NEAT SOUTHERN PLANETARIES : 27 He2-60 / Hf 48 in Carina
The following part not appear in the ASNSWI’s Journal “Universe” [March 2012], as it was not completed in
time for Lesa’s deadline (Completely my
own fault.) So instead of observers missing out with a new NSP Series
submission, I have placed NSP 27 here in my own Webpages —
Southern Astronomical Delights. [It was originally linked in
March’ Universe on pg.12.].
Although it is correct as possible, there maybe one or two minor
errors, as it has not been formally edited.
NSP 27 will be further referenced sometime in new future parts of
this series.
In the meantime, I do hope you enjoy this new object,
He2-60.
Probably impossible to see, but a fascinating deep-sky
bipolar planetary of our Southern Skies!
Andrew James 24th March 2012
This section centres on the faint but unusual bipolar
planetary, He2-60, which was discovered from Red Schmidt telescope
plates produced in South Africa. Our ancillary story here also with
the Annals of Harvard College Observatory, being a wonderful
paper published by Hoffleit, D., “A
Preliminary Survey of Nebulosities and Associated B-stars in
Carina” in 1953. [See Ref. 4.]
This is a good read for any visual observers or astroimagers who are
interested in the deep survey of the area around the magnificent Eta
Carinae.
He2-60 / Hf 48 / Sa2-71 / Wray 16-85 / ESO 128-29 /
PK 290-0.1 / PN G290.1-0.4 (11039-6036) is an extraordinary looking
Carina planetary nebula that we presently know very little about. It
is a very tough object for amateur telescopes, with only its tight
luminous central region being the only portion that is like visible
to us. Available catalogued data says He2-60 is 15.0p magnitude and
visually subtends about 19 arcsec across. In the V-V PNe
classification it is oddly as III or 3 — irregular disk —
even though it is clearly now not the case.
Discovered by Dorrie Hoffleit in August 1953 as Hf 48, it was then
next observed and to be later catalogued by Henize (1967) as He2-60.
Here I have preferred using the
‘He2-’
designation, as Hoffleit did find objects that are mixtures of only
just sixty-nine nebulae rather than specific or dedicated PNe
discoveries — although Hoffleit did call Hf 48 as a planetary!
This, with other interesting nebulae, appears all in Hoffleit (1953),
whose quite remarkable paper* investigates the much wider nebulous
region in and around the famed environs of the grand NGC 3372
/ Eta Carinae Nebula / η Car Nebula /
Gum 33 / RCW 55 (10440-5930). This faint PN was discovered on the
sixty minute 103a-E red plate image using the variable aperture
81/90cm. f/2.6 South African Schmidt telescope that was originally
installed at its site near Bloemfontein during 1948. [See the short
but quiet informative book by Marx (1992)].
Fig. 1. He2-60 Wide Field. CDS Aladin
Colour Image about AAO Red (red), IR plates (blue), average (green)
11½′×11½′ in size.
Technical Information
Observationally, this remains a difficult object, but should
respond to the O-III filter. This can be adjudged from
the CGPN data [Ref.1 Acker, A., et al. (1992)], from the relative
line intensity of the blue-green [O-III] (500.7nm.) of
1353, being usually compared to the similar bluish line of the
“standard” Hβ line
(486.1nm) set at 100.0. This is roughly average compared to
the red Hα line (656.3nm.) of
1017, while [NII] (658.4nm.) easily exceeds the
average PNe values of 6083. Redder [SII] lines
(671.7nm. + 673.1nm.) are 207 and 206. This makes the
more likely ratio for [OIII]/Hα at about 3:1., so we can conclude that
any OIII filter may respond quite well. Any
takers? Comparing the energy output by the Hβ flux of NGC 3132 to He2-60, [log -10.45
mW.m-2 against log -12.7 mW.m-2], He2-60 is 180
times less luminous than NGC 3132. Looking at the available
Aladin images, clearly shows the commonly stated bipolar structure,
with its bright waist with many outflows roughly diagonally across
the image. Hoffleit (1953) first describes “Very small “dumb[b]ell.”
Superimosed star not classified.”
Fig. 2. He2-60 Narrow Field. CDS
Aladin Colour Images showing the nebulae in various wavelengths.
Image scale is roughly 30″×30″ for each frame. The
Short Red image shows evidence of the very faint
PNN.
Pascoli (1990) [Paper I] describes Hf 48 as follows;
“The
Hα map (Fig 6.) shows a minor-axis
“I”
shape. The dashed lines outline the ansae which delineate the edges
of the bipolar lobes. These ansae clearly start from both the
extremities of the central bar (a ring seen edge-on) as observed in
[Carina’s brightest planetary,] NGC
2899.”
In Pascoli (1990) [Paper II], he gives the
tentative classification for Hf 48 as
“late butterfly”,
Greig-Sabbandin bipolar classification of
‘B’ [From
Sabbadin (1984, 1986)] whose angle between the major geometric axis
and the line of sight is 80°. He does not give any true radius
nor any equatorial expansion velocity, though Pascoli classes it as
Type 5 in his published paper’s
classification. I have reproduced it here to show the structural
nature of this obvious bipolar planetary. This figure shows the
various lines that have equal brightness or intensity, all just
expressed not in units by as relative numbers. (See Fig. 3.)
← Fig. 3. He2-60 General Structure.
(left) Structure according to gradient light intensity by Pascoli
(1990), who classes it as his Type 5 (pg.189). The shape is slightly
different from below, as the tilt of the line-of-sight is
80°.
Deeper images, like the study made by Hua et al. (1998) using
various telescopes including the 2.3-metre ATT at Siding Spring, show
the size extends to 25×20 arcsec in
Hα, 28×80 in [NII] and
20×65 in [OIII]. These images appear in their
Fig. 6 in this paper, and they look slight different from my Fig.2
presented here. Advanced readers might like to compare images of Hf
48 with other known PNe that they have investigated. Hua, et al.
(1998) says;
“This planetary
nebula is characterised by a quite strong reddening, since the Balmer
decrement is rather high, and by a strong [NII]
emission. The major part consists of a rectangular
(10″×15″) core. The fuzzy (20″×25″)
envelope is very faint.”
Central star or PNN is not listed at all in the literature, but it
seems to be in the Short Red image (Fig. 2.), in the centre of three
different nebulous parts of He2-60’s
very narrow waist. Looking at Pascoli (1990) expectant shape or
morphology (Fig. 3), shows the two bright or intense regions either
side of the waist. Causing this region of intensity is a significant
amount of luminous gas that the observer has to peer through. At the
extreme edges we are looking through a thick region of gas. In the
centre of the waist, the gas is at its thinnest, being more
transparent to light, and so the bright central star can shine
through it. This easily explains what we see.
In Fig. 3, if the observer was looking directly down from above
(0° instead of the observed 80°), we would instead see a
perfectly circular ring that would mimic PNe like the famous famous
and huge apparent sized NGC 7293 / Helix Nebula (22297-2050)
in Aquarius or Centaurus’ Lo 5 /
Longmore 5 (11138-4806).
I could find only one estimate of distance for this planetary,
being 2.0 kpc. by made Maciel (1984). Hua et al. (1998) estimates the
nebula mass as at or below 0.1M⊙ and has the moderate electron
nebula density (Ne) of about 1000
e-.cm-3 (electrons per cubic centimetre)
— the energy fluorescing the nebulosity we see.
Other Morphologies for Hf 48
Hf 48 might not be spectacular in telescopes, but astrophysically,
this is an interesting PNe, and is certainly another southern object
worthy of much closer scrutiny. The closest paper published to date
is by Soker & Rappaport (2000), which discusses the nature of some
forty-three PNe with waists. Hf 48 in this paper is the only
one with a totally blank listing of current knowledge! Advanced
readers might like to read this paper for themselves, as they give a
good summary of these kinds of planetaries, their morphology, and
their complicated wind dynamics. These authors profess that the
structure is formed by binary stars that have a red supergiant star
on the top of asymptotic giant branch (AGB) with a white dwarf
companion, whose orbital semi-major axis is between several AU and
200AU. They explain that the
fast wind is made by collimating an accretion disk to form the
observed bipolar structure. An interesting idea, in light that that
the true cause of the phenomena still has not been explained even
twelve years later.
Hopefully, and soon, perhaps a new dedicated investigation will
come along and likely reveal more details about this unusual bipolar
planetary.
Visual Observations
Visual observers with large apertures might like to attempt this
objects, and possibly be the first to spot it. I could find no
observation to present here, and even eagle-eyed Kent Wallace, has
yet to record Hf 48 / He2-60.
References
- Acker, A., et al., “Strasbourg-ESO Catalogue of Galactic
Planetary Nebulae.”, ESOPN, (1992)
(ISBN 3-923524-41-2) [Useful on-line version at;
Strasbourg- ESO Catalogue of Galactic Planetary Nebulae.]
- Corradi, R.L.M., Schwarz, H.E., “Morphological populations of planetary
nebulae: which progenitors? I. Comparative properties of bipolar
nebulae.”, A&A.,
293, 871 (1995)
- Henize, K.G., “Observations of
southern planetary nebulae.”,
AJ.Sup.Ser., 14, 125 (1967)
- Hoffleit, D., “A Preliminary
Survey of Nebulosities and Associated B-stars in Carina”, A.HCO., 119, 37 (1953)
[Annals of Harvard College Observatory] ADS :
Hoffleit (1953)
- Hua, C.T., Dopita, M.A., Martinis, J., “Detection
of new emission structures around planetary nebulae.”, A&A.Sup.Ser., 133, 361
(1998) [At ADS.]
- Marx, S., “Astrophotography with the Schmidt
Telescope.”, pg.32, Pub. Cambridge
University Press (1992)
- Pascoli, G., “Morphology of
Bipolar Planetary Nebulae. I. The Two-dimensional
Spectrophotometry.”
A&A.Sup.Ser., 83, 27 (1990) [As Paper I.]
- Pascoli, G., “Morphology of
Bipolar Planetary Nebulae. II. The Three-dimensional
Structures.” A&A.,
232, 184 (1990) [As Paper II.]
- Soker, N, Rappaport, S., “The
Formation of Very Narrow Waist Bipolar Planetary Nebulae.”, AJ., 538, 241 (2000) [ADS:
Soker
& Rappaport (2000)
- Westerlund, B.E., Henize, K.G., “Dimensions of Southern Planetary
Nebulae”, AJ.Sup.Ser.,
14, 154 (1967)
Surrounding Objects of He2-60
There are so many objects around here that you could
fill several issues of our Journaled “Universe”. Observers here might like to examine for
themselves the open clusters of Cr 236, Bochum 12, NGC 3496 and NGC
3519 being all nearby and within 1½° of Hf 48 /
He2-60.
1. Cr 236 / Bran 333 / C 1055-607 (10597-6058) is a 7.7b
magnitude cluster that is 7′ across. It only contains about 20
stars, being place some 39′SW (PA 234°) from He2-60.
Remarkably missed in the NGC, this weak scattering of stars have the
poorly Trumpler classification of 3 2 p −. Distance is
800 pc, or about 2¼ times closer than the bright Eta Carinae
nebula.
2. Bo 12 / Bochum 12 (10573-6144) is an open cluster that is
fainter than Cr 238 at 9.7 magnitude that covers about 10′
across. It is populated by 20 stars, whose visual appearance is three
groupings of three 11th magnitude stars among several other fainter
stars. It is best seen in 15cm or 20cm. Location is 48′SSW (PA
200°) of Cr 238 or 1.4°SW (PA 215°) from He2-60. G.
Lyngå classes Bo 12 as Trumpler class II 3 p −.
3. NGC 3496 / Cr 237 / h.3310 / C1057-600 (10597-6020) is
an open cluster about 36′WNW (PA 295°) from He2-60.
Containing about 60 stars, this 8.2v / 9.0b total magnitude cluster
subtends about 9′. Most stars are of 12th magnitude, and all
the stars are brighter by about two magnitudes than the foreground
stars. The whole cluster is visible in 15cm. in good conditions, but
20cm would be better.
Discovered by John Herschel in 1834 during telescope sweep No.
435, who describes;
“Place of a small
double star in the following part of a loose, rich, pretty large
cluster of stars 13 m[ag], 8′ or 10′ diameter; a fine
object; a very much condensed milky way
group.”
Spectral observations do suggest the whole cluster is moving
towards at −51.4 km.s-1. Piskunov et al. (2008)
finds the total mass for NGC 3496 is 198.6±1.9M⊙, whose
linear radius is 7.9±1.7 pc. Age is about 417 Myr. and
distance is a fairly close at 990pc.
4. NGC 3519 / h.3314 / Ru 93 (11041-6122) is the 7.7v
magnitude small 4′ across cluster that lies 46′S (PA
179°) or 20′SSW (PA 200°) from the equal 7.7v
magnitude double star Δ105
(11049-6103).
This open cluster was discovered by John Herschel in 1834 before
his other discovery of NGC 3496. He reported seeing on declination
sweep No.432;
“Chief star of a pretty rich
cluster. Class VII.”
NGC 3519 contains about thirty stars, the cluster appears as a
circular pattern of stars, with three stars forming a slightly
elongated triangle. The very faint circular pattern did not appear
obvious at first, but in 25cm could just make out several wavy lines
of stars to the northeast, northwest and north. Brightest star is the
alleged double, HJ 4400 AB (11041-6122), being of 9.7 and
12.8 arcsec. However, since 1924 no companion has since been seen. It
was not visible in 30cm.
Open cluster diameter is estimated as 13.6±2.2 pc., age is
437 Myr. and whose total mass is 126 M⊙. Distance is 1.44
kpc.
Reference to NGC 3496 & NGC 3519
- Piskunov, A.E., et al., “Tidal
Radii and Masses of Open Clusters.”, A&A., 477, 165
(2008)
Last Update : 27th February 2012
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(2012)
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