by radiative pumping of the same 1023.7Å resonance line involved in the Raman scattering by the Lyβ radiation field. The subsequent radiative cascade produces enhanced Si II λλ5978.9, 6347.1 and 6371.4Å permitted transitions. Finally we show that in O I, radiative pumping of the 1025.76Å resonance line by the Lyman series radiation field is also the cause of the enhancement in the permitted lines of this species lying near Hα in wavelength, but here the process is a little more complex. We argue that all these processes are active in the zone of the H II region near the ionisation front.

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“…A number of young planetary nebulae are known to exhibit Raman scattered He II features (e.g. Pequignot et al [2], Groves et al [3], Kang et al [4]). …”

Section: Introductionmentioning

confidence: 99%

Profile disparity of Raman-scattered O VI in symbiotic stars

Lee

2016

J. Phys.: Conf. Ser.

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Abstract. Symbiotic stars are wide binary systems consisting of a hot compact star (usually a white dwarf) and a mass losing giant. Symbiotic activities are believed to occur through gravitational capture of a fraction of the slow stellar wind from the giant. Raman scattered features of O VI resonance doublet 1032 and 1038 appearing at around 6825Å and 7082Å are a unique spectroscopic diagnostic tool to probe the mass transfer process in symbiotic stars. The Raman O VI features often exhibit multiple peak structures and in many cases the blue peak of 7082 features is relatively more suppressed than that of 6825 features. We propose that the disparity of the two profiles is attributed to the local variation of optical depths of O VI, implying that the accretion flow is convergent in the red emission region and divergent in the blue emission region. It is argued in this presentation that Raman scattering by atomic hydrogen is a natural mirror to provide an edge-on view of the accretion disk and a lateral view of the bipolar outflow in symbiotic stars. We discuss the spectropolarimetric implications of this interpretation. IntroductionSymbiotic stars are binary systems consisting of a hot white dwarf and a mass losing giant. They exhibit prominent emission lines with a broad range of ionization and excitation. The symbiotic activities are attributed to the mass transfer processes involving a gravitational capture of some fraction of the slow stellar wind from the giant component. One unique aspect of the spectra of symbiotic stars is the presence of the spectral features formed through Raman scattering of far UV radiation more energetic than Lyα by atomic hydrogen.The Raman scattering process is the combination of the annihilation of the incident radiation with the excitation of the hydrogen atom and the creation of the Raman scattered radiation accompanied by the de-excitation of the hydrogen atom into the 2s state. For example, an O VIλ1032 photon is Raman scattered to appear at 6825Å, and in a similar way an O VIλ1038 is Raman scattered to be emergent at 7082Å. These two Raman O VI features at 6825Å and 7082Å are observed in about half of symbiotic stars and were first identified by Schmid [1]. Raman scattered line features observed thus far include He IIλλ 1025, 972 and 949, Ne VIIλ973 and C IIλλ1036 and 1037.The scattering cross section for resonance doublet O VIλλ 1032 and 1038 is of order 10 −22 cm 2 . The cross section for O VIλ1032 is larger than for O VIλ1038, which results in about 5-10 times stronger Raman O VI feature at 6825Åthan 7082Å. The small cross section for these Raman features implies that the operation of Raman scattering requires a very special condition of the existence of a highly thick H I region in the vicinity of a strong far UV source.

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RAMAN-SCATTERED He II λ6545 IN THE YOUNG AND COMPACT PLANETARY NEBULA NGC 6790

Cited by 13 publications

References 30 publications

A D’-type symbiotic binary in the planetary nebula SMP LMC 88

A D’-type symbiotic binary in the planetary nebula SMP LMC 88

The Discovery of Raman Scattering in H Ii Regions

Profile disparity of Raman-scattered O VI in symbiotic stars

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