HISTORY of the JEWEL BOX
PART TWO : C. 1860 to 1872
Investigations by Francis Abbott and H.C. Russell
During the 19th Century, one of the most controversial debates was to surround the cluster Kappa Crucis, originating from the observations and deductions made by Francis Abbott from his private observatory in Tasmania during 1861. This culminated with new micrometrical measures of the cluster made by the New South Wales Government Astronomer, Henry Chamberlain Russell, whose odd results seemed to confirm the questionable view that the Jewel Box stars had apparently moved over several decades. This issue caused significant repercussions for subsequent southern observers.
Francis Abbott (1799-1883) was born in Derby, England, and in his early working life was a watchmaker, first in Derby, and then in Manchester. He married in 1831, having seven children and life seemed to have been progressing normally. However, in 1844, under quite dubious circumstances, he was charged under false pretences for obtaining two watches. Found guilty of the crime, he was then sentenced to seven years as a convict at the penal colony in Hobart, Tasmania, which he arriving in June 1845. Abbott then began his time of incarceration doing hard physical labour for one year, then working as a servant in another. His interest in meteorology started when he became involved with the work being performed at the geophysical Rossbank Observatory in late-1847. This building was erected in 1840 by Governor Franklin, to do southern geomagnetic observations — no doubt because of magnetic variations caused by the aurorae visible from Tasmania — and to do general weather observations. Some three kilometres north of central Hobart, Rossbank now is located within the Botanical Gardens in the suburb of Moonah. Although a convict with some years to serve, Abbott continued to help make the necessary weather observations that remained for the rest of his life. Such duties were definitely better than the average convict, and no doubt his overall demeanor would have fallen in his favour. Abbott was finally released from custody in March 1849.
Upon his release, he soon began another small business in Hobart, and as in making and fixing watches and clocks, then during 1850, his English family joined him in Hobart when offered free passage to Australia. In the decade following, his business became successful, but he continued doing meteorological and astronomical observations. Even his published weather observations were eventually useful in determining local conditions in Hobart and Tasmania.
As a keen reliable amateur astronomer and good observer, he was soon was to gain a better reputation. His meteorological and numerous astronomical observations were to be printed in the “Papers and Proceedings of the Royal Society of Tasmania.” After about 1851, Abbott provided services towards maintaining local time and producing Hobart weather observations. This continued uninterrupted until 1879. His growing reputation was also greatly enhanced by many international astronomical papers and articles, like those in the Astronomical Register and the prestigious Monthly Notices of the Royal Astronomical Society in London. Most of these paper featured details several few bright comets, like the Great Comets C/1861 and C/1865 B1; and also on the astonishing brightness changes and nature of the phenomenal intrinsic variable star, η Carinae, which during this general period reached −0.8 magnitude in 1847 — outshone only by Sirius, the brightest star in the sky. Abbott was unlikely to have observed the initial bright outburst of this star because he was still serving time, but would certainly have known about it. His first recorded observation was during March 1856, when the variable was starting its steady decline, though at this time, η Car was still shining at about first magnitude.
This prestige continued until 1871, when some of Abbott’s published claims were severely criticised by several well-established northern observers, including Sir John Herschel and the Astronomer Royal, George Airy. After this initial public humiliation, his papers became well scrutinised and questioned by these same astronomers, and he was eventually forced by them to both detract his claims and to be ostracised from the publications of the Royal Astronomical Society by its Editor. Although this notoriety was to be terminal to his general standing among the astronomical community, some useful astronomical observations continued. Left to his own devices, his career as an amateur astronomer probably culminated in the publishing between 1878 and 1880 of three books on general astronomy.
For whatever reason, around the early 1860s, Abbot began to believe that the universe was not static and eternal as assumed from the ancient Greeks and the Biblical accounts. He thought it was continuing to evolve and change — yet more importantly, being actually observable within the short timeframe of human history. Some did speculated these views were no doubt due to the observations — both from the dramatic changes of the star η Car or of the variations in structure observed in the bright comet that appeared in 1863. Later he even speculated on the similar changes to the general appearance of the huge-sized nebulosity, the magnificent southern Eta Carinae Nebula or NGC 3372.
In May 1862, he recorded observations of the Jewel Box, which he contended that these stars were showing;
“…certain changes that are apparently taking place in the number, position, and colour of its component stars.”
These dramatic words were published with his observations of the cluster that was entitled “On the Cluster χ Crucis, R.A. 12h 43m 36s, N.P.D. 149° 25′ 31″ (3435, H.) Lac. 1110 (Neb.)” MNRAS, 23, p.32-33 Aug (1862). Here he describes, by carefully comparing Herschel’s and Dunlop’s drawings and descriptions, that many of the stars had changed in relative position, number of stars and colour. Here Abbott goes on to s uggest;
“Some hesitation might be felt in following the author of the Cape Observations, with the means he employed, were it not for the encouraging invitation that is given for other, observers to note any remarkable change that may have taken place since those results were published.”
This obviously suggests that the cluster stars were truly undergoing some evolutionary changes, and hence, if true, made the Jewel Box an important deep-sky object for study. Knowledge of the evolution of stars with the first emergence of astrophysics theory was fairly new in concept, and during this time there were those who firmly believed in the literal Biblical account of the creation. Many had assumed then adopted the postulate made by the Irish Anglican, the Archbishop James Ussher that the Earth was created was created in 23rd October 4004 B.C. If such a result were correct, then when this was applied against the Aristotlian concept of the eternal stars, meant that any changes seen in them were (incorrectly) conclusive scientific proof of the recent formation of the universe by God.
Abbott’s observations were fairly detailed, showing about seventy-five (75) stars using his 10.4cm (4.1-inch) 5-foot f/14.5 refractor. He describes the telescope as;
“The …stars which are given in the drawing, were observed, and their position laid down by means [an] …object-glass of excellent quality. The power used for the purpose of laying down the position of the star was 135 [×]…”
Although the original drawing was never published, it was displayed to a the meeting of the Royal Astronomical Society in November 1862. The comparison of the stars positions, were made by used John Herschel’s original drawing made during his South African expedition of the southern skies in 1835, with of the cluster showing about 70-odd stars. This early drawing was published in the substantial observational tome of ; “Results of Astronomical Observations Made During the Years 1834,5,6,7,8, at the Cape of Good Hope… (1847). Here Abbott describes;
“Having, therefore, no knowledge of any other observation being made, or popular account published of κ Crucis, except that at Feldhausen, I have adopted it for comparison with the observations now made, and given in the drawing, for the present epoch… The same Greek letters [as originally given by John Herschel] have, with one exception, been used in the drawing as those used in the Cape Monograph, but not exactly following those used in the Catalogue. The letters and numbers, when in combination, are grouped together in brackets, and intended to show colour and position only.”
Towards the presumed changes, the major changes occurs with the main bar of three stars, placed in the cross-bar of the “A” asterism, and also along all the axis’s of the main A-shape. Abbott describes these changes as;
“In the Cape Observatory φ; is laid down to the west ι and δ they are now, however, situated in a straight line, which, when continued, reaches the star ζ ; a straight line also drawn through α and β, cut δ ; but the two conspicuous stars in the drawing, ν and θ — is the three small stars marked 12 across the belt, are not shown at all in the Cape Monograph ; there are also two considerable stars, κ and λ, to the far west, which are not seen in the Cape description.”
These views at the time were meet with much scepticism in the wider astronomical community. This was again made worse by Russell’s measures some twenty-years later, seemingly just confirming that these changes were unlikely. Today, it is clear that these changes are impossible considering the distance of the cluster and against the very small proper motions atypical of all open and globular star clusters. These changes in the drawings were more to do with the slight inaccuracies made by John Herschel, and whose slightly different placements where magnified into significant change. The observers were also subliminally influenced by Dunlop’s original drawing which he describes as “accurate”, which was clearly distorted. Human eyesight seems good at inspecting straight lines, and can readily interpret subtle difference in non-linear differences. When given such changes, we can immediately recognised such imperfects, which roughly in the order of tenth of one degree. The other explanation is that both John Herschel and James Dunlop did not pay as much attention to these problems as they had no real drawings as comparison, and likely never thought of it as important to record. Were it so, then this problem might never had arisen in the first place. (A further discussion of H.C. Russell’s interpretation of this is given below.)
Abbott’s Changing of the Star Colours
As for the star colours, Abbott suggested some of the Jewel Box stars have also changed, which he assumed was direct evidence of apparent stellar evolution.
Such views were not new, and Francis Abbott was not the first to state them. This same idea was later adopted by Admiral Smyth in his 1864 book, now known as the Sidereal Chromatics — and especially towards the coloured double star 95 Herculis, which he thought was undergoing such stellar evolution. Overall Abbott’s colour observations were made differently than the star positions, which he says were achieved, using the same 10.4cm (4.1-inch) 5-foot f/14.5 refractor, but using the preferable low-powered 270× comet eyepiece. With this telescope he saw all the general star colours as;
“…where distinct colour could be detected… the smaller stars… from the 10th to the 14th magnitude, are generalised, and all partake of nearly the same colour (Prussian blue), some with a little more or less tint of red or green mixed with the blue.
These colour (and the positional results) were compared on the evening of 24th May, 1862 with another slightly larger telescope described by Abbott as; “…7-foot achromatic by Dollond.” He describes these observations as;
“…it was capital night — no moon, quite calm, and the object near the zenith ; but with such a night I was not, with the means employed, able to bring out stars of the 15th and 16th magnitude given in the Cape Catalogue.”
The two stars, α and β apparently retain their colour ; but γ has changed from greenish white to blueish purple ; δ from green to pale cobalt; ι from red to Indian red ; ζ from green to ultramarine; φ (marked η in the drawing) from blue green to emerald green ; α2, called ruddy, partakes now of much the same colour as all the small stars of that magnitude.
Russell’s Investigation of Possible Motion in NGC 4755
In 1872, in response to Francis Abbott’s suggestion, H.C. Russell carefully measured and catalogued 130 stars, and compared the positions and cluster’s members made in 1834 by John Herschel. This was publishing in the MNRAS, 33, 66 (1873), and was immediately meet with some real biting criticism.
D. 1880 to 1891
The Early Images of NGC 4755
During the photographic surveys Gould listed and positioned 129 stars from two suitable plates of the cluster, among the eighteen-odd plates in all taken. The latter images were both photographed in 1881 that were later privately published by Gould in 1897. Subsequent analysis of the plates gave the plate magnitude limit as around 12 to 12.5 magnitude.
A further description of NGC 4755 and another of the first southern astronomical photographs was by Robert Ellery also appears in MNRAS, 45, 395 (1883). H.C. Russell also achieved similar photographic results in 1890, whose fainter magnitude limit was around 14th. The result and image was presented by Russell to the Royal Society of New South Wales, July 1, 1891. Entitled “Preparations Now Being Made in Sydney Observatory for the Photographic Chart of the Heavens” (1891), it showed the usefulness of the application of astrophotography for celestial objects in the southern hemisphere. (A full version of this article also appeared in the ASNSWI “Universe”, April (1984)). Appearing as Plate XI in the original. I have reproduced a scanned version as Figure A.
Figure 10. Henry Chamberlain
Russell’s Image of the