Kinematic structure of H 2 and [Fe II] in the bipolar planetary nebula M2-9

Nathan Smith, Bruce Balick, Robert D. Gehrz

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

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] λ16435 and H 2 v = 1-0 S(1) λ21218. 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] λ6583, 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 visual-wavelength 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 η Car, despite the different central engines powering the two nebulae.

Original languageEnglish (US)
Pages (from-to)853-861
Number of pages9
JournalAstronomical Journal
Volume130
Issue number2
DOIs
StatePublished - Aug 2005
Externally publishedYes

Fingerprint

planetary nebulae
lobes
kinematics
shell
continuums
nebulae
ejection
slits
engines
infrared spectra
stars
ionization
gradients
expansion
radiation
wavelengths
excitation
automobile
engine
wavelength

Keywords

  • Circumstellar matter
  • Planetary nebulae: general
  • Planetary nebulae: individual (M2-9)
  • Stars: evolution
  • Stars: mass loss

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Kinematic structure of H 2 and [Fe II] in the bipolar planetary nebula M2-9. / Smith, Nathan; Balick, Bruce; Gehrz, Robert D.

In: Astronomical Journal, Vol. 130, No. 2, 08.2005, p. 853-861.

Research output: Contribution to journalArticle

Smith, Nathan ; Balick, Bruce ; Gehrz, Robert D. / Kinematic structure of H 2 and [Fe II] in the bipolar planetary nebula M2-9. In: Astronomical Journal. 2005 ; Vol. 130, No. 2. pp. 853-861.
@article{7cd093ba9f4a4a1fad4ee7a561399321,
title = "Kinematic structure of H 2 and [Fe II] in the bipolar planetary nebula M2-9",
abstract = "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] λ16435 and H 2 v = 1-0 S(1) λ21218. 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] λ6583, 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 visual-wavelength 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 η Car, despite the different central engines powering the two nebulae.",
keywords = "Circumstellar matter, Planetary nebulae: general, Planetary nebulae: individual (M2-9), Stars: evolution, Stars: mass loss",
author = "Nathan Smith and Bruce Balick and Gehrz, {Robert D.}",
year = "2005",
month = "8",
doi = "10.1086/431253",
language = "English (US)",
volume = "130",
pages = "853--861",
journal = "Astronomical Journal",
issn = "0004-6256",
publisher = "IOP Publishing Ltd.",
number = "2",

}

TY - JOUR

T1 - Kinematic structure of H 2 and [Fe II] in the bipolar planetary nebula M2-9

AU - Smith, Nathan

AU - Balick, Bruce

AU - Gehrz, Robert D.

PY - 2005/8

Y1 - 2005/8

N2 - 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] λ16435 and H 2 v = 1-0 S(1) λ21218. 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] λ6583, 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 visual-wavelength 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 η Car, despite the different central engines powering the two nebulae.

AB - 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] λ16435 and H 2 v = 1-0 S(1) λ21218. 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] λ6583, 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 visual-wavelength 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 η Car, despite the different central engines powering the two nebulae.

KW - Circumstellar matter

KW - Planetary nebulae: general

KW - Planetary nebulae: individual (M2-9)

KW - Stars: evolution

KW - Stars: mass loss

UR - http://www.scopus.com/inward/record.url?scp=24944490823&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=24944490823&partnerID=8YFLogxK

U2 - 10.1086/431253

DO - 10.1086/431253

M3 - Article

AN - SCOPUS:24944490823

VL - 130

SP - 853

EP - 861

JO - Astronomical Journal

JF - Astronomical Journal

SN - 0004-6256

IS - 2

ER -