Talk:Planetary nebula

message: In the opening section of the article, the mention of Darquier is interesting but not relevant. The prominence given to Darquier is misleading and the passage should be removed, or shortened and moved. Three sources are cited for the Darquier quotation; it is actually found in Messier's "Catalogue des Nébuleuses & des amas d'Étoiles" in the Connoissance des Temps
(https://books.google.co.uk/books?id=-NnBsQU7QdgC&pg=PA259). Messier remarks on his entry number 57:
M. Messier a rapporté cet amas de lumiere sur la carte de la comète de 1779. M. Darquier, a Toulouse, découvrit cette nébuleuse, en observant la même comète, et il rapporte: “Nébuleuse entre gamma & beta de la Lyre; elle est fort terne, mais parfaitement terminée; elle est grosse comme Jupiter et ressemble à une planète qui s’éteindroit.”
There is no evidence that Darquier's remark (or Messier 57 itself) influenced the subsequent introduction of the term "planetary nebula" by William Herschel who explained the name in his paper, “On the Construction of the Heavens” [Phil. Trans., vol. lxxv., 1785, pp. 213-266.] At the time he believed that all nebulae consisted of unresolved stars, glowing in the manner of the Milky Way. He did not consider Messier 57 planetary; his prototypes for the class were NGC 7009 (the very first DSO he discovered, nicknamed the Saturn Nebula by Rosse in the 1840s) and NGC 7662 (nicknamed the “Blue Snowball” in the 1960s). Here are extracts from Herschel’s paper:
A Perforated Nebula, or Ring of Stars.
Among the curiosities of the heavens should be placed a nebula, that has a regular, concentric, dark spot in the middle, and is probably a Ring of stars. It is of an oval shape... The light is of the resolvable kind, and in the northern side three very faint stars may be seen, as also one or two in the southern part... It is the 57th of the Connoissance des Temps. Fig. 5 is a representation of it.
Planetary Nebulae.
I shall conclude this paper with an account of a few heavenly bodies, that from their singular appearance leave me almost in doubt where to class them. The first [NGC 7009, which Herschel discovered in 1782]... I have examined... with the powers of 71, 227, 278, 460, and 932; and it follows the laws of magnifying, so that its body is no illusion of light. It is a little oval, and in the 7-feet reflector pretty well defined, but not sharp on the edges. In the 20-feet, of 18.7 inch aperture, it is much better defined, and has much of a planetary appearance, being all over of an uniform brightness, in which it differs from nebulae: its light seems however to be of the starry nature, which suffers not nearly so much as the planetary disks are known to do, when much magnified. The second of these bodies [NGC 7662]... has a round, bright, pretty well defined planetary disk of about 12" diameter, and is a little elliptical... [Herschel then describes NGC 6369, NGC 6905, NGC 6984]. The planetary appearance of the two first [NGC 7009, NGC 7662] is so remarkable, that we can hardly suppose them to be nebulae; their light is so uniform, as well as vivid, the diameters so small and well defined, as to make it almost improbable they should belong to that species of bodies. On the other hand, the effect of different powers seems to be much against their light's being of a planetary nature, since it preserves its brightness nearly in the same manner as the stars do in similar trials. If we would suppose them to be single stars with large diameters we shall find it difficult to account for their not being brighter; unless we should admit that the intrinsic light of some stars may be very much inferior to that of the generality, which however can hardly be imagined to extend to such a degree. We might suspect them to be comets about their aphelion, if the brightness as well as magnitude of the diameters did not oppose this idea ; so that after all, we can hardly find any hypothesis so probable as that of their being Nebulae; but then they must consist of stars that are compressed and accumulated in the highest degree. If it were not perhaps too hazardous to pursue a former surmise of a renewal in what I figuratively called the Laboratories of the universe, the stars forming these extraordinary nebulae, by some decay or waste of nature, being no longer fit for their former purposes, and having their projectile forces, if any such they had, retarded in each others' atmosphere, may rush at last together, and either in succession, or by one general tremendous shock, unite into a new body. Perhaps the extraordinary and sudden blaze of a new star in Cassiopea's chair, in 1572, might possibly be of such a nature. But lest I should be led too far from the path of observation, to which I am resolved to limit myself, I shall only point out a considerable use that may be made of these curious bodies. If a little attention to them should prove that, having no annual parallax, they belong most probably to the class of nebulae, they may then be expected to keep their situation better than any one of the stars belonging to our system, on account of their being probably at a very great distance. Now to have a fixed point somewhere in the heavens, to which the motions of the rest may be referred, is certainly of considerable consequence in Astronomy; and both these bodies are bright and small enough to answer that end.
In 1790 he discovered NGC 1514 (a planetary nebula in the modern sense) and saw it as a "star with atmosphere". He then revised his theory, believing that some nebulae consisted of luminous fluid (possibly of planet-forming kind) rather than unresolved starlight. Many of the objects he classed as "planetary nebulae" (his Class IV) are really galaxies. — Preceding unsigned comment added by Andrew Crumey (talk • contribs) 
:Nope: Not true. Darquier, A. (1777) comments appear in his notebook, being Reference 3 in the article. This has been discussed several times on this Talkpage. It is evidence of perpetuated bias that has historically been mostly made by English writers. Sure Herschel tried to explain the phenomena of planetary nebulae, but the usage of the term predates this. Arianewiki1 (talk) 01:14, 20 March 2019 (UTC)
thread_title:  Herschel's invention and explanation of the term 

message: The planetary nebula known as PK 358-1.1, located at two degrees south of the galactic center, is also known as "BID" (so it is mentioned in THE DEEP SKY FIELD GUIDE TO URANOMETRIA 2000.0, chart 377). What is the meaning of "BID"? According to SIMBAD the BI must be Blanco, but... what is the "D"? Is it perhaps the fourth object (the D-object) in a catalogue from Blanco? DannyCaes (talk) 09:58, 22 January 2023 (UTC)
thread_title:  Odd nomenclature