Heart Nebula (IC 1805)
History
On 3rd November 1787, the German-British astronomer Wilhelm Herschel discovered a nebula in the constellation Cassiopeia, which he designated as WH III 695. John L. E. Dreyer included it in 1888 as NGC 896 in his «New General Catalogue of Nebulae and Clusters of Stars» and described it as follows: «very weak, rather large, irregular shape». In 1890 the American astronomer Edward Barnard photographed the same section of the sky and discovered a «foggy spot» a little northeast at the location noted for NGC 896, which John L. E. Dreyer unwittingly included in his second «Index Catalogue» as IC 1795 as a double entry for NGC 896. Presumably Herschel only saw the brightest western part of IC 1795. About one degree southeast of this nebula Barnard discovered another large nebula in which an open star cluster was embedded. This then became IC 1805. [196]
Physical Properties
All objects (NGC 896, IC 1795 and IC 1805) are connected to one another, large H-II area and form the «Heart Nebula», which is formed by the young O and B stars in the star cluster in IC 1805 (Collinder 26, Melotte 15) can be excited to glow. On Simbad a distance of 4.1 kpc (13'400 light years) is found for IC 1795. For IC 1805 one finds distances of 1.7 kpc to 6.1 kpc (around 5500 to 20'000 light years). The real distance is probably somewhere in between. [145]
About 2.5 degrees further west is another nebula, the «Soul Nebula» (Sharpless 2-199 with cluster IC 1848). Both nebulae are often referred to together as the «Heart and Soul Nebula».
| Name | RA | Dec | Type | bMag | vMag | B-V | SB | Dim | PA | z | D(z) | MD | Dreyer Description | Identification, Remarks |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NGC 896 | 02 25 27.8 | +62 01 10 | EN | 10 × 10 | 2.300 | eF, pL, iF | IC 1795, LBN 645, CED 6, SG 1.04, Min 2-57, narrrow dark lane n-s, SNR ? | |||||||
| IC 1795 | 02 25 27.8 | +62 01 10 | dup | 10 × 10 | 2.300 | Patch of neby | NGC 896, LBN 645, CED 6, SG 1.04, Min 2-57, narrrow dark lane n-s, SNR ? | |||||||
| IC 1805 | 02 32 48.0 | +61 27 42 | OCL (III3pn) | 6.5 | 20 | 1.886 | Cl, co, eL neby extends f | OCL 352, Mel 15, LBN 654 |
Finder Chart
The Heart Nebula is located in the constellation Cassiopeia. In Central Europe it is circumpolar. The best time to observe, however, is July to January, when the constellation is highest at night.
Visual Observation
Description pending ...