The N214C Nebula

An Emission Nebula, Containing a Rare Feature, Resides in a Nebulae Complex Tens of Thousands of Light Years Away From Us

Well, do not be afraid of the strange name of this object. It is, after all, an NGC nebula that any observer can detect when observing from the Southern Hemisphere even with telescopes as small as 8-inch of aperture.

Figure 1. The position of N214 in the Large Magellanic Cloud. North is up.

N214C1 (also NGC 2103, DEM L2 293, and MCELS L367) is an emission nebula included in the catalog of LMC emission nebulae published in 1956 by Karl Henize. This object was originally discovered by John Frederick William Herschel in 1834. With an estimated visual magnitude of 10.8, it is the brightest portion of a bigger nebula complex-N214-situated about 2° 15ʹ south of 30 Doradus, the most conspicuous nebular structure in our neighboring galaxy, the Large Magellanic Cloud. N214 is one of the southernmost complexes in our satellite galaxy, lying south of the stellar bar of that galaxy. It is a remarkable ongoing star-forming region containing at least 8 components, most of them very faint (see Figure 2) according to F. Meynadier, M. Heydari-Malayeri, and N R. Walborn in their paper “The LMC HII region N214C and its peculiar nebular blob”. This nebula holds the OB association3 LH 110 (Lucke & Hodge).

Most of the components are out of the reach of an 8-inch telescope, with N214C being the biggest and brightest portion by far, thus being visible through that kind of optical instrument.

At 42x, this object is clearly visible even without any nebular filter, looking like a slightly north-south elongated nebulosity of smooth brightness. A more detailed observation makes possible to detect, for moments, some brighter dots within it. Through a UHC filter, N214C is, undoubtedly, a conspicuous nebula. The filter improves the contrast of this HII region. Its overall shape is slightly elongated and its western edge looks a little less bright than the rest of this nebula (see lower panel on Figure 2).

Figure 2. The N214 complex (upper panel)

and the N214C nebula (lower panel) with

its two features. DSS image. North is up,
East to the left.

78x – At this magnification, N214C appears somewhat elongated ( overall oval shape of N214C) and some stars members of the OB association LH110 start to be discerned. These faint stars, embedded in the smooth nebulosity, have a longitudinal distribution coincident with the elongated direction of the HII region. In the central area of the nebula the brightest star of the whole object can be glimpsed, Sk -71°514, which is the main exciting source of the HII region and, in fact, is not a single star but a compact cluster (Garmany & Walborn 1987). It has at least 6 members (massive stars) in an area 4" wide. 

Using a UHC filter the view of N214C is interesting, being noticeable against the background sky with its shape being slightly elongated. An inner brighter zone containing at least one star or bright dot is visible at this power for moments using averted vision. This zone seems to have a slight elongation and its edges look somewhat fainter, with one of them appearing wider than the other. Orion Ultrablock filter helps to see the entire nebula more detached but it is not as useful as the UHC.

At 106x, N214C is an evident nebula at this higher power, appearing slightly oval in shape and showing a star-type feature in its central part matching with the position of the aforementioned stellar cluster SK-71°51. On the north-northwest corner of the nebula (see Figure 2) what seems to be a very small nebulosity, fainter than the central cluster, can be glimpsed with averted vision, with a relative position with the Sk cluster almost parallel to the three stars took as reference (linked to each other with white lines on Figure 2). The opposite region, the southern zone of the nebula, looks narrower.

Through a UHC filter, this part of the nebulae complex looks pretty detached from the background sky. Some dark areas seem to be present within N214C, jumping to the view when is observed at this power. For moments, SK -71°51 also clearly jumps to the view. 

Figure 3. HEB in N214C. Photo by ESO

At 146x, N214C looks  elongated with SK -71°51 being clearly visible even with direct vision. More difficult to see (averted vision is necessary) is the stellar-shaped feature in the north-northwest region. That object matches with the position of the most remarkable feature of N214C (labeled as HEB5 on Figure 2), a globular blob of ionized gas at ∼60" (∼15 pc) north of Sk −71◦51 to which attention was drawn by Walborn et al. (2002). In photographs like that taken by ESO, it appears as a sphere split into two lobes by a dust lane (see Figure 3) which reminds me of a small version of the Centaurus A galaxy. The Blob`s mass would be ∼100 Mʘ. It appears as a sphere about four light-years across. Do not expect to see anything remotely similar to that through an 8-inch telescope though. The compact HII region discovered in N214C may be a newcomer to the family of HEBs (High Excitation Blobs) in the Magellanic Clouds, the first member of which was detected in LMC N159 (Heydari-Malayeri et. al.). The H II blob coincides with a strong infrared source, 05423-7120, which was detected with the IRAS satellite. 

The view with UHC filter shows N214C more round than the view without this filter. The sight through the Orion Ultrablock filter seems to be better than that through UHC at this high magnification.

Bigger telescopes will surely show more features of the N214C nebula and more subtle details on the features visible with smaller telescopes. 

Figure 4. DSS image

How to find N214

This complex lies in constellation Mensa, an inconspicuous group of stars between constellations Hydrus, Volans, and Dorado that are easier to identify in the summer nights from the Southern Hemisphere.

Figure 4 shows a 1-degree field of view centered on N214 (R.A. 05 40 54   Dec. -71 14 42), about 2° 15ʹ south of 30 Doradus as I said before. As you can see, N214 is, by far, the most prominent feature there. The other components of the complex, situated upper right of N214C in the DSS image here (i.e. N214A, B, D, E, F, G, H), and see in more detail on Figure 5, where the 7 faint components of the N214 HII complex are labeled, are targets for owners of big mirrors and/or astrophotographers. The positions of the components in Figure 5 were taken using data from the SIMBAD Astronomical Database.

If you have the opportunity of observing this small nebula immersed in our satellite galaxy in a clear and dark summer night from any place in the Southern Hemisphere, remember that some peculiar features reside in the depths of this deep sky object.

Figure 5. DSS image

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1_ LHa-120 N is the full name of an entry in the Henize catalog of LMC emission nebulae. "L" refers to the Lamont-Hussey Observatory of the University of Michigan; "Ha" means the Hydrogen-alpha emission line, the key signature line used in the survey; "120" refers to the plate number (objective prism plate) for the LMC; "N" labels the object as a nebula, as distinct from a star (label "S").

2_ DEM is a catalog of 357 nebulae in the Large Magellanic Cloud and 167 nebulae in the Small Magellanic Cloud that was published in 1976 by R.D. Davies, K.H. Elliot, and J. Meaburn. The LMC catalog is DEM L and the SMC catalog is DEM S.

3_ The concept of a stellar association was originally introduced in 1949 by V. A. Ambartsumian, who later separated them into OB and T associations (Ambartsumian 1968). Morgan, Sharpless, & Osterbrock (1952) considered as a stellar association any loose group of stars within an area where bright OB stars exist and with evidence of a common origin.

A recent definition of a stellar association (Kontizas et. al. 1999) refers to it as a single, unbound concentration of early-type luminous stars, embedded in a very young star-forming region.

4_ Sk-71◦51 is the abbreviation of Sanduleak -71◦51. The American astronomer Nicholas Sanduleak published an important list of objects (stars and nebulae showing emission lines in their spectra) in the Magellanic Clouds in 1970. The “-71” in the name is the declination of the object, while the “51” is the entry number in the catalog.

5_ HEB (High-excitation blobs) are very dense, small regions (∼4 00, to 1000, in diameter corresponding to ∼1–3 pc)that are often observed lying adjacent or projected onto giant HII regions and are younger than the associated giant HII regions.