ARTICLE PAGESAPPENDIX NO.I.
|
Components Mag. |
Colour | Position | Distance | Date | Authority |
A 5 B 5 |
- - |
AB 261° 54′ | 6.28 | 1822.69 | σ |
A 4.5 B 4.5 |
Greenish yellow Reddish yellow |
AB 262° 30′ | 6.19 | 1828.71 | Σ |
A 5 A 5 |
Greenish Yellowish |
AB 262° 12′ | 6.11 | 1828.76 | Σ |
A 5 B 5 |
Yellow green Egregiously red. |
AB 261° 12′ | 6.07 | 1829.62 | Σ |
A 5 B 5 |
Yellow Yellow |
AB 261° 06′ | 5.88 | 1832.53 | Σ |
A 5.5 B 6.0 |
Light apple green Cherry red |
AB 261° 48′ (w 9) | 6.1 (w 9) | 1833.78 | Cycle |
A - B - |
Gold yellow Gold yellow |
1844.5 | Sestini | ||
A - B - |
Pale green Reddish |
1851.2 | Hart.Spec. | ||
A - B - |
Greyish white Greyish white |
1856.58 | Guajara | ||
A - B - |
Light green Pink |
AB 261° 11′ | 6.15 | 1857.42 | Fletcher |
A - B - |
Greenish Reddish |
AB 260° 11′ | 6.08 | 1857.42 | Wrottesley |
A 5.7 B 6.0 |
Light apple green Cherry red |
AB 260° 30′(w 7) | 5.6 (w6) | 1857.63 | Spec.Hart. |
A 5.7 B 6.0 |
Yellowish with blue tinge Slightly reddish yellow |
AB 261° 4′(2)(w1) | 6.29(2)(w=0.6) | 1862.72 | Eichies |
Remarks by C. P. Smyth. [*79]
“The magnitudes may vary
through half a magnitude.
“The colours vary
astonishingly; and, as one of the most; remarkable cases in the
heavens, may be treated at length. On my return from Teneriffe I had
communicated the observed colours of this, amongst a series of other
stars, to my father and his friends, and they seized on my equality
of the colours of the two components of 95 Herculis, as one great
anomaly in my list, and chief divergence from the Cycle, where they
are extremely contrasted; and, several observers being called
together the next summer, they proved unanimously that the Cycle was
right. I remained, however, positive that I had observed the alleged
equality, and on two nights; for, being surprised, and in a manner
amazed at it, having promised on the strength of the printed
description to show a bystander a case of remarkably contrasted
coloured to try to perceive some approach to them; but, though
certain strange flickerings of colour appeared on one of the nights,
there was nothing to disturb the general equality of the two discs,
and their close approach to white, or a light neutral grey.
Its real changes of hue.
“All this tinge it is true that Sestini’s observation of 1844 was on record, I, renouncing both the stars gold — yellow, but; it was not until recently referring to Struves original observations, which are partly given above, that I became convinced of this being a pair of cosmical and brilliant changers of colour; A passing
from yellow
to greyish, from that
to yellowish with blue tinge, from that
to greenish, from that
to light green, from that
to light apple green, from that
to “astonishing yellow
green,” and from that
to yellow again.
“in a period of probably twelve years, while B in the same time passes
from yellow
to greyish, from that
to yellowish with reddish tinge, from that
to reddish, from that
to cherry red, from that
to “egregious
red” and from that
to yellow again.
“Real [*80] physical changes, these in each star, there can be no doubt; though in this case the one colour is so generally the complement of the other, a case will be found farther on where one component of a double star goes through brilliant periodic changes of colour, without the other component very sensibly altering its tint? [16]
Is it a binary system ?
“In position and distance ‘fixity’ and an optical character have hitherto been both assigned and confirmed to 95 Herculis; but now, with the assistance of the Elchies observation and the B.A.C-proper motion, which, does not make its appearance relatively between the two components, I have the utmost confidence to declaring the pair to be binary, and undergoing a slow retrograde movement in angle, of about 2° in forty years, roughly — a conclusion which, though it must prove fruitless for ages in enabling the orbit to be approximated to, is nevertheless of vital consequence in studying the strange chromatic problems which the stars present.”
Notice from Bedford.
While the above exposition was being prepared for the press, the changes of hue in 95 as been noticed been entirely independently at Bedford, by Captain John Huggins, who favoured me with the details before he could have possibly heard of the operations at Elchies. His statement is printed in the “Monthly Notices” of the Royal Society for November 1868, from which publication it is here extracted.
Mr. Higgens, in a letter dated Bedford, 17th April 1863, addressed to Admiral Smyth, writes as follows:
“I beg to forward a few
notes on 95 Herculis.
“When I last
saw the star, in the autumn in of last year, the colours were as
noticed in the Cycle; A, apple-green; B cherry red.
“I first saw it this year on the 23rd April,
but the bright hues were not there, and greenish-white and
pinkish-white were all I could affirm.
“May 10th. Hues more faint. I could only record them as dull white, both A and B. [*81]
95 Herculis
“Aug. 1st. A,
greenish-white; B, yellowish: both changing lightly till 95
Herculis. Aug. 12, when they showed as in tile Cycle; A,
apple-green; B, cherry-red. A first shewed signs of deepening
colour, the hues becoming more apparent every night, B changing from
yellow to red more rapidly.
“It was not possible to note night by
night the amount of change; but it was very palpable after an
interval of three or four nights, and continued so till both stars
showed their normal colours.
“The instruments used were, a
3¼-inch achromatic with 80, and a 4-inch with 115; both
glasses by Cooke, of York.”
Admiral Smyth remarks:
“The star in question,
95 Herculis, is now a crucial instance of sidereal colour-changing;
and it has given some little trouble, both to my son Piazzi and
myself already, in poring over the registered observations.
“It is to be hoped that a field of
research at once so elegant, easy, and useful, will be followed up
by some of those Fellows of the Society who possess both means and
leisure to pursue the interesting inquiry.”
“The Astronomer Royal, however,
suggested to Admiral Smyth that the simultaneous change for the two
stars is suspicious, and looks like a possible change in the
telescope.”
Epoch of 1864.
Captain Higgens continued his watch over this object, during the apparition of the present year with commendable perseverance; and 1864 on the 10th of August wrote thus:-
“I beg to forward the
results of thirty-eight observations of 95 Herculis, made on
different days from May 21st to August 8th, with Cooke’s achromatic telescope of 4-inches aperture
and 5-feet focus, under powers 115 and 200.
“Of the thirty-eight observations eight are
noted as simply normal, nineteen as showing A fainter than last year
when in full normal coloured and eleven as showing both A and B
fainter; and my impression is, that they are not so vivid as they
were last September, and that A shows more loss colour than B,
though neither to the extent of justifying their being classed as
anything but normal, though somewhat faintish.
“It hits always struck me that the
definition of their colours in the Cycle, a slight apple-green and
cherry-red, is the most graphical description that could he applied
to these beautiful objects. I have watched then with great care and
interest, from having had the good fortune last year of detecting
the change of colour from white to their normal condition, as
reported to you.”
On the 11th the Captain informed me, “I received a letter from the Rev. Mr. Webb this morning, in which he incidentally mentions 95 Herculis as follows:- ‘I fancied the other night the red decidedly more marked than the green.’ Now, as I had not mentioned to him that I have been engaged in observing 95 Herculis this year, I feel pleased at so independent a confirmation of my notation A (green) being fainter than usual.”
[16] This alludes to the most interesting 70 Ophiuchi, the B of which my son assumes to vary through a variety of colours, at periods yet unascertained; and that yellow, green, violet, purple and red, are permanently registered. But from many conditions of the case, I am persuaded we must await more observations before conclusions can become at all satisfactory.
Last Update : 26th April 2017
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