Extended Structures of Planetary Nebulae Detected in H2 Emission (original) (raw)
Related papers
On the relationship between the H2 emission and the physical structure of planetary nebulae
Monthly Notices of the Royal Astronomical Society, 2013
Mid-IR observations of planetary nebulae (PNe) have revealed diffuse emission associated to their main nebular shells and outer envelopes or haloes. The interpretation of this emission is uncertain because the broad-band mid-IR images may include contributions of different components. In particular, the Spitzer IRAC 8 µm images, that best reveal these nebular features, can include contributions not only of H 2 lines, but also those of ionic species, PAH features, and thermal dust continuum emission. To investigate the nature of the emission detected in mid-IR observations of a sample of 10 PNe, we have obtained narrow-band near-IR H 2 λ2.122 µm and optical [N ii] λ6584Å images. The comparison between these images confirm that a significant fraction of the emission detected in the IRAC 8 µm images can be attributed to molecular hydrogen, thus confirming the utility of these mid-IR images to investigate the molecular component of PNe. We have also detected H 2 emission from PNe whose physical structure cannot be described as bipolar, but rather as ellipsoidal or barrel-like. These detections suggest that, as more sensitive observations of PNe in the H 2 λ2.122 line are acquired, the detection of H 2 emission is not exclusive of bipolar PNe, although objects with this morphology are still the brightest H 2 emitters. Finally, we remark that the bright H 2 emission from the equatorial ring of a bipolar PN does not arise from a photo-dissociation region shielded from the UV stellar radiation by the ring itself, but from dense knots and clumps embedded within the ionized material of the ring.
Investigating the Near-Infrared Properties of Planetary Nebulae. I. Narrowband Images
The Astrophysical Journal Supplement Series, 1995
We present medium-resolution (R ∼ 700) near-infrared (λ = 1 − 2.5 µm) spectra of a sample of planetary nebulae (PNe). A narrow slit was used which sampled discrete locations within the nebulae; observations were obtained at one or more positions in the 41 objects included in the survey. The PN spectra fall into one of four general categories: H I emission line-dominated PNe, H I and H 2 emission line PNe, H 2 emission line-dominated PNe, and continuum-dominated PNe. These categories correlate with morphological type, with the elliptical PNe falling into the first group, and the bipolar PNe primarily in the H 2 and continuum emission groups. The categories also correlate with C/O ratio, with the O-rich objects generally falling into the first group and the C-rich objects in the other groups. Other spectral features were observed in all categories, such as continuum emission from the central star, C 2 , CN, and CO emission, and warm dust continuum emission towards the long wavelength end of the spectra.
H 2 Imaging of Three Proto–Planetary and Young Planetary Nebulae
The Astrophysical Journal, 2004
High-resolution (0B15) 2.12 m H 2 and narrowband K images have been obtained of one cool proto-planetary nebula, IRAS 20028+3910, and two hot proto-planetary/young planetary nebulae, IRAS 19306+1407 and IRAS 22023+5249. The observations were made with an adaptive optics system and near-infrared imager on the Gemini North 8 m telescope. All three nebulae are seen to be extended, and in two and possibly all three of them H 2 is found to be emitting from bipolar lobes. In IRAS 19306+1407, H 2 emission is seen arising from a ring close to the star and from the edges of emerging bipolar lobes. In IRAS 20028+3910, one bright lobe and a very faint second lobe are seen in the H 2 and K-band images, similar to the published visible images, but in the H 2 and K-band images a faint filament appears to connect the two lobes. The central star is not seen in IRAS 20028+3910, indicating that the nebula is optically thick even at 2 m, which is unusual. The images suggest that extended H 2 emission is often the manifestation of fast-slow wind interactions in the bipolar lobes. Subject headingg s: circumstellar matter -infrared: ISM -infrared: stars -ISM: lines and bandsplanetary nebulae: general -stars: AGB and post-AGB
Investigating the Near‐Infrared Properties of Planetary Nebulae. II. Medium‐Resolution Spectra
The Astrophysical Journal Supplement Series, 1999
We present medium-resolution (R ∼ 700) near-infrared (λ = 1 − 2.5 µm) spectra of a sample of planetary nebulae (PNe). A narrow slit was used which sampled discrete locations within the nebulae; observations were obtained at one or more positions in the 41 objects included in the survey. The PN spectra fall into one of four general categories: H I emission line-dominated PNe, H I and H 2 emission line PNe, H 2 emission line-dominated PNe, and continuum-dominated PNe. These categories correlate with morphological type, with the elliptical PNe falling into the first group, and the bipolar PNe primarily in the H 2 and continuum emission groups. The categories also correlate with C/O ratio, with the O-rich objects generally falling into the first group and the C-rich objects in the other groups. Other spectral features were observed in all categories, such as continuum emission from the central star, C 2 , CN, and CO emission, and warm dust continuum emission towards the long wavelength end of the spectra.
Near-infrared echelle spectroscopy of protoplanetary nebulae: probing the fast wind in H 2
Monthly Notices of the Royal Astronomical Society, 2005
Echelle spectroscopy of H 2 2.122 µm, [FeII] 1.644 µm and Brγ line emission from a very young planetary nebula, IRAS 21282+5050, and from four proto-planetary nebulae, IRAS 19343+2926 (M 1-92), IRAS 17150-3224 (AFGL 6815), IRAS 17423-1755 (Hen 3-1475), and IRAS 17441-2411 is presented. H 2 line emission is detected in discrete shock fronts in the lobes of each nebula, regardless of source spectral type (although non-detections in IRAS 09371+1212 (Frosty Leo) support claims that late spectral types do not produce bright H 2 line emission). In IRAS 17150-3224 we also uncover possible signs of rotation, as would be expected if the H 2 features were excited in a magneto-centrifugal disk wind.
The Astrophysical Journal, 2008
We have carried out a spatial-kinematic study of three proto-planetary nebulae, IRAS 16594−4656, Hen 3-401, and Rob 22. High-resolution H 2 images were obtained with NICMOS on the HST and high-resolution spectra were obtained with the Phoenix spectrograph on Gemini-South. IRAS 16594−4656 shows a "peanut-shaped" bipolar structure with H 2 emission from the walls and from two pairs of more distant, point-symmetric faint blobs. The velocity structure shows the polar axis to be in the plane of the sky, contrary to the impression given by the more complex visual image and the visibility of the central star, with an ellipsoidal velocity structure. Hen 3-401 shows the H 2 emission coming from the walls of the very elongated, open-ended lobes seen in visible light, along with a possible small disk around the star. The bipolar lobes appear to be tilted 10−15 • with respect to the plane of the sky and their kinematics display a Hubble-like
Morphological study of the nested planetary nebula Hubble 12
Astronomy & Astrophysics, 2021
We present a visible-infrared imaging study of young planetary nebula (PN) Hubble 12 (Hb 12; PN G111.8-02.8) obtained with Hubble Space Telescope (HST) archival data and our own Canada-France-Hawaii Telescope (CFHT) measurements. Deep HST and CFHT observations of this nebula reveal three pairs of bipolar structures and an arc-shaped filament near the western waist of Hb 12. The existence of nested bipolar lobes together with the presence of H2 knots suggests that these structures originated from several mass-ejection events during the pre-PN phase. To understand the intrinsic structures of Hb 12, a three-dimensional model enabling the visualisation of this PN at various orientations was constructed. The modelling results show that Hb 12 may resemble other nested hourglass nebulae, such as Hen 2-320 and M 2-9, suggesting that this type of PN may be common and the morphologies of PNs are not so diverse as is shown by their visual appearances. The infrared spectra show that this PN has...
Spectroscopy and imaging of newly discovered planetary nebulae
Astronomy and Astrophysics Supplement Series, 1996
The major purpose of this paper was to prove or disprove the nature of planetary nebula (PN) candidates in the northern hemisphere, taken from an internal list. We present spectroscopic observations and imaging of fifteen PNe, twelve of them identified for the first time. Another two candidates turned out to be an emission-line galaxy and an H ii region. All observed PNe represent evolved stages, their angular diameter ranging from 8 to 90 , and exhibit very low surface brightnesses. The three largest and faintest nebulae each host a central star of magnitude 18 to 20 m .
Astron J, 2011
Using Hubble Space Telescope images of 119 young planetary nebulae, most of which have not previously been published, we have devised a comprehensive morphological classification system for these objects. This system generalizes a recently devised system for pre-planetary nebulae, which are the immediate progenitors of planetary nebulae (PNs). Unlike previous classification studies, we have focussed primarily on young PNs rather than all PNs, because the former best show the influences or symmetries imposed on them by the dominant physical processes operating at the first and primary stage of the shaping process. Older PNs develop instabilities, interact with the ambient interstellar medium, and are subject to the passage of photoionization fronts, all of which obscure the underlying symmetries and geometries imposed early on. Our classification system is designed to suffer minimal prejudice regarding the underlying physical causes of the different shapes and structures seen in our PN sample, however, in many cases, physical causes are readily suggested by the geometry, along with the kinematics that have been measured in some systems. Secondary characteristics in our system such as ansae indicate the impact of a jet upon a slower-moving, prior wind; a waist is the signature of a strong equatorial concentration of matter, whether it be outflowing or in a bound Keplerian disk, and point symmetry indicates a secular trend, presumably precession, in the orientation of the central driver of a rapid, collimated outflow.
Kinematic Structure of H2and [Feii] in the Bipolar Planetary Nebula M2-9
The Astronomical Journal, 2005
We present new high-dispersion long-slit infrared (IR) spectra of the double-shell bipolar planetary nebula M 2-9 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 M 2-9. 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 M 2-9. 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 M 2-9 and the Homunculus of η Car, despite the different central engines powering the two nebulae.