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Article: Hubble space telescope observations of high-velocity Lyα and Hα emission from supernova remnant 1987A: The structure and development of the reverse shock

TitleHubble space telescope observations of high-velocity Lyα and Hα emission from supernova remnant 1987A: The structure and development of the reverse shock
Authors
KeywordsShock waves
Supernova remnants
Supernovae: individual (SN 1987A)
Issue Date2003
PublisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205
Citation
Astrophysical Journal Letters, 2003, v. 593 n. 2 I, p. 809-830 How to Cite?
AbstractWe present two-dimensional line profiles of high-velocity (∼±12,000 km s -1) Lyα and Hα emission from supernova remnant 1987A obtained with the Space Telescope Imaging Spectrograph between 1997 September and 2001 September (days 3869-5327 after the explosion). This emission comes from hydrogen in the debris that is excited and ionized as it passes through the remnant's reverse shock. We use these profiles to measure the geometry and development of the reverse-shock surface. The observed emission is confined within ∼±30° about the remnant's equatorial plane. At the equator, the reverse shock has a radius of ∼75% of the distance to the equatorial ring. We detect marginal differences (6% ± 3%) between the location of the reverse-shock front in the northeast and southwest parts of the remnant. The radius of the reverse shock surface increases for latitudes above the equator, a geometry consistent with a model in which the supernova debris expands into a bipolar nebula. Assuming that the outer supernova debris has a power-law density distribution, we can infer from the reverse-shock emission light curve an expansion rate (in the northeast part of the remnant) of 3700 ± 900 km s -1, consistent with the expansion velocities determined from observations in radio (Manchester et al.) and X-ray (Park et al.; Michael et al.) wavelengths. However, our most recent observation (at day 5327) suggests that the rate of increase of mass flux across the northeast sector of the reverse shock has accelerated, perhaps because of deceleration of the reverse shock caused by the arrival of a reflected shock created when the blast wave struck the inner ring. Resonant scattering within the supernova debris causes Lyα photons created at the reverse shock to be directed preferentially outward, resulting in a factor of ∼5 difference in the observed brightness of the reverse shock in Lyαa between the near and far sides of the remnant. Accounting for this effect, we compare the observed reverse-shock Lyα and Hα fluxes to infer the amount of interstellar extinction by dust as E(B - V) = 0.17 ± 0.01 mag. We also notice extinction by dust in the equatorial ring with E(B - V) ≈ 0.02-0.08 mag, which implies dust-to-gas ratios similar to that of the LMC. Since Hα photons are optically thin to scattering, the observed asymmetry in brightness of Hα from the near and far sides of the remnant represents a real asymmetry in the mass flux through the reverse shock of ∼30%. We discuss future observational strategies that will permit us to further investigate the reverse-shock dynamics and resonant scattering of the Lyα line and to constrain better the extinction by dust within and in front of the remnant.
Persistent Identifierhttp://hdl.handle.net/10722/43419
ISSN
2015 Impact Factor: 5.487
2015 SCImago Journal Rankings: 3.369
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorMichael, Een_HK
dc.contributor.authorMcCray, Ren_HK
dc.contributor.authorChevalier, Ren_HK
dc.contributor.authorFilippenko, AVen_HK
dc.contributor.authorLundqvist, Pen_HK
dc.contributor.authorChallis, Pen_HK
dc.contributor.authorSugerman, Ben_HK
dc.contributor.authorLawrence, Sen_HK
dc.contributor.authorPun, CSJen_HK
dc.contributor.authorGarnavich, Pen_HK
dc.contributor.authorKirshner, Ren_HK
dc.contributor.authorCrotts, Aen_HK
dc.contributor.authorFransson, Cen_HK
dc.contributor.authorLi, Wen_HK
dc.contributor.authorPanagia, Nen_HK
dc.contributor.authorPhillips, Men_HK
dc.contributor.authorSchmidt, Ben_HK
dc.contributor.authorSonneborn, Gen_HK
dc.contributor.authorSuntzeff, Nen_HK
dc.contributor.authorWang, Len_HK
dc.contributor.authorWheeler, JCen_HK
dc.date.accessioned2007-03-23T04:45:20Z-
dc.date.available2007-03-23T04:45:20Z-
dc.date.issued2003en_HK
dc.identifier.citationAstrophysical Journal Letters, 2003, v. 593 n. 2 I, p. 809-830en_HK
dc.identifier.issn2041-8205en_HK
dc.identifier.urihttp://hdl.handle.net/10722/43419-
dc.description.abstractWe present two-dimensional line profiles of high-velocity (∼±12,000 km s -1) Lyα and Hα emission from supernova remnant 1987A obtained with the Space Telescope Imaging Spectrograph between 1997 September and 2001 September (days 3869-5327 after the explosion). This emission comes from hydrogen in the debris that is excited and ionized as it passes through the remnant's reverse shock. We use these profiles to measure the geometry and development of the reverse-shock surface. The observed emission is confined within ∼±30° about the remnant's equatorial plane. At the equator, the reverse shock has a radius of ∼75% of the distance to the equatorial ring. We detect marginal differences (6% ± 3%) between the location of the reverse-shock front in the northeast and southwest parts of the remnant. The radius of the reverse shock surface increases for latitudes above the equator, a geometry consistent with a model in which the supernova debris expands into a bipolar nebula. Assuming that the outer supernova debris has a power-law density distribution, we can infer from the reverse-shock emission light curve an expansion rate (in the northeast part of the remnant) of 3700 ± 900 km s -1, consistent with the expansion velocities determined from observations in radio (Manchester et al.) and X-ray (Park et al.; Michael et al.) wavelengths. However, our most recent observation (at day 5327) suggests that the rate of increase of mass flux across the northeast sector of the reverse shock has accelerated, perhaps because of deceleration of the reverse shock caused by the arrival of a reflected shock created when the blast wave struck the inner ring. Resonant scattering within the supernova debris causes Lyα photons created at the reverse shock to be directed preferentially outward, resulting in a factor of ∼5 difference in the observed brightness of the reverse shock in Lyαa between the near and far sides of the remnant. Accounting for this effect, we compare the observed reverse-shock Lyα and Hα fluxes to infer the amount of interstellar extinction by dust as E(B - V) = 0.17 ± 0.01 mag. We also notice extinction by dust in the equatorial ring with E(B - V) ≈ 0.02-0.08 mag, which implies dust-to-gas ratios similar to that of the LMC. Since Hα photons are optically thin to scattering, the observed asymmetry in brightness of Hα from the near and far sides of the remnant represents a real asymmetry in the mass flux through the reverse shock of ∼30%. We discuss future observational strategies that will permit us to further investigate the reverse-shock dynamics and resonant scattering of the Lyα line and to constrain better the extinction by dust within and in front of the remnant.en_HK
dc.format.extent1540493 bytes-
dc.format.extent26624 bytes-
dc.format.mimetypeapplication/pdf-
dc.format.mimetypeapplication/msword-
dc.languageengen_HK
dc.publisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205en_HK
dc.relation.ispartofAstrophysical Journal Lettersen_HK
dc.rightsThe Astrophysical Journal. Copyright © University of Chicago Press.en_HK
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subjectShock wavesen_HK
dc.subjectSupernova remnantsen_HK
dc.subjectSupernovae: individual (SN 1987A)en_HK
dc.titleHubble space telescope observations of high-velocity Lyα and Hα emission from supernova remnant 1987A: The structure and development of the reverse shocken_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0004-637X&volume=593&issue=2 pt 1&spage=809&epage=830&date=2003&atitle=Hubble+Space+Telescope+Observations+of+High-Velocity+Ly+and+Hα+Emission+from+Supernova+Remnant+1987A:+The+Structure+and+Development+of+the+Reverse+Shocken_HK
dc.identifier.emailPun, CSJ: jcspun@hkucc.hku.hken_HK
dc.identifier.authorityPun, CSJ=rp00772en_HK
dc.description.naturepublished_or_final_versionen_HK
dc.identifier.doi10.1086/376725en_HK
dc.identifier.scopuseid_2-s2.0-18744419711en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-18744419711&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume593en_HK
dc.identifier.issue2 Ien_HK
dc.identifier.spage809en_HK
dc.identifier.epage830en_HK
dc.identifier.isiWOS:000184823400017-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridMichael, E=7004899413en_HK
dc.identifier.scopusauthoridMcCray, R=35954431900en_HK
dc.identifier.scopusauthoridChevalier, R=7101871369en_HK
dc.identifier.scopusauthoridFilippenko, AV=34568722000en_HK
dc.identifier.scopusauthoridLundqvist, P=7004499555en_HK
dc.identifier.scopusauthoridChallis, P=7004555495en_HK
dc.identifier.scopusauthoridSugerman, B=9433763600en_HK
dc.identifier.scopusauthoridLawrence, S=7202646485en_HK
dc.identifier.scopusauthoridPun, CSJ=7003931846en_HK
dc.identifier.scopusauthoridGarnavich, P=7006524172en_HK
dc.identifier.scopusauthoridKirshner, R=35277140000en_HK
dc.identifier.scopusauthoridCrotts, A=35241689000en_HK
dc.identifier.scopusauthoridFransson, C=7004051800en_HK
dc.identifier.scopusauthoridLi, W=37060700300en_HK
dc.identifier.scopusauthoridPanagia, N=35400629400en_HK
dc.identifier.scopusauthoridPhillips, M=7402770160en_HK
dc.identifier.scopusauthoridSchmidt, B=7402828523en_HK
dc.identifier.scopusauthoridSonneborn, G=7006137500en_HK
dc.identifier.scopusauthoridSuntzeff, N=7006255654en_HK
dc.identifier.scopusauthoridWang, L=45361626600en_HK
dc.identifier.scopusauthoridWheeler, JC=7403110438en_HK

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