The goal of this catalog is to provide easy access to high-spatial-resolution optical images of objects that have ejected gas and dust, and are expected to evolve to become planetary nebulae. Hubble Space Telescope images of pre- and very young PNe were downloaded from the MAST/Hubble Archives(1) and the Hubble Legacy Archive(2), processed and aligned using standard software, and, in most cases, overlaid in various colors to form the eighty images shown below. The images are tagged by their IRAS designations except for the Egg Nebula for which no IRAS number is reported in the SIMBAD(1) catalog (simbad.u-strasbg.fr/simbad/). Please see the legend of each image for documentary information and credits. I caution that there may be additional images in the Hubble Archives since April 2008, or possibly images that could not be identified by the keywords used by the proposers. Images that fail to show resolved structure are not included or compiled in this catalog.
The Catalog of Hubble Images of Nascent and Infantile Planetary NebulaeBruce Balick, Joe Huehnerhoff, and Jennifer Baerny
Astronomy Department, Universityof Washington
This web page is still a work in progress.
Please be sure to use the appropriate citationin progress,
and please be sure to credit the original source of each image.
The images are identified by their galactic coordinates, continuing a nomenclate that has been adopted for PNe by Acker and extended to post-AGB objects in theThe Torun Catalogue of Galactic Post-AGB and Related Objects" (R. Szczerba, N. Siodmiak, P. Garcia-Lario, O. Suarez, G. Stasinska, J. Borkowski 2008, to be published (hereafter theTorun Catalogue); www.ncac.torun.pl/postagb2). The nebula classifications are also shown (see below for details). Below each of the images is a legend. The top line of the legend gives IRAS, 2MASS, and common names when available. These were taken from the SIMBAD catalogue. We shall use IRAS names for future reference with the expection of the Egg Nebula, CRL 2688, which is not in the IRAS catalog.
RA and dec coordinates are in decimal degrees when they were available from the Torun Catalogue; o; otherwise the coordinates are in hours and degrees taken from SIMBAD. The field of view (FOV) of the image is shown along with information about the filters used for the observations. When only two filter imags are available then the filter with the longest wavelength is in the red image plane, that of the shortest wavelength is shown in blue, and the average of the two, orcombis shown in green. In these cases the images take on a deep orange and blue-green appearance. Credits are shown on the bottom line. The original images can be downloaded for analysis from the Hubble Legacy Archive or the Hubble Archives.
The HST images of pPNe were not obtained in any particularly uniform manner: cameras, filters, exposure times, and undoubtedly in some cases, inaccurate coordinates play roles that cannot be ascertained. Worse still, the target selection method varies enormously from one proposal to another. Some proposals select by optical color, others by infrared colors, some by OH masers, and some are selected for nothing more than their long record of study (e.g., the Red Rectangle). In short, the selection biases for this sample are many, and we cannot predict whether this group of pre- or young-PNe are typical in any way. We can only hope that there is safety in numbers.
We wish to acknowledge the work of many people whose work made these images possible. Of particular note are Raghvendra Sahai, Margeter Meixner, Sun Kwok, Bruce Hrivnak, their many collaborators, other people who are not named here but whose images we have used, and of course the people who support the HST Archives(2) and the Hubble Legacy Archive(3).
The images are shown in three groups and two subgroups. The groups are: AGB nebulae, post-AGB-nebulae, and young planetary nebulae. The boundaries that separate these classes are not well defined. Nebulae have been classifiedpost-AGBif they appear in the 2008 edition of the Torun Catalogue (www.ncac.torun.pl/postagb2) or if they are listed as post-AGB pbjects in SIMBAD. Other classifications come from SIMBAD or, in a small number of cases, suggestions made by the authors of papers in which the images appeared. Different authors define classes of objects in a wide variety of ways, so some of the classifications used here may not be uniform.
Each group is divided into two subgroups: those with evidence of a lane or disk of circumnuclear dust in optical images, and those without. Within each subgroup, pPNe with similar morphologies are grouped together in the images below. This determination is made by eye. Those objects for which a planar layer of dust lies near the plane of the sky, or for which the dust absorption and scattering opacities are small will obviously be misclassified. Roughly half of the sample is found in each subgroup. Further subcategorization by morphology is possible but limited by a variety of insidious problems, not the least of which are signal-to-noise ratio, complex wings on point spread functions, severe local extinction, and inadequate spatial resolution.
The search for resolved structure is often hampered by the appearance of a bright star and its diffraction pattern. The point-spread function of the cameras on HST differ from one another. No attempt was made to measure and subtract the PSF to uncover structures. Instead, once the images were calibrated we carefully examined the logarithmic displays of the images and used our judgement to decide whether the image was sufficiently resilved to be included in this catalog. The most dubious cases are those of IRAS09425-6040, an extremely red carbon star (bright at 600nm but absent at 435nm) and IRAS17279-1119.
SUMMARY OF RESULTS
We find that the frequency of core dust lanes is lowest (about 1/3) in pre-AGB Objects compared to other classes (about 1/2), but the small sample size (15 objects of pre-AGB objects) renders that conclusion uncertain. Symmetry about one axis is common (58 of the entire sample of 80 objects). Symmetry about multiple axes is found in about 20% of the entire sample and varies with classification (i.e., evolutionary state): none of 15 pre-AGBs objects, 7 of 54 post-AGBs, and 4 of 11 young PNe have multiaxial symmetries. The increasing fraction of multiple symmetry axes is probably real; however, the numbers are small. Round pPNe are rare; however, such objects may be difficult to recover without a subtraction of the Airy rings of the PSF in many cases. Note that the single-axis symmetry is all but imposed by a dust lane unless, of course, multiple symmetry axes are readily distinguishable.
The appearance of an optical image is the result of dust-scattered starlight unless the gas is ionized. In both cases the distribution of light is determined only in part by the spatial distribution of gas or dust particles. Particularly in reflection nebulae the geometry we see is that of the subset of dust particles that are illuminated by starlight. The illumination pattern is shaped by dust near the nucleus, and the flux of scattered light will generally decrease as r^-2. Dense knots can impose artificially strong finger-like ionization structures even when the gas is otherwise fairly uniform in distribution. This effect is well known in mature PNe, and may help to explain the shapes of someStarfishnebulae (Sahai & Trauger 1998 and subsequent papers), especially when the onset of ionizing radiation is recent.
Three additional image compilations appear at the end of the HST image catalogue. The first of these consists of ten objects that show evidence of rings or ring-segments (calledarcs) outside of the core. These arcs are generally believed to be formed during the ascent of the AGB (that is prior to the onset of the ejection of the denser cores). Like the cores, the arcs are illuminated by starlight and detected only if they lie outside the shadows of inner structures. In the second compilation we show three objects with possible one-armed spiral structures, at least so it appears after geometric projection. If the spiral structures are intrinsic then they may well be the result of overflow from a mass-exchange close binary star system (e.g Mastrodeomos & Morris 1998 and subsequent papers). Hoewver, a quick claculatioin shows that the orbital period of these stars would have to be well over a century, calling into question the proximity of the members of the binary system from which the overflow is ejected unless the outflow speeds are well over 100 km/s.
The third compilation (at the very end of this page) is a comparison sample of low-ionization PNe, all taken from GO6353 (PI: Sahai). The purpose for this addendum is to provide a set of young PNe that are just emerging from the pPN evolution phase. Unfortunately there is no clear way to defineyoung, so as a proxy we use low ionization (Halpha >> [OIII]), which was the primary selection criterion for GO 6353. (We omit many other low-ionization PNe scattered through the HST archives, some of which are huge bipolars such as Hubble 5, NGC 2440, and NGC 6537; however, this set of young PNe forms as good a uniform sample as any we can imagine.
One striking result is that none of the low-ionization (i.e. young) PNe exhibit evidence of dust lanes, which is a precipitous change from all other other classes of PNe presented here (IRAS 04333+3333 = PN K 3-66 may be an exception since it has obvious equatorial ionization shadows that imply that a dark disk is present. Another result is the relatively large fraction of young PNe that show elliptical morphologies. Perhaps this is simply the result of the sudden "pulse" of thermal pressure at the onset of ionization as the ionization front sweeps into the once-neutral gas and the shock that precedes it disrupts the complexity of the nebular geometry. We also notice that none of this sample has arcs, rings, or pinwheels, all of which are comparably rare in mature PNe.
Click on the image thumbnail or its name for the large image and legend. Use your browsers "Find" tool to locate objects - IRAS names are used wherever possible. If you don't know the IRAS name then use SIMBAD to find it.
North is at the top of each image. Objects with similar morphologies are presented near one another in the table ofimages (from left to right).
Compilation I: HST Images of Extended Structures in the Cores (80 objects)
AGB Nebulae (note 4)(15 objects)With Dust Lanes (morphology subclassificaions: 4 bipolars, 1 complex)
[OH 329.14 +3.92]
Without Dust Lanes (morphology subclassificaions: 1 elliptical, 2 bipolars, 1 complex, 6 unclassifiable)
[GLMP 823, OH 27.5-0.9]
[OH 44.8-2.3, CRL2374]
[OH 128.6-50.1, IRC+10011]
Post AGB Nebulae (54 objects)With Dust Lanes (morphology subclassificaions: 24 bipolars, 4 multipolars)
[HD 44179, RED RECTANGLE]
[OH 348.81-2.84, GLMP565]
[Hen 3-404, Roberts22,
[GLMP632, Hen 3-1475]
[OH231.8+04.2, Rotten Egg, GLMP191]
[Hen 3-401, GLMP270]
[OH 353.84+2.98, GLMP540]
[GLMP640, CRL 5385]
[OH 17.7-2.0, CRL 5497]
[GLMP591, OHPN5, PN RPZM28]
[GLMP480, OH 344.1+5.8]
Without Dust Lanes (morphology subclassificaions: 7 elliptical, 14 bipolars, 4 complex, 1 unclassifiable)<
[GLMP1059, HD 235858]
[GLMP 639, CRL 5384]
[GLMP1078, PN PM 2-47]
[PN PM 1-176]
[PN M 2-56]
[GLMP951, PN PM 2-42]
[HD179821, CRL 2343]
Young Planetary Nebulae (11 objects)With Dust Lanes (morphology subclassificaions: 6 bipolars, 1 multipolar)
[Hen 2-90, PK305+01 1]
[OH 56.1+2.1, K 3-35,
[PN PM 1-150]
[GLMP1068, PN PM 1-339]
[GLMP620, OH 0.9 +1.3, PN PM 1-173]
[PN K 3-52, PK 067-00 1]
Without Dust Lanes (morphology subclassificaions: 3 multipolars, 1 complex)
[PN PM 1-153]
[Hen 2-166, PN Pe 1-7]
[Hen 3-1333, PK 332-09 1]
Compilation II: HST Images of Showing Rings and Arcs (10 objects)
[OH 353.84+2.98, GLMP540]
[GLMP640, CRL 5385]
[OH 128.6-50.1, IRC+10011]
[Hen 3-404, Roberts22, OH 284.2-0.8]
Compilation III: HST Images of Pinwheels and Spirals (4 objects)
[PN K 3-52, PK 067-00 1]
Compilation IV: Comparison Sample: Young pPNe (19 objects from GO6353/Sahai)
With Dust Lanes (none)
Without Dust Lanes (morphology subclassificaions: 5 ellipticals, 8 bipolars, 3 multipolars, 2 complex, 1 unclassifiable)
[PN Cn 3-1]
[Hen 2-182, PN Sa 2-157]
[Hen 2-131, PN SaSt 2-9]
[Hen 2-138, PN SaSt 2-10]
[PN M 4-18]
[Hen 2-142, PN SaSt 2-11]
[PN K 3-66]
[PN Me 2-2]
[PN Hb 12]
[Hen 2-104, Southern Crab]
[Hen 2-115, PN Sa 2-112]
[Hen 2-339, PN M 1-37]
[Hen 2-47, PN SaSt 2-5]
[Hen 2-71, PN SaSt 2-7]
[Hen 2-277, PN M 1-26]
[PN Vy 2-2, PN M 1-70]
(1) Much of the data presented in this catalog were obtained from the Multimission Archive at the Space Telescope Science Institute (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NAG5-7584 and by other grants and contracts.
(2) Many of the images presented in this catalog were obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA) and the Canadian Astronomy Data Centre (CADC/NRC/CSA).
(3) This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France
(4)AGB Nebulaeare extended regions associated with objects that are not listed as Post-AGB Objects in the Torunn Catalogue or SIMBAD and that surround stars with late-type spectra.