Planetary Nebula Of The Week - 7

**   NGC 2346 **

= Minkowski 1-10 =

CONSTELLATION OF MONOCEROS (The Unicorn)

NGC 2346 Imaged By Frank Loch

 NGC 2346 in Monoceros. This tri-color image was taken on 03/16/98. The lx200 12" was at f/10, and the ST7 (18micron) camera was attached to the AO7 adaptive optics device. The three exposures were: Red -- 2400 seconds, green-- 2400 seconds, and blue -- 2, co - added, each @ 1800 seconds. Each of the three images was dark subtracted and flat fielded in CCDSoft. They were each subjected to 1 cycle of 5 deconvolutions in CCDSharp. Photoshop was used to color combine and color balance the three images.

Images From Space And Earth

Hubble Space Telescope Image	Digital Sky Survey Image (SkyView)

PHOTO RELEASE NO.: STScI-PRC97-07

Hubble Camera Resumes Science Operation With Picture Of "Butterfly" In Space.

The Hubble Space Telescope's Wide Field and Planetary Camera 2(WFPC2) is back at work, capturing this black-and-white image of the "butterfly wing"-shaped nebula, NGC 2346. The nebula is about 2,000 light-years away from Earth in the direction of the constellation Monoceros.  It represents the spectacular "last gasp" of a binary star system at the nebula's center.

The image was taken on March 6, as part of the recommissioning of the Hubble Space Telescope's previously installed scientific instruments following the successful servicing of the HST by NASA astronauts in February.  WFPC2 was installed in HST during the servicing mission in 1993.

At the center of the nebula lies a pair of stars that are so close together that they orbit around each other every 16 days. This is so close that, even with Hubble, the pair of stars cannot be resolved into its two components.  One component of this binary is the hot core of a star that has ejected most of its outer layers, producing the surrounding nebula. Astronomers believe that this star, when it evolved and expanded to become a red giant, actually swallowed its companion star in an act of stellar cannibalism. The resulting interaction led to a spiraling together of the two stars, culminating in ejection of the outer layers of the red giant.

Most of the outer layers were ejected into a dense disk, which can still be seen in the Hubble image, surrounding the central star.  Later the hot star developed a fast stellar wind.  This wind, blowing out into the surrounding disk, has inflated the large, wispy hourglass-shaped wings perpendicular to the disk. These wings produce the butterfly appearance when seen in projection.

The total diameter of the nebula is about one-third of a light-year, or 2 trillion miles.

Our own Sun will eject a nebula about 5 billion years from now. However, the Sun is not a double star, so its nebula may well be more spherical in shape.

The image was taken through a filter that shows the light of glowing nitrogen atoms.

Credit: Massimo Stiavelli (STScI), and NASA; other team member: Inge Heyer (STScI)

(Editor's note: Although NASA refers to this planetary as 'Butterfly', the planetary that already has this common name is a planetary in Ophiuchus designated M2-9)

Location Chart  From 'MegaStar, Version 4.0'

Additional Factinos:

• Distance: Estimated to be 2,000 light years from our solar system.
• Radial Velocity: 22 km/sec, moving away from our solar system.
• Expansion Velocity: Approximately 40 km/sec.
• Discovered by Minkowski, 1946
• Uranometria 2000.0 Chart No. 228
• NGC/IC description is ' *10 att with S, vF, neb ' (Star, mag 10 attached with Small, very        Faint nebula).
• Central star is an eclipsing binary, V651Mon. (Information follows)

     

NGC 2346 IMAGED FROM Anglo-Australian Telescope	NGC 2346 IMAGED FROM KITT PEAK NATIONAL OBSERVATORY

  OBSERVATION NOTES

Steve Gottlieb:
N2346 = PK 215+3 1
07 09.4 -00 48
13": bright mag 11.5 central star surrounded by fairly small, round disc.
Located between two mag 13 stars 0.8' E and 1.2' W.  View enhanced with
Daystar 300 filter.  Central star is the variable V651 Mon (mag 11.3-13.5).
 
     

NGC 2346 FILTERED IMAGES

OIII	COMPUTER MODEL
H-ALPHA	NITROGEN II

---

 

Central Star of NGC 2346

V651 Mon

(The following text and next two images are courtesy Kyoto University)
On the fading (vsnet-alert 550)  

V651 Mon is a binary central star of the planetary nebula NGC 2346. The 15.991-day binary consists of an A5V starand a hot (Te ~ 10^5K) subdwarf. This binary has received special attention since its fading (or eclipsing) episode starting in 1981 (Kohoutek 1982). The fadings recurred with the orbital period. Subsequent observations lead to a picture of a passing cloud in front of the binary: eclipses in the visual light occur when the orbiting A5V star passes behind the cloud (a good review article: Costero et al. 1986, Rev. Mexicana Astron. Astrof. 13, 149). Costero et al. expects from the amount of the dust from IRAS observations that the probability of such passages are very rare. In fact plate searches could not detect any similar events between 1899 and 1981.

Since the present fading episode may provide a unique chance in probing dust condensations (or planetesimals) around highly evolved stars (recall the recent fine images of such bodies in NGC 7293 by HST), observations in all wavelengths are urged. From the epoch of the fading by D. Overbeek, the next eclipse in the visual light will occur around Oct. 11. The UV eclipses will occur 8 days before and after this.

Regards, Taichi Kato  

Recent Light Curve of V651 Mon

       

 

 

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03/08/ 98