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The emission nebula Sh 2-174: a radio investigation of the surrounding region

Par Conseil national de recherches du Canada

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DOITrouver le DOI : https://doi.org/10.1088/0004-637X/799/2/198
AuteurRechercher : 1; Rechercher : 1; Rechercher : 1; Rechercher : ; Rechercher : 1
Affiliation
  1. Conseil national de recherches du Canada. Herzberg en astronomie et en astrophysique
FormatTexte, Article
SujetISM: magnetic fields; ISM: structure; planetary nebulae: individual (Sh 2-174); stars: individual (GD 561); stars: kinematics and dynamics; techniques: polarimetric
Résumé
Sh 2-174 is believed to be either a planetary nebula (PN) or ionized, ambient interstellar medium (ISM). We present in this paper 1420 MHz polarization, 1420 MHz total intensity (Stokes-I), and neutral hydrogen (H I) images of the region around Sh 2-174. The radio images address not only the nature of the object, but also the history of the relationship between Sh 2-174 and its surrounding environment. The H I images show that Sh 2-174 sits presently at the center of a ~1fdg2 × ~0fdg4 cloud (with peak hydrogen density n H = 4 ± 2 cm–3). The Stokes-I image shows thermal-emission peaks (with electron densities ne = 11 ± 3 cm–3) coincident with the R-band optical nebula, as well as low-surface-brightness emission from an ionized "halo" around Sh 2-174 and from an ionized "plateau" extending southeast from the cloud. The polarization images reveal Faraday-rotation structures along the projected trajectory of Sh 2-174, including a high-contrast structure with "arms" that run precisely along the eastern edge of the H I cloud and a wide central region that merges with the downstream edge of Sh 2-174. The high-contrast structure is consistent with an ionized tail that has both early-epoch (before Sh 2-174 entered the cloud) and present-epoch (after Sh 2-174 entered the cloud) components. Furthermore, our rotation-measure analysis indicates that the ISM magnetic field is deflected at the leading edge of Sh 2-174. The downstream tail and upstream field deflection point to a PN-ISM interaction. Our estimated space velocity for the host white dwarf (GD 561) demonstrates that Sh 2-174 entered the cloud ~27,000 yr ago, and gives a PN-ISM interaction timescale lesssim 2.0 × 105 yr. We estimate an ambient magnetic field in the cloud of 11 ± 3 μG.
Date de publication
Maison d’éditionAmerican Astronomical Society
IOP Publishing
Dans
  • The Astrophysical Journal 799, nº 2, 198.
Langueanglais
Publications évaluées par des pairsOui
Numéro NPARC23001647
Exporter la noticeExporter en format RIS
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Identificateur de l’enregistrement624e2522-142a-4d98-b0cf-b930d5fc0e07
Enregistrement créé2017-03-14
Enregistrement modifié2020-05-30
Date de modification :