Protoplanetary Nebula (PPN)

A protoplanetary nebula (PPN) represents the evolutionary stage between the end of the asymptotic giant branch (AGB) stage and the planetary nebula (PN) stage of an intermediate-mass star.

Within this short period, the strong infrared shining central star (CS) illuminates the ejected shells. The envelope shape changes from spherically symmetric (concentric rings) to axially symmetric and forms the frequently observed bipolar structures, depending on the line of sight. The remaining dust, usually donut-shaped around the CS, blocks the light and forms the constricted morphology between the bipolar outflows. The star itself is still not hot enough to ionize the surrounding remnants, causing the visible nebula to be a reflection nebula.

Because of the young age and the limited illumination power of the CS, the objects are small and they hence appear usually much smaller than the familiar PNs. Good seeing and high magnifications are required for successful observations. Due to the absent ionization, nebula filters don't have any effect. In rare cases the light of a PPN is significantly polarized such that this effect could be observable using a mid size amateur telescope. Common polarization filters may show a fading or brightening of the nebula while being rotated. The "Egg Nebula" is the best example of this effect.

CRL 618 "Westbrook Nebula"


HST

DSS b 5'x5'


36" sketch
(click to enlarge)

27", 837x, fst 6m5+, seeing III
brighter E component steadily visible with averted vision; fainter W component not visible

27", 586x, fst 7m0+, seeing II
brighter E component direct visible as a very small but 1:2 E-W elongated plob; fainter component not visible

36", 581x, fst 7m0+, seeing III
direct visible brighter part; brighter E part with center bulge, no folk structure at the E end; fainter W component repeatedly visible and separated for seconds each; faint, but 1:2 E-W elongated; smaller than the brighter E part
 


HD 44179 "Red Rectangle"


HST

DSS r 5'x5'


27" sketch
(click to enlarge)

8", 114x, fst 6m5+
with searching eyepiece a bright, direct visible, slightly orange star is visible; star has a slightly larger halo than other similar bright stars; no form or structure visible

16", 257x-600x, fst 6m5+, seeing IV
bright, orange CS; rectangle structure not visible

27", 733x, fst 6m5+, seeing IV
9mag bright orange CS star HD 44179 (V777) dominate area and create a star radiation halo; with small to mid size magnification a 1' long N-S elongated bar like structure is visible within the halo; with higher magnification the radiation halo disappears and the structure of the rectangle starts to be visible more clearly; the former bar now forms a conical structure starting from the star; the edges of the conical structure are good defined with the best defined edge at the SW side; within the structure the nebula seems to be a little bit mottled without showing clearly structures; no filter reaction


SRWW 1

INT

DSS r 5'x5'


27" sketch
(click to enlarge)

27", 293x-419x, fst 7m0+, seeing III-IV
soft seeing but very good transparency; visibility not a question of seeing but transparency; CS bright and steadily direct; already with 293x a very faint glow E of the CS is visible; concentrated observation brings out a ~0,5' large glow which sits directly E of the CS and seems to be a little bit brighter towards the star; 419x power seems to be the sweet spot; at the W side the brightening is much more difficult to detect; with averted vision a diffuse and very dim glow pops in and out of view between the CS and a faint DS; glow seems to be somewhat shorter and is more separated from the CS


OH 231.8+4.2 "Rotten Egg Nebula"


HST

DSS r 5'x5'
16", 450x, fst 6m5+; seeing II
stellar spot hard to see with averted vision; not steadily visible; no structure

20", 562x, fst 7m5+, seeing II
nebula visible as a stellar spot; steadily visible with averted vision; no UHC filter reaction; no structure

27", 419x, fst 6m5+, seeing III
23" SSW of a 14mag star (GSC 542201963) a very faint knot is popping in and out a view; not steadily visible; otherwise absolutely nothing visible of the knots and elongated object

36", 348x, fst 6m5+, seeing III
the with 27" observed and above mentioned knot is now steadily visible as a slightly diffuse glow; no other details could be seen


IRAS 09371+1212 "Frosty Leo"

HST

DSS b 5'x5'


27" sketch
(click to enlarge)

8", 400x, seeing III
direct visible object even in the searching eyepiece; up to 80x stellar appearance; from 229x slightly diffuse; with 400x 3:2 NW-SE elongated; looks like a sharp ended parallelogram; a extremely small dark structure is popping in and out of view in the central area, size and orientation not determinable

20", 402x-575x, fst 6m5+, seeing III
very small but bright nebula; with high magnification a small separated structure is visible in the middle; S part seems to be a little bit brighter; with averted vision faint extensions to the NW and SE are visible; NW extension a little bit brighter

27", 837x, fst 6m5+, seeing II
small nebula dominated from a bright double structure in the middle; both halves are separated with a dark bend lane; S half is brighter and has a stellar peak at the W end, to its E end a short extension to the SE is visible; contrary from the fainter half a fainter extension is visible from the W end to the NW; beside the bright and small middle part two faint far-reaching extensions to the NW and SE are visible; brighter NW extension is connected to the bright middle part and ends with a knot; SE part is only visible as a detached knot


CW Leonis "Peanut Nebula"


HST


VLT


DSS b 5'x5'


DSS r 5'x5'


27" sketch
(click to enlarge)
27", 293x, fst 6m5+
extremely difficult object at the limit of the perception; a very faint diffuse glow is popping in and out of view with 2,4mm EP; not visible with max. EP and 4mm EP; 60/40 positive observation, position of the popping is right; not steadily visible; glow seems to be slightly concentrated and is around 0,5' large; red central star is not visible

Henize 3-401


HST

DSS r 5'x5'


28" sketch
(click to enlarge)

28", 891x, fst 7m5+, seeing II
direct visible small, thin, 4:1 elongated nebula; separated with a dark lane; around dark lane brighter spots E and W; W spot a little bit brighter; fainter extensions to both sides with similar length; W extension a little bit brighter

Henize 3-404


HST

DSS r 5'x5'
no observation yet

ESO 172-7 "Boomerang Nebula" ("Centaurus Bipolar Nebula")

HST

DSS r 5'x5'


28" sketch
(click to enlarge)

12", 375x, fst 7m5+, seeing III
bright, direct vision nebula; stellar and bright center; 1:4 elongation with extensions to the S and N; both extensions with no fan structure; S extension a little bit brighter

24", 687x, fst 7m5+, seeing III
bright, somewhat mottled center around stellar spot with fan-shaped extensions to the S and N; S extension brighter 

28", 780x, fst 7m5+, seeing II
bright stellar spot in the center; sometimes double effect like a very close double star?; S fan brighter and longer; SE side more angled than SW side; whole N fan with much less conical fan-shape than the S side; no positive filter reaction


IRAS 13208-6020

HST

DSS r 5'x5'


28" sketch
(click to enlarge)

28", 1040x, fst 7m5+, seeing II
direct visible but very small nebula; 3:1-4:1 SE-NW elongation around direct visible CS; dominated from a very bright center with knot or second peak directly SE of the CS; faint, not so long extensions; both extensions seems to be similar bright and long

IRAS 16342-3814 "Water Fountain Nebula"

HST

DSS r 5'x5'
no observation yet

IRAS 16594-4656 "Water Lily Nebula"

HST

DSS r 5'x5'
no observation yet

Minkowski 2-9 "Butterfly Nebula" ("Twin Jet Nebula")

HST

DSS r 5'x5'


16" sketch
(click to enlarge)



27" sketch
(click to enlarge)

16", 360x, fst 7m0+, seeing II
small and faint appearance; CS easy and direct visible; faint and thin extensions to N and S, ~1' long

27", 837x, fst 6m5+, seeing III
already elongated object around bright CS with searching eyepiece (113x); with high magnification both wings not uniformly conical but bulgy with knots behind the widest position of the wings, brighter wing and knot to the N; faint but direct visible second star some arc seconds NW of the CS


Preite-Martinez 2-23

HST

DSS r 5'x5'
no observation yet

IRAS 17150-3224 "Cotton Candy Nebula"


HST

DSS r 5'x5'


28" sketch
(click to enlarge)

24", 687x, fst 7m5+, seeing III
bright central part already visible in the searching magnification; with higher power the central area seems to be slightly diffuse without showing the faint extensions

28", 1248x, fst 7m5+, seeing I-II
direct vision object; with high power two separated, 1:2 elongated parts; divided with a small dark lane; both extensions similar long and bright; a brighter knot sits directly NW over the dark lane in the NW part


Henize 3-1379 "Fried Egg Nebula"


VLT

DSS r 5'x5'
no observation yet

Preite-Martinez 2-27 "Walnut Nebula"

HST

DSS r 5'x5'
no observation yet

Henize 3-1475 "Garden Sprinkler Nebula"

HST

DSS r 5'x5'


27" sketch
(click to enlarge)

27", 1172x, fst 7m0+, seeing II
bright, direct vision main body; main body itself 3:2 elongated with stellar peak at its SE edge; NE extension visible from 837x up; best view 1137x; extension thin but steadily visible with averted vision; starting from the main body first brighter part, than small but fainter part till a stellar peak at its NW end; no thin extension to the SE, but only a slightly brightening; no reaction with UHC

IRAS 17441-2411 "Silkworm Nebula"


HST

DSS r 5'x5'


28" sketch
(click to enlarge)

28", 1040x, fst 7m5+, seeing II
extremely small nebula; under good seeing conditions the somewhat elongated nebula dissolves into two peaks; roughly N-S elongated; difficult to split

IRAS 18059-3211 "Gomez's Hamburger"


HST

DSS r 5'x5'


28" sketch
(click to enlarge)

27", 293x-419x, fst 7m0+, seeing IV (latitude 47,1N)
under bad seeing but good transparency direct vision object and not difficult to see; diffuse appearance; no separation, no elongation

27", 837x, fst 7m0+, seeing III (latitude 47,1N)
under average seeing for the small horizon distance 2:3 N-S elongated patch of light; separation or dark lane not visible

28", 1560x, fst 7m5+, seeing I-II (latitude 23,2S)
direct vision 1:2 N-S elongated, diffuse smudge; dark lane visible as a very thin, hard defined line; line not continuously visible; brighter W part; W part seems to be slightly bend; bending difficult to define but nebula definitely not straight


MWC 922 "Red Square Nebula"


Keck II / Hale

DSS r 5'x5'
no observation yet

CRL 5497 (V445 Sct)


HST

DSS r 5'x5'
no observation yet

Preite-Martinez 2-39 "Starfish Nebula"


HST

DSS b 5'x5'
27", 837x - 1137x, fst 7m0+, seeing II
with 419x stellar peak which is steadily visible with averted vision; from 837x up the stellar peak seems to be a little bit diffuse against similar bright stars; no elongation, no central peak or other details visible

Minkowski 1-92 "Footprint Nebula"


HST

DSS b 5'x5'


16" sketch
(click to enlarge)



27" sketch
(click to enlarge)

16", 600x, fst 7m0+, seeing II
separation clear but not so easy; brighter part to the NW, slightly elongated; fainter component SE smaller

18", 579x, fst 7m0+, seeing III
bright object; easy to separate; brighter and larger part to the NW

27", 1465x, fst 7m0+, seeing I-II
brighter knot to the NW with good and hard defined edge to the middle, drop shaped extension to the NW, at the end dark space between drop edges; SE part fainter and much smaller, triangle form with slightly bend edge to the middle, brightening in the middle very difficult to see; CS as a stellar peak directly attached to the bright rim of the NW part, hard to separate and not steadily visible; second star S of the CS direct visible, star to the E is popping in and out of view


IRAS 20068+4051


HST

DSS b 5'x5'
27", 837x, fst 7m0+, seeing II-III
object is popping in and out of view; sure detection but not steadily visible; no elongation detected

CRL 2688 "Egg Nebula"

HST

DSS b 5'x5'


16" sketch
(click to enlarge)

16", 600x, fst 6m0+, seeing III
two bright, easy to separate knots; brighter N knot laminar and drop shaped, faint extensions to the N with better defined W edge; S knot nearly stellar, somewhat N-S elongated, very faint extensions to the S, much shorter than the N counterpart

18", 810x, fst 7m0+, seeing II
bright main knots; extensions out of the N part brighter and wider; S extension narrower; no conical or folk shape visible

27", 977x, fst 7m0+, seeing II
both main and bright knot itself slightly conical; extensions easy to see and direct visible; both extensions clearly conical, both shows folk shape with better defined edges like a "peace sign"


IRAS 22036+5306


HST

DSS b 5'x5'
27", 837x-1172x, fst 7m0+, seeing II-III
steadily visible with averted vision; 1:2 elongation NE-SW; center a little bit brighter

36", 819x, fst 7m0+, seeing III
direct visible but very small object; 1:2 NE-SW elongated


CRL 3068


HST

DSS b 5'x5'
27", 419x, fst 7m0+, seeing III
once popping with 419x (EP 1,6mm) with averted vision; laminar character with 0,5' size; extremely difficult

36", 505x, fst 7m0+; seeing IV
extremely faint glow is popping in and out of view; not steadily visible; 0,5' large, diffuse; co-observer does see similar glow with similar difficulties

 

Data:

Designation Nickname Star PNG / PK IRAS RA DEC Brightness Size
CRL 618 Westbrook V353 Aur 166.4-06.5 / 04 42 54 +36 06 53 16,3bmag 14"x3"
HD 44179 Red Rectangle V777 Mon / 06176-1036 06 19 58 -10 38 15 9,0vmag 52"x38"
SRWW 1 / GSC2 S1002033937 / 07131-0147 07 15 42 -01 52 42 15,4bmag ~67"x19"
OH 231.8+4.2 Rotten Egg
Calabash
QX Pup / 07399-1435 07 42 17 -14 42 50 17,3bmag
16,3vmag
~55"x28"
~30"x5" (central body)
IRAS 09371+1212 Frosty Leo GSC 00824-01094 / 09371+1212 09 39 54 +11 58 53 11,0vmag ~28"x12"
IRC +10216 Peanut CW Leo 221+45.1 09452+1330 09 47 57 +13 16 44 11,0rmag ~13' (emission arc)
Henize 3-401 / GSC 08956-02606 285.1-02.7 10178-5958 10 19 33 -60 13 29 12,5vmag 10"x2,5"
Henize 3-404 / GSC 08608-00509 / 10197-5750 10 21 34 -58 05 48 12,3vmag ~11"x7"
ESO 172-7 Boomerang
Centaurus Bipolar
/ / 12419-5414 12 44 46 -54 31 13 12,7vmag 55"x21"
IRAS 13208-6020 / / / 13208-6020 13 24 04 -60 36 31 15,8bmag ~14"x2"
IRAS 16342-3814 Water Fountain GSC2 S230321328946 / 16342-3814 16 37 40 -38 20 17 15,7vmag 4"x2,5"
IRAS 16594-4656 Water Lily GSC2 S230023014967 340.3-03.2 16594-4656 17 03 10 -47 00 28 14,6vmag 4,6"x2,2" (central body)
Minkowski 2-9 Butterfly
Twin Jet
GSC2 S223220328 010.8+18.0 17028-1004 17 05 38 -10 08 35 14,7vmag 48"x12"
115"x18" (outflows)
Preite-Martinez 2-23 / GSC2 S222332178351 / 17106-3046 17 13 52 -30 49 41 16,0vmag 2,54"x1,75"
7,73"x6,59" (halo)
IRAS 17150-3224 Cotton Candy GSC2 S222330241876 / 17150-3224 17 18 20 -32 27 22 14,3vmag 6,6"x2,4" (main lobes)
9,4" (arcs)
13,8"x15,8" (halo)
Henize 3-1379 Fried Egg GSC 07870-01348 / 17163-3907 17 19 49 -39 10 38 12,5vmag 2,25" (inner shell)
50" (outer shell)
Preite-Martinez 2-27 Walnut GSC2 S222031027823 / 17245-3951 17 28 05 -39 53 44 15,5vmag 2,23"x0,6" (lobes)
2,8"x2,1" (halo)
Henize 3-1475 Garden Sprinkler GSC 06253-02182 009.3+05.7 17423-1755 17 45 14 -17 56 47 12,2vmag 15,4"x2"
IRAS 17441-2411 Silkworm GSC2 S22210327737 / 17441-2411 17 47 13 -24 12 51 15,1vmag 3,8"x1,6" (lobes)
6,4"x5,2" (halo)
IRAS 18059-3211 Gomez's Hamburger / / 18059-3211 18 09 13 -32 10 48 14,4vmag 5,5"x2,5"
MWC 922 Red Square /   18184-1302 18 21 16 -13 01 26 14,0vmag ~4"x4" (inner square)
~11"x13" (outer square)
OH 17.7-2.0 / / / 18276-1431 18 30 31 -14 28 57 (14,4vmag) ~1"x0,5" (knots)
4,5"x3,4" (halo)
Preite-Martinez 2-39 Starfish GSC2 N020131010573 / 19024+0044 19 05 02 +00 48 51 16,6vmag 3,7"x2,3"
Minkowski 1-92 Footprint VES 20 / 19343+2926 19 36 19 +29 32 51 11,8vmag 11,5"x4,5"
IRAS 20068+4051 / / / 20068+4051 20 08 38 +41 00 41 17,8vmag ~13"x3"
CRL 2688 Egg V1610 Cyg 080-06.1 / 21 02 18 +36 41 37 11,5vmag ~80"x20" (beams)
~41" (arcs)
IRAS 22036+5306 / GSC2 N0321212106560 / 22036+5306 22 05 30 +53 21 33 16,4vmag 5,7"x1,3"
CRL 3068 / LL Peg / 23166+1655 23 19 13 +17 11 33 ~19bmag? ~40" (faint arc halo)

DSS Bilder: Space Telescope Science Institute (California Institute of Technology, National Science Foundation, the National Geographic Society, the Sloan Foundation, the Samuel Oschin Foundation, Eastman Kodak Corporation)