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[M 57]

Messier 57

Observations and Descriptions

Discovered by Antoine Darquier de Pellepoix in January, 1779.
Discovered independently by Charles Messier on January 31, 1779.

Messier: M57.
January 31, 1779. 57. 18h 45m 21s (281d 20' 08") +32d 46' 03"
"A cluster of light between Gamma & Beta Lyrae, discovered when looking for the Comet of 1779, which has passed it very close: it seems that this patch of light, which is round, must be composed of very small stars: with the best telescopes it is impossible to distinguish them; there stays only a suspicion that they are there. M. Messier reported this patch of light on the Chart of the Comet of 1779. M. Darquier, at Toulouse, discovered it when observing the same comet, and he reports: "Nebula between gamma and beta Lyrae; it is very dull, but perfectly outlined; it is as large as Jupiter & resembles a planet which is fading"."

[From: Memoir on the Comet of 1779, Mem. Acad. for 1779, p. 318-372 + Pl. XIV. Messier's discovery announce of M57, p. 320]
On January 31 [1779] in the morning. [..] When comparing in this morning the Comet [C/1779 A1 Bode, Messier's 17th comet] with Beta in Lyra, I have perceived with the refractor a small cluster of light, which has appeared to me to be composed of very small Stars, which one could not distinguish with the instrument: This rounded cluster of light was placed between Gamma & Beta Lyrae. On September 3, I have once more examined that light with an achromatic refractor, which I had made to magnify about 120 times; I could not recognize, as for the first time, if it was composed of small Stars: here is its position; I have also reported it on the Chart of the apparent route of the Comet.

  Nebula                                Right           Northern
  between Gamma and Beta Lyrae          Ascension       Declination
  
January 31, 1779 in the morning 281d 20' 8" 32d 46' 3"
[p. 352]
RA: 281.20. 8, Dec: 32.46. 3 N, No. 11. In Lyra, discovered January 31, 1779.

Darquier
[Supplement zu Flamsteads Sternverzeichnis.. von Herrn Darquier zu Toulouse (Supplement to Flamstead's star catalog .. by Mr. Darquier of Toulouse). Astronomisches Jahrbuch für das Jahr 1784, p. 190-200, here p. 199]
RA 281d 20' 50" (18h 45m 19s), Dec 32d 45' 59" N, Nebula
This nebula, to my knowledge, has not yet been noticed by any astronomer. One can only see it with a very good telescope, it is notresembling any of those [nebula] already known; it has the apparent dimension of Jupiter, is perfectly round and shrply limited; its dull glow resembles the dark part of the Moon before the first and after the last quarter. Meanwhile, the center appears a bit less pale than the remaining part of its surface.

Bode [1781]
[Supplement zu Flamsteads Sternverzeichnis.. von Herrn Darquier zu Toulouse (Supplement to Flamstead's star catalog .. by Mr. Darquier of Toulouse). Astronomisches Jahrbuch für das Jahr 1784, p. 190-200, here p. 199]
I have clearly seen this nebula between Beta and Gamma in Lyra, which was not yet known to now, in the night between August 27 and 28 of this year [1781] for the first time with a 3-foot [FL] Dollond telescope.

William Herschel
[1785. PT LXXV=75 (1785), p. 213-66, here p. 263. Reprinted in: Scientific Papers, Vol. I, p. 257]
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 shorter axis being to the longer as about 83 to 100; so that, if the stars form a circle, its inclination to a line drawn from the sun to the center of this nebula must be about 56 degrees. The light is of the resolvable kind [i.e., mottled], and in the northern side three very faint stars may be seen, as also one or two in the southern part. The vertices of the longer axis seem less bright and not so well defined as the rest. There are several small stars very bear, but none seems to belong to it. It is the 57th of the Connoissance des Temps [Messier's catalog]. Fig. 5 is a representation of it.

[PT 1814, p. 261, SP2 p. 527]
Connoiss. 57 [M 57 = NGC 6720] is "An oval nebula with an eccentric oval dark space in the middle; there is a strong suspicion of its consisting of stars. The diameter, measured by the large 10 feet, is 1'28".3."

[PT 1818, p. 445, SP2 p. 599]
The 57th of the Connoissance. [M 57 = NGC 6720]
"1782, 7 feet telescope. I suspect it to consist of very small stars; in the middle it seems to be dark."
"1783, 1805, 1806, 10 feet telescope. With 130 it seems to be a rim of stars, but with 350 there remains a doubt. It is a little oval; the dark place in the middle is also oval; one side of the bright margin is a little narrower than the other."
"1784, 1799, 20 feet telescope. It is an oval with a dark place within; the light is resolvable. 240 showed several small stars near, but none that seems to belong to it. It is near 2 minutes in diamter."
"1805, large 10 feet telescope. By a meridian passage of 7 seconds of siderial time, the diameter is 1' 28".4."
By the observation with the 20 feet telescope, the profundity of the stars of which it probably consists must be of higher than 900th order; perhaps 950.

John Herschel (1833): h 2023.
h 2023 = M57.
Sweep 198 (August 1, 1829)
RA 18h 47m 13.2s, NPD 57d 10' 37" (1830.0) [Right Ascension and North Polar Distance]
The annular nebula in Lyra. The diameter of the ellipse in R.A. = 6s.5:: It has a small star f exactly on the parallel of the centre, and distant from the edge rather more than the breadth of the ring.
The annular nebula in Lyra. The diameter of the ellipse in R.A. is 6.5s :: [unsure value]. It has a small star following [East of] exactly on the parallel of the centre, and distant from the edge rather more than the breadth of the ring.

Sweep 197 (July 31, 1829)
RA 18h 47m 13.4s, NPD 57d 11' 7" (1830.0)
Annular neb. between Beta and Gamma Lyrae. Pos of longer axis of annulus = 57deg.0 by microm. The small * f is almost exactly on the parallel of its centre, dist about = breadth of the ring. The central vacuity is not black; a nebulous light fills it. The edges are not sharply cut off, very slightly ill defined. See fig. 29.
Annular nebula between Beta and Gamma Lyrae. Position angle of longer axis of annulus is 57.0 deg by micrometer. The small [faint] star following is almost exactly on the parallel of its centre, distance about the same as the breadth of the ring. The central vacuity is not black; a nebulous light fills it. The edges are not sharply cut off, very slightly ill defined. See fig. 29.

Sweep 199 (August 5, 1829)
RA 18h 47m 17.6s ::, NPD 57d 11' 31" (1830.0)
R.A. not good, the sweeping zero having been interrupted by the disturbing effect of the side motion in viewing object.

Sweep 168 (August 19, 1828)
NPD 57d 13' +/- (1830.0)
No RA, very rough PD; viewed; diameter in RA = 5s.375 by a mean of 4 careful obs. The star following it = 11m. It follows the centre by 4s.31, and its pos from the centre = 96deg.4 by microm. The neb has a mottled look. [N.B. The mottled look, however, is something quite different from the appearance called resolvable.]
No RA, very rough PD; viewed; diameter in RA is 5.375 s by a mean of 4 careful observations. The star following it is of 11th magnitude. It follows the centre by 4.31s, and its position angle from the centre is 96.4 deg by micrometer. The nebula has a mottled look. [N.B. The mottled look, however, is something quite different from the appearance called resolvable.]

[Appendix]

[Figure on Plate X, Figure 29, No. 2023, M. 57, RA 18h 47m 13s, NPD 57d 11']

Fig. 29. Mess. 57. - An annular nebula in Lyra. It is ill represented. The edges exhibit a curdled and confused appearance, like stars out of focus. The interior is far from absolutely dark. It is filled with a feeble but very evident nebulous light, which I do not remember to have seen noticed by former observers. Comparing figures 25 [M51], 27 [M64], 28 [H V.19, NGC 891], 29 and 48 [H 4. 13, NGC 6894], it will appear that the annular form, or an approach to it, is one of those which nebulae affect, and taken in connexion with the ring of Saturn or the Milky Way, may lead us to conceive some kind of analogy, however obscure, may subsist in all those cases.

Smyth: DCLXIX [669]. M57.
DCLXIX. 57 M. Lyrae.
AR 18h 47m 37s, Dec N 32d 50'.1
Mean Epoch of Observation: 1835.57 [Jul 1835]
[with drawing]
This annular nebula, between Beta and Gamma on the cross-piece of the Lyre, forms the apex of a triangle which it makes with two stars of the 9th magnitude; and its form is that of an elliptic ring, the major axis of which trends sp to nf [SW to NE]. This wonderful object seems to have been noted by Darquier, in 1779; but neither he nor his contemporaries, Messier and Méchain, discerned its real form, seeing in this aureola of glory only "a mass of light in the form of a planetary disc, very dingy in colour." Sir W. Herschel called it a perforated resolvable nebula, and justly ranked it among the curiosities of the heavens. He considered the vertices of the longer axis less bright and not so well defined as the rest; and he afterwards added, "By the observations of the 20-feet telescope, the profundity of the stars, of which it probably consists, must be of a higher than the 900th order, perhaps 950." This is a vast view of the ample and inconceivable dimensions of the spaces of the Universe; and if the oft-cited cannon-ball, flying with the uniform velocity of 500 miles an hour, would require millions of years to reach Sirius, what an incomprehensible time it would require to pass so overwhelming an interval as 950 times the distance! And yet, could we arrive there, by all analogy, no boundary would meet the eye, but thousands and ten thousands of other remote and crowded systems would still bewilder the imagination.
In my refractor this nebula has a most singular appearance, the central vacuity being black, so as to countenance the trite remark of its having a hole through it. Under favourable circumstances, when the instrument obeys the smooth motion of the equatoreal clock, it offers the curious phenomenon of a solid ring of light in the profundity of space. The annexed sketch affords a notion of it.
Sir John Herschel, however, with the superior light of his instrument, found that the interior is far from absolutely dark. "It is filled," he says, "with a feeble but very evident nebulous light, which I do not remember to have been noticed by former observers." Since Sir John's observation, the powerful telescope of Lord Rosse has been directed to this subject, and under powers 600, 800, and 1000, it displayed very evident symptoms of resolvability at its minor axis. The fainter nebulous matter which fills it, was found to be irregularly distributed, having several stripes or wisps in it, and the regularity of the outline was broken by appendages branching into space, of which prolongations the brightest was in the direction of the major axis.

Lord Rosse
[Phil. Trans. 1844, p. 321-324, drawing on plate XVIII, Fig. 29; on his observation with his 3-feet (36-inch) aperture telescope]
The annular nebula in Lyra; 2 is the star in Sir John Herschel's sketch; I have inserted the six other stars as in some degree tests of the power of a telescope. Near star 3 there are two very minute stars seen with great difficulty; the others are easily seen whenever the night is sufficiently good to show the nebula well. The filaments proceeding from the edge become more conspicuous under increasing magnifying power within certain limits, which is strikingly characteristic of a cluster; still I do not feel confident that it is resolvable. I am however disposed to think that it was never examined when the instrument was in as good order , and the night as favourable, as on several occasions when the resolvable character of fig. 26 [M27] was ascertained. [Actually neither of these nebulae is resolvable into stars -hf]

Webb
The only annular neb. accessible by common telescopes, fortunately easily found, 1/3 of the distance from Beta towards Gamma [Lyrae]. It is somewhat oval, and bears magnifying well. Its light I have often imagined fluctuating and unsteady, like that of other plan. neb.; an illusion arising probably from an aperture too small for the object.

John Herschel, General Catalogue: GC 4447.
GC 4447 = h 2023 = M57; D'Arquier.
RA 18h 48m 20.1s, NPD 57d 8' 57.2" (1860.0) [Right Ascension and North Polar Distance]
!!!; Annular Nebula; B; pL; cE (in Lyra). 14 observations by W. & J. Herschel.
Magnificient; annular shaped nebula; bright; pretty large; considerably extended [elongated] (in Lyra).
Remark: Figures in: P.T. 33 [J.H. 1833], plate ii, fig. 29; P.T. 44 [Lord Rosse 1844], plate xix, fig. 29 (*); D'Arr. [M. D'Arrest's Inaugural dissertation and description of the Copenhagen Equatorial, 1861], plate ii, fig. 5.
(*) No. 4447, P.T. 44, xix, fig. 29. There is an error in this figure. For Decl. 32 deg 49' n read 22deg 49' n.

Huggins
[On the Spectra of some of the Nebulae. Phil. Trans. Roy. Soc., Vol. 154 (1864), p. 437-444; here p. 440]
[No. 4447. 2023 h. 57 M. R.A. 18h 48m 20s. N.P.D. 57d 8' 57".2. An annular nebula; bright; pretty large; considerably elongated.] In Lyra (+).
The apparent brightness of this nebula, as seen in the telescope, is probably due to its large extent, for the faintness of its spectrum indicates that it has a smaller intrinsic brightness than the nebulae already examined. The brightest of the three lines was well seen. I suspected also the presence of the next in brightness. No indication whatever of a faint spectrum. The bright line looks remarkable, since it consists of two bright dots corresponding to sections of the ring, and between them was not darkness, but an excessively faint line joining them. This observation makes it probable that the faint nebulous matter occupying the central portion is similar in constitution to that of the ring. The bright line was compared with the induction-spark (++).
(+) Lord Rosse, in his description of this nebula, remarks, "The filaments proceeding from the edge become more conspicuous under increasing magnifying power within certain limits, which is strikingly characteristic of a cluster; still I do not feel confident that it is resolvable." - Philosophical Transactions, 1844, p. 322 and Plate XIX, fig. 29.
In 1850, Lord Rosse further remarks, "I have not yet sketched it with the 6-feet instrument, because I have never seen it under favourable circumstances: the opportunities of observing it well on the meridian are comparatively rare, owing to twilight. It was observed seven times in 1848, and once in 1849. The only additional particulars I collect from the observations are that the central opening has considerably more nebulosity, and there is one pretty bright star in it, s. f. the centre, and a few other very minute stars. In the sky round the nebula and near it there are several very small stars which were not before seen; and therefore the stars in the dark opening may possibly be merely accidental. In the annulus, especially at the extremities of the minor axis, there are several minute stars, but there was still much nebulosity not seen as distinct stars." - Philosophical Transactions, 1850, p. 506.
"Nothing additional since 1844, except a star s. f. the middle." - Philosophical Transactions, 1861, p. 732.
(++) Already in 1850 Lord Rosse had discovered a connexion in general plan of structure between some of the nebulae which present small planetary disks in ordinary telescopes, and the annular nebula in Lyra. His words are, "There were but two annular nebulae known in the northern hemisphere when Sir John Herschel's Catalogue was published; now there are seven, as we have found that five of the planetary nebulae are really annular. Of these objects, the annular nebula in Lyra is the one in which the form is the most easily recognized." - Philosophical Transactions, 1850, p. 506.

[p. 442]
It is obvious that the nebulae 37 H IV (NGC 3242), Struve 6 (NGC 6572), 73 H IV (NGC 6826), 1 H IV (NGC 7009), 57 M, 18 H. IV (NGC 7662) and 27 M. can no longer be regarded as aggregations of suns after the order to which our own sun and the fixed stars belong. We have with these objects to do no longer with a special modification only of our own type of suns, but find ourselves in the presence of objects possessing a distinct and peculiar plan of structure.
In place of an incandescent solid or liquid body transmitting light of all refrangibilities through an atmosphere which intercepts by absorption a certain number of them, such as our sun appears to be, we must probably regard these objects, or at least their photo-surfaces, as enormous masses of luminous gas or vapour. For it is alone from matter in the gaseous state that light consisting of certain definite refrangibilities only, as is the case with the light of these nebulae, is known to be emitted.

D'Arrest
[Siderum Nebulosorum Observationes Havnienses]
[Drawing on p. 334]

Dreyer (1877)
GC 4447, h. 2023 [M 57]. Drawings in D'Arrest, S.N., p. 334, and in Holden, Wash. Obs., 1874, Plate VI, Fig. 2.

Vol. VIII of the Annals of the Observatory of Harvard College, which was received at Birr Castle in the summer 1877, contains lithographs from drawings by Mr. Touvelot of the following Nebulae: GC 116 [M 31] (Pl. 33), 1179 [M 42] (Pl. 24, Woodbury type), 4230 [M 13] and 4294 [M92] (Pl. 25), 4355 [M20] (Pl. 32), 4447 [M57] (Pl. 34), 4532 [M27] (Pl. 35).

Dreyer: NGC 6720.
NGC 6720 = GC 4447 = h 2023; M 57, Darquier.
RA 18h 48m 23s, NPD 57d 8.6' (1860.0) [Right Ascension and North Polar Distance]
!!!, ring, B, pL, cE (in Lyra); = M57
Magnificient, ring shaped, bright, pretty large, considerably extended [elongated] (in Lyra).
Remark: Figures in: P.T. 33 [J.H. 1833], plate ii, fig. 29; P.T. 44 [Lord Rosse 1844], plate xix, fig. 29 (*); d'A [d'Arrest, Instrumentum magnum aequatoreum, Havniae, 1861], plate ii, fig. 5; d'A 2 [d'Arrest, Siderum Nebulosorum Observationes Havnienses, 1867], p. 334; Wash. [Holden and Trouvelot, Washington Observations, 1874, App. I], plate VI, fig. 2; H.C. [Winlock and Trouvelot, Annals of Harvard Observatory, vol. viii], plate 34.

Curtis
[Descriptions of 762 Nebulae and Clusters photographed with the Crossley Reflector. Publ. Lick Obs., No. 13, Part I, p. 9-42]
NGC 6720, RA=18:49.9, Dec=+32:54. [Publ. Lick Obs.] Vol. VIII, Plate 59. M57; the well-known Ring Nebula in Lyra. Planetary. See the sketch included in the paper on Planetary Nebulae [description below]. 5 s.n.

[The Planetary Nebulae. Publ. Lick Obs., No. 13, Part III, p. 55-74]
[with drawing and Lick b/w photo, Fig. 46 and 46a]
NGC 6720; 18h 49.9m; +32d 54'
The Ring Nebula in Lyra. Exposures 1m to 2h. Central star magn. 15.5 visual (Burnham) and about 13 photographically. The outside dimensions are about 83"x59" in p.a. 66deg. The structural details of this well known and remarkably complex object are accentuated in the drawing [Fig. 46]. Rel. Exp. 6.

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