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Type: planetary nebula
Mag: B=?, V=?
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Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "faint, pretty large, round, gradually a little brighter in the middle; 80 arcseconds. At least 80 stars in the field."
Burnham summarizes this nebula as "pretty large, pretty faint, round, diameter 1.5', in rich field 1.3 southeast from Kappa Vel."
From: "Neat Southern Planetaries - XII"
This month we cover two planetaries in southern Vela, placed to the east of the asterism of the False Cross.
NGC 2899 / He2-30/ WRAY 16-47/ My 48/ Gum 27/ RCW 43/ PK277-3.8 (09214-5819) (Vela) was first discovered by Sir John Herschel in 1835. NGC 2899 is found in a moderately bright star field, found some 8'min.arc. west of the 7.6 magnitude star SAO 236965. The blue Kappa ( or ) Velorum (Markab or Markeb) is the nearest bright star (Mag. 2.6), which is the most easterly star in the False Cross. Culminating at midnight on the 26th March each year, taking the mid point between Kappa Velorum and the orange N Velorum easily finds the planetary. (2.7O SE from Kappa Vel). Using a 20cm., it took me less than thirty seconds to find the object. NGC 2899 does not appear in Sky Atlas 2000.0, but does appear listed in the Catalogue. However, they correctly identify it in Uranometria 2000.0.
At visual magnitude 11.8, a 15cm will show the planetary plainly, with a 25cm. or greater starting to show some structural details. They state a photographic magnitude in some sources to be between 9.7 and 12.2, with the later perhaps being closer to the truth. Unlike some planetaries, this object improves with magnification.
The structure of this planetary is unusual, and though they give no classification of structure, the photographic images show that it might be anomalous - a possible Vorontsov-Velyaminov Type VI (6). However, visually it appears closer to a Type IV! My first observation was made during particularly bad seeing, and the visibility of the outer edges or of the mottling within the nebulosity was impossible. My next session showed a vast improvement, as the night was so good, that at 420X I could still see the faint hole in the centre. An O-III filter made the hole appear prominent, and in all, vastly improved the structures within the nebulosity. I was surprised to be able to see this 'hole', as only a few observers have claimed to see it using apertures above 30cm.
The edges to me looked unusually uneven, especially to the east and north, and in some ways even reminded me of NGC 5189 in Musca or even NGC 5844 in Triangulum Australe. Throughout the literature, it seems that it is overall structural quite different. AOST2 states;
"... It is an irregularly oval luminous planetary nebula about 1.5' across, of rather uneven light and showing its emission nature by its single prism image."
According to the AAO website, David Malin took the colour image using three separate plates at 385nm., 495nm. and 630nm. Each exposure of NGC 2988 was taken for 30 minutes, and combined into a single image. Listed as A beautiful colour image of AAO Slide #109, also appears in AOST2 as Plate 61.
I thought that the nebulosity appeared yellowish - and this is quite different other planetaries discussed in this series. There seems quite a difference between the visual and photographic images. Visually it appears to me as a mottled annular disk, which is brightest at PA 40O. Averted vision help discerns the appearance of the mottling, showing that the surface is uneven. Photographs show a more square or 'chair-like' structure, that some claim to think is more like an 'abstract' butterfly.
In size, the nebula covers about 90"sec.arc., though some sources say 110"sec.arc. Deep sky photographs, show the edges extend to a maximum of c.120"sec.arc.
Doubt was expressed of the planetary nature of this object in 1968. To quote Hartung in AOST2;
" This object is not listed either as a planetary or a diffuse nebula, and little seem to be known about it." and "...and the position and gaseous character show that it must be a galactic object."
The only star atlas I could find which had NGC 2899 mapped and listed was Verenberg-Blank's 'Handbook of the Constellations.', but it gives it as a diffuse nebula. The planetary nature of this object was first suggested by Henize in 1964, but we did not accept this until the mid-1970's. Looking at the images and the spectral profile, there is a strong red N II emission (at 658.4nm.), and no doubt the reason that NGC 2899 was first mistaken for a small emission nebula. Unlike the 90% of planetaries in colour photos that appear blue or greenish, this one is red. (Interestingly, this single N II line is also prominent in the red colour seen in some aurorae.) Readers may like to compare this spectral profile with other profiles seen in this series in the last month or two.
To improve contrast, observers with apertures >30cm. may like to attempt to use a light red filter on this object. Perhaps this may also reveal the 'butterfly' structure seen in the astrophotos.
Based on the nitrogen emissions, the literature states (Ie. IAU Symposium No.103; Peimbert and Torres-Peimbert (1983)) that NGC 2899 may be a candidate of a bipolar planetary Type I with extreme filamentary structure. They currently know only twenty-nine of these objects.
The central star is invisible to all amateur telescopes - even using a direct vision prism. ESO-Strasbourg catalogue states that the visual magnitude of the PNN is >15.9, while the photographic magnitude is >16.4. Temperature determination of the core star is difficult because of the lack of Helium lines; so a Zanstra temperature cannot be given.
NGC 2899 is approaching us at 3.0 kms-1 towards us, while the nebulosity is expanding at c.+25kms-1.
Statistical distances are estimated at 1.03± 0.3 kpc, and this even this is particularly uncertain.
In all, this planetary is easy to find and is a worthy object for moderate apertures.
Chopinet, M. & Lortet-Zuckermann, M.C. (1972) A note to designations of planetary nebulae. Astron.Astrophys., 18, 166-167.
NGC 2899: He 2-30, My 48, PK 277-3°1, RCW-43.
The RNGC (Sulentic and Tifft 1973) notes that this is a planetary nebula.
Hartung writes: "This field is lovely, sown with fairly bright stars on a profuse faint background. In it is an irregularly round luminous haze about 1.5' across, rising broadly to the centre...a 6-inch telescope will show the nebula but its location needs care."
QBS: *s 1'.2 (10"; pa315), 1'.2 W (11"; pa85), 1'.15 S, and 1'.25 ENE also a wide pair). closer of two SW 40" is nr edge of neb; also 45" SE. brtr wedges of neb NE & SW of cen *, brtst on SW.
15cm - lg and fairly losfcbr, but obvious @ 80x; m11.5-12. mod broad cen brtning. m13.5-15.5 *s at all cardinal points and on SE & NW; ones W & N are pairs. * SW is closest and gives reasonable measure of edge. 140x and 195x show diffusely bordered patch w/wk mottling, notably brtr area on W side. 195x shows m15.5 cen * nr center consistently, although not certainly. fun object! oh yeah: Deep Sky filter very good here even @ 195x; UHC and [OIII] not dramatically better. BS, 21Feb1990, LCO.
8-inch Dobsonian f/5 (EP: 25mm 48x)
Conditions: Clear, dark.
Midway between N and kappa is the planetary nebula NGC 2899. At 48x and 96x the nebula is readily visible, appearing as a pretty faint, pretty large, irregularly round glow. The delicate nebula is noticeably bounded by four 12th magnitude stars, as if they are staking it out and have pinned it down. Ten arcminutes north-northwest of the nebula lie two 8th magnitude stars (SAO 236986 and SAO 236985) – the nebula appears slightly larger than the separation between these two, so I'd peg it at 1.5-arcminutes in diameter. As is often the case with objects that have detail that is at the limit of one's ability to see (or at least, at my limit, and particularly with round-ish objects), the initial impression of a round shape becomes less certain. I start "sensing" all sorts of slightly elliptical shapes instead, but the orientation refuses to remain constant. So with NGC 2899 in the 8-inch tonight – I eventually cautiously settled for an ever so slightly elongated outline, oriented roughly north-south.
1998-01-26/27, 6-inch f/8.6 Newtonian, Stellenbosch Rifle Range site. Dew. Several small 10th mag stars seen hereabouts. Cannot clearly identify the planeb, since the eyepiece dew makes small halos common.
1994-02-06, Die Boord, 11x80's tripod-mounted. I think, at times, I see a very faint star here.
One one occassion, I was observing with the 15.5-inch at 200x. My log reads: "At exact spot on map is a pretty bright 9-10th mag star, which forms an isoceles triangle with the apex an 8th mag star lying west and slightly south of it. The third star of the triangle, on the base of the triangle, lies almost due north of the planetary. North of this star is a bright pair of slightly reddish stars. This bright pair and the apex is shown on the Uranometria chart 425. The plantary appears stellar, no disc seen."
12-inch f/10 SCT (346x)
The planetary was easily seen between a field of view scattered with stars. Two faint lobes defined in the north-south direction. High power reveals a lot of detail, showing a round hazy north-eastern side and well define south-western edge. Although it is been cut off in a way closer investigation show a small dent in the edge. More info in my files.
16-inch f/10 SCT (127x, 290x)
Soft glow amongst a splash of stars around it. It shows a more rounder soft hazy edge towards the west, and less define to the south-east, with averted vision the long thin opening from north to south could clearly be seen. The field is very busy ecclesial towards the north.
The Messier objects
The Bennett objects
The Caldwell list
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