PB 151380

jBoulder laboratories

^0.21

VARIATIONS OF GAMMA CASSIOPEIAE

BY S. R. POTTASCH

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
National Bureau of Standards

SEP 2 1 1960

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21

August 1959

VARIATIONS OF GAMMA CASSIOPEIAE

S. R. Pottasch

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VARIATIONS OF GAMMA CASSIOPEIAE

by

Stuart R. Pottasch

National Bureau of Standards

Boulder, Colorado

ABSTRACT

The variations of Gamma Cassiopeiae between

I89O and 1950 are summarized and discussed. The

variations of visual magnitude, color temperature,

radius and electron density of the shell, and the

spectral variations are depicted.

I. INTRODUCTION

A. Gamma Cassiopeiae belongs to a class of stars commonly

referred to as B emission stars . It is an irregular variable,

whose visual magnitude varies not more than 1 magnitude on either

side of its mean +2.25. Its 1900 position is: R.A.O^CP.T,

Dec. +60°ll f

. The Henry Draper Catalog (HD 539+) gives it a visual

magnitude of 2.25, & photographic magnitude of 2.01 and a spectral

class of BOp.

Gamma Cassiopeiae has been assigned by the Yale catalog a

trigonometric parallax of +0" .03^±11 which corresponds to a distance

of 31*15 parsecs. This leads to an absolute magnitude of -0.5 which

is sub-luminous for a BO star. Caution is always advised in the use

of trigonometric parallaxes under +0" .050, so that no definite con- clusion may be drawn. Application of the criterion suggested by

Petrie to determine the absolute magnitude from the equivalent width

of H> has been applied, and an absolute magnitude of -5»0 derived,

corresponding to a parallax of +0" .0031 and a distance of 320 parsecs. The star has a proper motion: \xa = +O".026, |i5 = -0" .002,

and has an 11th magnitude companion 2" from it which shows common

proper motion.

B. The observations, which it is the purpose of this paper to

compile and discuss, are of three types:

1. Spectra and spectral data

2. Visual and photographic magnitudes

3. Color temperatures, gradients, and colorphotometry.

The observations have been taken by many people with different instruments. In the present compilation when the same data

were available for smal ler time intervals than 3 months, only 3 month

averages were used. There are two reasons for this:

1. Observations are not consistently available for

such small time intervals.

2. The unaveraged data show marked irregularities

sometimes over a period of hours or days. Most of this is due to

instrumental and measuring inaccuracies, but some seems to be real.

However, considering these variations to be real, absolutely no pattern was discernible.

It was thereforethought advisable to first try to understand the

larger scale time variations and to wait for the data to become

available to study the small time scale variations.
II. THE VARIABILITY OF 7 CASSIOPEIAE

A. I83O - 1928

1. Edwards (l^kk) studied the records of the magnitude of

7 Cas. which were available at various periods from I83O - 19^2. He

supplemented this with radial velocity from the period 1911 - 191^

and some spectroscopic data from the period 192*1- - 1932. He came to

the conclusion that "a periodicity is suggested for these changes,

consisting of two maxima, separated by ^.30 years, in a main period

of IO.67 years".

His work can be criticized on the following grounds:

Considering only the period before 1928:

a) He does not have a consistent series of measures

of any one quantity covering even two of his periods.

b) The variations that he based much of his argument

on are in most cases at or below the probable errors which should be

assigned to the quantities in question.

c) Many of his supposed maxima are found, as for

example in his discussion of the radial velocity measures over a three year period, by extrapolating a curve, thru which a straight

line might easily satisfy the data to the accuracy inherent In the

measurements, to maxima on either side of the data. The maxima are

then separated by almost seven years.

On the basis of the present data, it seems that no large

scale periodic variability was present during the period before 1928.

The question of small scale variability, at the edge of instrumental

accuracy, is an open one.

2. Lockyer (1933 a,b, 1935 a,b, 1936) made a study of the

variability of 7 Cassiopeiae from plates taken at Sidmouth from the

period 1892 - I895 and again from 1921 to 193^. He states that as far as he can detect, the magnitude of the star remained constant

before 1932. He looked for variability in the structure of the

emission lines of hydrogen. The lines are seen as wide emission

lines with a central absorption. This absorption may shift its

position within the emission line causing the ratio of the violet part

of the emission line to the red part of the emission, to vary. This

will be referred to as V/R variability. Lockyer, from his measures of

this quantity for H7 and H5 said he was able to detect variability

between 1921 and 1928, within a period of about h years. His conclusion
for this period is open to question on the following grounds:

a) Only 13 spectra were available in this 7 year

period.

h) He measured H7 both by eye and with a calibrated

wedge. The difference between these measures for any single spectrum

is about equal to the amount of the variability. Clearly, since the

variability that he detects is so close to the observational error,

the question cannot be said to have been settled. A period certainly

cannot be said to have been determined.

3. Cleminshaw (1936) using l6o spectrograms obtained during

an interval of 21 years (191^- - 1935) states that "observations made

from 1914 through 1928, like those made by R. H. Curtiss (1916) from

1911 to 191^j do not show any undoubted variation in radial velocity

or in the emission ratio V/R.

The conclusion is that the velocity and emission ratio

remained constant from 1911 through 1928, except for possible shortperiod variations of small amplitude.

B. Spectra I895 - 192^.

Considering that the most minor changes only occurred

in 7 Cas. in the period before 1928, it is felt warranted to compile

a composite spectrum for the star in this period. This composite

spectrum is based chiefly on the work of R. H. Curtiss, and secondarily

on the work of Sidgreaves (1899), Miss Maury (1897), Baxandall ( 191*0

and Miss Heger (1922) . The composite spectrum is shown in Table I.

There are individual differences between the spectra which

might indicate some degree of variability. But the measures are not

complete enough for a definite statement to be made. For example,

Sidgreaves sees a good deal more Nil than any other observer, while

Curtiss sees SII. Miss Heger, looking in the red, see a great deal

of Fell, and Fell was probably stronger when she observed it than for

the other observers. The identifications given in Table 1 are my own.

The radial velocity as derived from the absorption lines

remains constant at about -6.8±^.0 Km/ sec. during this interval.

1929 - 1935.

After I928, systematic changes begin to be observed in the

spectrum. Cleminshaw (1936) and Lockyer (1935a) observed an increase

and then a drop in the emission ratio V/R (Figure 8) . The spectrum
was observed by Struve and Swings (1932) in about 1931 and- seems to

have changed a little in the following way: the singly ionized metals

appear to be stronger in emission, possibly [Fell ] appears, CrII

appears for the first time, and the hydrogen lines appear stronger

in emission. The Hel lines are still the most prominent part of the

absorption spectrum and Hell still appears to be present, as does Oily

Nil, Silll, SilV, in absorption.

The main features of the data derived from spectral observation are plotted. Figure 1 shows the radial velocity, Figure 3

the width of the hydrogen lines in kilometers/ sec, while the

temperature variations, of which more will be said later, are shown

in Figure 6

In 1932 there was a marked change of the V/R ratio. The

violet emission component became much stronger than the red, and the

radial velocities, which had been small and negative, were observed

by Cleminshaw (8) to become small and positive. The Fell lines

underwent simi lar changes to the hydrogen lines. The temperature

of the star began to decrease while the width of the hydrogen lines

showed an increase.

In 193^ a new cycle of changes began. Heard (1938) and

Cleminshaw (1936) observed the separation of the two emission com- ponents of the H and Fell lines to decrease, the lines becoming

single in May 193^* Cleminshaw assumed the strong violet and weak

red components approached until unresolved, blended, became equal

in intensity, reversed inequality, and then separated again. This is

in agreement with typical Be variables in which the separation of the

two emission components is least when they are equal in intensity.

The width of the H decreased while the temperature shows an increase.

By November 193^ the central absorption lines of H were

distinct again, now with the red emission components stronger than

the violet. The red component reached maximum strength in March

1935* after which McLaughlin (1936) observed the violet components

to increase in strength until equality wa s reached in May 193& •

Heard (1938) observed that several plates taken in 193^ showed

Hel kh"Jl in emission as well as absorption. This had not been observed

before, the Hel always had appeared as simple, broad, hazy absorption

lines. He also noted the presence of Hel 3889, indicated by the

enhancement of H8.

The Balmer series could be traced in emission to H 20 at this

time. V/R variations for Fell and Hel were also measured and found

similar but smaller than those for H.
Beginning in August 1935* a very sharp absorption due to

Hel 3889 "began to appear. It was followed "by the appearance of other

sharp Hel absorption lines. The strongest: X3965, \k026, \hkjl were

as sharp, although not as strong as \3889.

Simultaneously with the appearance of these sharp Hel lines,

an increase in the strength of the H central absorption was observed.

Measures of the blend H8 and Hel showed that after September 1935 this

strong line was due almost entirely to Hel. Fell generally behaves

similarly to H and Hel.

1936 - 1939-

A detailed description of this period is given by Baldwin

(1938, 1939 a, b) from a series of 70 spectrograms obtained between

March 1935 and October 1938.

Table II is a summary of the spectrum of 7 Cassiopeiae,

primarily for 1937 although the spectrum was very similar for the

few years preceding it. The ^wavelengths were taken from Baldwin

(1938), Belorizky (1952), Cherrington (1938), all of whom cover the

period of the middle of 1937> with reference to the work of Heard

(1935) and Struve and Swings (1932) . The intensities up to HB are

adopted from Baldwin, while from Hp to Ha, W,M, S, SS, SSS are used to

indicate an increasing intensity. The identifications are, as in

Table I, the responsibility of the present writer. The spectrum is

entirely one of emission. An underlying broad absorption of about

600 Km/sec. width is seen continuously over the entire period but no

identification or wavelengths are available. Presumably this broad

absorption never changes and is the same as that seen clearly in the

1950 f s (to be described).

After June 193^, a sudden decrease of strength of the sharp

absorption lines of H and Hel was noted. At the end of this decrease,

all the Hel lines, except 3889, appeared as widely separated emission

pairs with no sharp absorptions between, while Hel 3889 was present

in absorption until the end of February 1937 . After this fading of

the absorption lines, or possibly beginning coincidently with this

fading, there occurred a steady increase $f the emission intensity in

all the lines, and the two emission components were observed to

approach each other. This narrowing recalls the occurrence of this

phenomenon in 193^ • The emission edges of the broad shallow absorption

lines of Hel began to sharpen and approach each other, remaining,

however, equal in intensity during the entire period (through I938)

except D3(5876). The violet components of the H lines steadily

strengthened as the two components approached each other. The Fell

lines, which were formerly observed to be merely diffuse patches of

emission, so that only a few lines were measurable, sharpened and

strengthened, as did the Sill and Mgll emission components, until p-IT

the emission pairs blended to single lines in 1937

.

5
The narrowing of the emission lines coincides with the

large rise in visual magnitude. The single line stage coincides

exactly with maximum light. Minimum temperature also occurs at

this time.

By the end of November 1937> "the lines had widened and were

just resolvable as double emission lines, with the red component

equal to, or slightly stronger than the violet. By the end of December,

the H lines were clearly separated, with the violet component strong

but rapidly decreasing in strength. The Hel and Fell lines had

widened and weakened but did not clearly separate until later.

Then a new and unexpected feature was observed in the lines

of all of the elements studied. In April 1938> the lines suddenly

became fuzzy and almost immeasurable, and examination disclosed that a second pair of emission lines, too close to be fully resolved, had

appeared in the position previously occupied by the central absorption

line. These faded by August 193°^ and the old pair strengthened again.

During 1938* the spectrum was again characterized by absorption

lines, which were not as strong, however, as those in 1936. H and Hel

appeared more strongly than the other elements. This stage seems to be

followed by another emission line phase, but it is neither long nor well

marked.

Then, in the autumn of 1939j "the sharp absorption lines reappeared in greater strength and numbers than ever before.

I9J4O - 195^.

Table III shows the observed spectrum at the beginning of

l^kOf as before, in the region between H9 and Ha. Spectra are available

down to 3100A during this period, mainly due to Baldwin (19^1) and Struve

and Elvey (19^0) . H and Hel are the strongest features of the shell

absorption spectrum, with lines of Felll appearing in large numbers,

particularly In the ultraviolet. It cannot be said that any other element

or stage of ionization is definitely seen at this point (December - January, 1939 - 19^40) . There are a large number of unidentified lines

which Baldwin has suggested might be due to Tilll, Nilll, and CrIII and

perhaps other doubly ionized metals; their spectra, however, are practically unknown. It should be mentioned that all of the Felll

lines observed arise from a metastable level. No others are con- spicuously observed.
Changes in the spectrum occur rapidly. In March 19^-0,

Swings and Struve, observing in the visible region found that the

sharp absorptions were weaker, and the underlying broad absorption

lines which had been veiled, became much more conspicuous . They

also note the presence of Silll, half in absorption, half in emission.

The last part of 19^0 and 19^1 was characterized by the further

conspicuousness of the broad absorption although many sharper lines

are still seen. Felll is still present and familiar lines of Oil,

Nil, CII, CHI, Silll and SilV are beginning to be observed. MgH

is present in absorption. Detailed descriptions of the spectrum at

this period may be found from Peachey (19^2, 19kh) , Hase ( 19^40 ) and

Tcheng Mao-Lin (19^1)

.

Detailed observations on high dispersion equipment are not

available during the next seven years. Morgan observed the spectrum

toward the end of 19^-1 and classified it as BOIV peculiar. The blend

at 4650 (CHI, Oil) was prominent and little or no emission was seen. The star was again observed in October I9M4 by Belorizky (19^-5) who

found the "broad absorption lines of H and Hel, but found no emission

at all. The emission reappeared again in September 19^-6 (Belorizky and

Fehrehbach, 19^7) an(i is seen continuously toward the red end of the

spectrum from then until the present. Table IV shows the observations

of 1946.

The variations in the spectrum during the whole period seem

to be of a minor variety. The spectrum was again observed in 19^-9 ^J

the Burbidge's and Wang (1952) . At this period Ha, Hel 5876 and H£

were seen in emission, and the remainder of the lines were broad

shallow absorptions, which included H, Hel, OH, Silll, SilV, Nil, CII

and SHI, a spectrum very reminiscent of the broad shallow absorption

lines observed by Curtiss in 191^. The radial velocity was determined

for this period and a continuous record for the period of one month was

obtained for the equivalent widths of several H, Hel and Oil lines. The

variations were periodic and amounted to ±2 Km/sec. but their reality

may be doubted.

The period between 19*4-7 and 195^ is summarized in Table V;

most of the information is due to Kcpilov and his co-workers (1954,

a,b, c). They attempt a characterization of the profile of the lines,

although with their equipment this is a difficult task. The quantities

given in Table V are: WX is the equivalent width, v is the total width

of the absorption line in Km/sec, r is the intensity at the center of

the line divided by the intensity of the continuum at that point, and

A\ is the half width of the line in angstrom units.
The H lines appear to be wider than the others, probably due

to Stark broadening. The average width of the Hel lines is 663 Km/sed,

while that of the other lines is 66l Km/sec. The velocity of rotation

of some layer at which most of the elements can be said to originate

(an effective photosphere) is 331 Km/sec.

Kopilov also indicates that he feels that superimposed on the

broad shallow absorption line is a weak, but much sharper absorption,

at least in the case of the hydrogen lines. He finds this absorption

to have a whole width of 170 Km/sec. Thus it would arise in a shell or ring surrounding the star at distance of four radii from the star.

During 1950 the star brightened by about 0.5 magnitude and

then fell again. No spectra were taken during this occurrence, however.

C. References of further spectral work done on Gamma Cassiopeiae:

Koelbloed and Walraven (19*40) took several spectrograms of the star in

1939 while the emission was present but declining and measured the

equivalent widths of the emission and absorptions lines observed.

Roach and Blitzer (19^0 ) measured the equivalent widths of the Hel

lines, probably late in 1939> but no date is given. Merrill and Wilson

(19^1) have also measured equivalent widths of several lines at and

around November 19*4-0 • A study of the profiles of the H5 lines is given

from about I93O to May I9IK) by Baldwin (l9^l) and from Jan. I9I+O to

Jan. 19^1 by Swings and Struve (19^1) who also give the profiles for

several other lines (Oil, SilV") during the same period.

Radial velocities during this period are given by Smith and

Struve (1950).

III. DERIVATIONS FROM SPECTRAL MEASUREMENTS

A. The Rotation of the Star.

Curtiss has shown that the width of the emission lines varies

directly as the wavelength. Kopilov has shown that this is true of the

absorption lines too, and that they may be characterized as "broad,

shallow, dish-shaped." Struve (1930) has shown, from data which included

a study of spectroscopic binaries, that these characteristics arise from

the rotation of the star. Assuming the conservation of angular momentum

in the atmosphere of the star, r v = constant.

A parameter Ro is used to indicate the effective photospheric

radius for all the lines between "52 and '5*1-. The great bulk of the star

lies within this radius at any period and it appears to be a more or less

non-varying radius for the production of the broad absorption lines.

8
Figure 4 is a plot of the effective radius for the production

of emission lines at any given date. Before 1930 it remained constant

at about 2 Ro. It varied greatly after this date., a maximum of about

3 Ro was reached at the end of 1934 and an effective photo spheric

radius of about 10 Ro was reached in the summer of 1937° After 1940

the emission lines weaken and disappear.

B. The Balmer Decrement.

Measurements are available of the equivalent width of the

Balmer lines in emission, by Karpov (1932) and for Nov. 1937 by Wellman

(l95l)« These are shown in Table VI. Column A gives the equivalent

width in A times the height of the continuum. Column B gives a multiplying factor to reduce these values to a uniform intensity scale. A

black body distribution was assumed at T = 15*000 K. An error is introduced with this assumption because the continuum cannot be represented

by a black body, but the factor will not be relatively very sensitive.

Column C then gives the relative intensities in arbitrary units.

TABLE VI

A B C

LINE EQUIVALENT WIDTH 15,000°K EMISSION IN BALMER

MULT. FACT. LINE ARB. UNITS

1932 1937 1932 1937

Ha kf.kl 114.- o.4i 26.7 26.7

HP 7-31 17-5 1. 10.0 10.0

Ey 2.70 6.85 1.36 5.02 5.2

HS 1.48 3.36 1.58 3-24 2.9

He O.76 2.06 1.71 1.78 1.9

C. The Radial Velocity and the V/R Emission Ratio.

Figure 1 is a plot of the radial velocity as determined by

the absorption lines of HS and H>. Each point shown is the average

of many taken over a three month interval and the error is probably

not greater than ±3 Km/ sec. for the average. All peaks are of undoubted

reality. The dotted line is the average of all readings before I928,

with great weight being given to the work of Curtiss (1914) and is

presumed to be the radial velocity of the star (-7.0 Km/sec).
The V/R ratio has been discussed before. It can be very

accurately determined. It does not extend past 19^0 because emission

generally does not exist past this date. The general presumption has

been that in a case like this, the V/R ratio is caused by a fixed

emission surface, surrounded by an absorbing shell; the motion of this

absorbing shell back and forth produces an absorption line which moves

across the emission line producing the V/R ratio. From the data, this

could be true for the 193*1- V/R peak. After that, the absorption

velocity by itself (on top of a fixed emission) could not have produced the observed V/R ratio. Qualitatively it can be stated that

during 1935 "the emission photosphere contracted with the absorption

shell fixed, then, in 1936 the emission photosphere expanded as did

the absorption shell. In 1938 the emission continued to expand, with

the absorption shell slowing but not halting until 19^0, after which

time some of it is drawn back to the star but the greater part, in

expanding, lost direct spectral connection with the star.

This discussion is rendered difficult by the fact that the

observed radii (Figure k) are only indirectly formed by the observed

expansion or contraction. The point in the atmosphere at which the

optical depth = 1 may have far greater velocities of both expansion

and contraction than the actual velocity of the material in the

atmosphere of the star.

D. The Number of Hydrogen Lines Observed and the Electron

Density Derived from this.

Figure 5 is a plot of the electron density derived from the

Inglis-Teller formula from the number of H lines observed. The last

observable H line is indicated next to each point.

An order of magnitude estimate of the mass in the outer

layers of y Cas. may be made from the electron density. Assuming

the absolute magnitude is -5*0 for that part of the star associated

with the spectrum showing the wide absorption lines, and assuming

the spectrum is BO, corresponding to a temperature of 25,000°K,

then R is 15 solar radii. The total mass above the photosphere is

then of the order of 10^9 grams and the mass associated with the shell

that caused the absorption spectrum of 19^0 is 5 x 10^7 grams.

It is seen that the distinction that has been used for con- venience in description, that between emission photosphere and

absorption shell, is in reality meaningless. These parts of the star

are probably close together in space as indicated by the density of

the absorption shell after 1939* This was previously indicated by

the closely associated movement of the two levels. It is even probable

that the same atom may take part In both phenomena at different times

and still remain reasonably fixed in space.

10
IV. THE VISUAL MAGNITUDE

The problem of determining the magnitudes of this star with

the existing data is a difficult one and if accuracy of 0.1 magnitudes

is desired, an insoluble one. Observations of this star prolonged

over a period of a year or two by professional astronomers are rare.

The most valuable contribution to this end are the photoelectric magnitudes of Huffer (1939) from Nov. I936 to Nov. 1938.

Edwards (19^-2) has determined both the visual and photographic magnitudes for the period July 19^0 to March 19^-2. Other observations

considered include those of Rigollet (193^) who gives measures on

widely spaced dates from I928 to 1936, cLe Vaucouleurs (19^7) an(i some further measures by Rigollet (19^-3 a,b) .

Among the amateurs, the period between 1937 an(3- the present

has been covered. P. Moore has observed the star over that period and

the AAVSO has on the average 10 observations per month of this star.

These observations are consistent with Buffers work and that of

Rigollet and de Vaucouleurs but do not agree well with Edwards work.

Figure 2, a plot of the visual magnitude from I928 to the

present, is probably better determined before 19^-0. All irregularitie s of the order of magnitude of the probable error have been smoothed.

All bumps are undoubtedly real.

V. THE COLOR TEMPERATURES

The majority of the measures of color temperature were

taken as relative gradients in the system of Greenwich (Greaves and

Martin I938, Vanderkerkhove 1937, 1939, 1952, Hunter and Martin 1939,

Edwards 19^3, Hiltner 19^1, Barber 19^-0, 1950) . In most cases the

two wavelengths used were X^250 and \58OO, although the latter wavelength varied from A.5100 to \67OO, and even \7iOO. The gradients

varied with wavelength used, and an attempt has been made to reduce

the temperatures to a common system, which is described by Greaves

and Martin (1938) • The measures are shown in Figure 6a. Included

are determinations by Hiltner (19^1) who used an absolute gradient

and 11 wavelengths between X^50 and \636O. His results indicate a large scale temperature variation in a period of eight weeks at the

end of 19^0. It is not substantiated by Barber (19^-6), observing at

the same tine, and is smoothed out in the three month averages plotted.

Figure 6b is a plot of the absolute gradients of Barbier and

Chalonge, as reported by Barbier (19^-8) . Not as many measures are available as in Figure 6a. cp^ is the temperature measured at X^-250,

cp2 is measured at A.3500. Measures of the Balmer discontinuity D,

(Figure 7) are also available and serve to point up the strength of

the Balmer emission.

11
ACKNOWIiEDGEMENT

This work was -undertaken at the suggestion and

with the advice of Professor C. P. Gaposchkin. The

author is also indebted to Dr. A. Underhill for reading and commenting on the paper.

12
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"

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Hunter, A. and Martin, E. 1939, Obs. 62, 237.

Karpov, B. G. 1932, Lick Obs. Bull. 457.

Koelbloed, D. and Walraven,' Th. 1940, B.A.N. 3l4.

Kopilov, 1954, Crimean Ap.J. 12, 162.

Kopilov, and Boyachouk, 1954, Crimean Ap.J. 15, 190.

Lockyer, W. J. S. 1933, M. N. 93, 362.

1933b, M. N. 93, 619.

" 1935a, M. N. 95, 520.

" 1935b, M. N. 96, 1.

" I936, M. N. 96, 679.

Lunel, M. 1954, Ann. d'Ast. 17, 153.

Maury, I897, Harvard Annals 28, 100.

McLaughlin, D. B. I936, Ap. J. 84, 235.

Merrill, P. W. and Wilson, 0. C. 194l, P.A.S.P. 53, 125

.

Mustel, Galkin, and Kopilov, 1954, Crimean Ap.J. 11, 59.

Peachey, E. M. 1942, M. N. 102, l66.

1944, U. of London, Type. Circular No. 1.

Rigollet, R. 193, L'Astronomie 50, 572.

11 1943a, Ast. Nach. 273, 272.

" 1943b, Ast. Nach. 274, 35.

Roach, F. E. and Blitzer, L. 1940, Ap.J. 92, 50.

Sidgreaves, 1899, M. N. 59, 508.

Smith, B. and Struve, 0. 1950, Ap.J. 112, 192.

13
Stebbins, J. and Whitford, 19^3> Ap.J. 98, 20.

" " 19^5* Ap.J. 102, 318.

Struve, 0. 1930, Ap.J. 72, 1.

Strove, 0. and Elvey, C. T. 19^0, P.A.S.P. 52, 1^0

Struve, 0. and Swings, P. 1932, Ap.J. 75, l6l.

Swings, P. and Struve, 0. 19^0, Ap.J. 91, 589.

" " 19^1, Ap.J. 9^, 301.

Tcheng, Mao-Lin 19^1, Ann. d'Ast. k, 118.

Vanderkerkhove, E. 1937, Obs. 60, 329.

" 1939, 0"bs. 62, 76.

de Vaucouleurs, 19^7, Ann. d'Ast. 10, 107.

Wellmann, P. 1951, Zs. f. Ast. 30, 99.

14
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16
TABLE II

EMISSION SPECTRUM 1937

Wavelength Intensity Identification Wavelength Intensity Identification

3835.35 18 . H9 4515.42 4.5 Fell (37)

38l4-9.i4-6 0-7 Nill (11)

Sill (1)

4520.18 4. Fell (37)

3853.70 1.5 4522.81 4. Fell (38

3856.OO 6.5 Sill (l)

Sill (1)

4534.25 1. Fell (37

3862.60 5- 4541.62 1-5 Fell (38

3888.76 25. Hel and H8 4549.48 7. Fell (38

3930-34 1. 4555.91 4.5 Fell (37

3933.68 1-5 Call (l) 4558.66 1-5 CrII (44j

3938. M 1. Fell (3) 4576.3 2. Fell (38]1 3964. 7^ 5- Hel (5) 4583.78 9-5 Fell (38]1 3968.58 1. Call (l) 4588.01 0.7 CrII (44j

3970.09 20. He 4618.32 0.7 CrII (44

4009.34 1. Hel (55) 4629.45 5. Fell (37

Fell (37) I4026.26 8. Hel (18) 4666.79 0-7

I4067.09 2. Nill (ll) 4713.30 3.5 Hel (12)

4101.68 25. H5 4731.71 1-5 Fell (43)

4120.82 2.5 Hel (16) 486l . 39 25. Hp

4122.79 1.5 Fell (28)

Sill (3)

4923.94 0.7 Fell (42)

4128.22 3.5 5015 S Hel

4130.88 3-5 Sill (3

Hel (53)

5018 .

5

s Fell (42)

4143.79 3. 5040 M Sill

4173-42 5. Fell (27) 5060 S Sill

4178.88 6.5 Fell (28) 5168.9 s Fell (42)

4233.16 9.5 Fell (27) ' Sell (7)

5197.8 s Fell (49)

4246.0 2. 5234.8 s Fell (49)

4258.15 1. Fell (28) Fell (49)

Fell (27)

5275.8 s 4273.25 1. 5284.2 M

4281.2 2. 5316.4 S Fell (49)

4296.5 3.5 Fell (28) 5326.2 W

4303.18 5-5 Fell (27)

Fell (32) and

5362.5 S Fell (48)

4314.18 0.7 5534.8 s Fell (55)

Sell (14) ? 5875.6 ss Hel (ll)

4340. 4o 40. Hr 5979 M

4351.76 7. Fell (27) 1 6148.9 M Fell (74)

4369.29 0.7 Fell (28)

Sell (14) 1 6238.6 w Fell (74)4374.0 1. 6248.4 M Fell (74)

4385.22 3-5 Fell (27) 6318.3 S Sell 1 4387.96 3- Hel (51) 6347.3 S Sill (2)

4416.77 3.5 Fell (27) 6371.0 M Sill (2)

4471.53 18. Hel (l4)

Mgll (4)

6384.2 S Fell

4481.23 12. 6417.4 M Fell (74)

4489.13 2.5 Fell (37) 6432.7 W Fell (4o)

4491.54 3. Fell (37) 6443.9 M Fell

4508.28 5- Fell (38) 6455.9 S Fell (74)

6492 M Fell

6516.2 W Fell (40)

17 6562.7 SSS Ha
TABLE III

ABSORPTION LIKE SPECTRUM

1939 - 19^0

Wavelength Intensity Identification Wavelength Intensity Identification

3835. hi 18 H9 4101.72 19 H5

3837-88 2 Hel(6l) 4120.84 5 Hel(l6)

3845.62 2 4125.01

3849.47 Nill(ll) 4127.07

3859 A7 4l4l.4l Felll ? 3867.47 3 Hel(20) 4143.78 7 Hel(53)

3868.91 1 4155.87 1 Felll ? 3870.16 1 4168.39 Hel (52)

3871.84 3 Hel(60) 4172.36

3878.20 1 Hel(59) 4186.62 Felll

3888.80 25 Hel and H8 4222.45 Felll

3901.72 2 4225.55 Felll

390^,68 1 4229.76

391^-03 4240.78 Felll

3926 . 60 5 Hel(58) 4244.39 1 Felll

3927.73 2 4248.41 1 Felll ? 3928.84 1 4256.02 1

3929-68 2 4266.24 2 Felll

3931.16 3 4269.37 1

3932.48 2 427^A8 1

3933.65 3 Call(l)

Hel(57)

43^.57 18 Ey

3935.86 1 4352.45 3 FeIIl(4)

3939-79 4366.18 1 FeIIl(4)

395^- h2 1 FeIIl(l20) 4372.03 2 FeIIl(4)

3960 .08 4380.76

3964.71 12 Hel(5) 4382.27 FeIIl(4)

3968.48 1 FeIIl(l20 and 4388.03 9 Hel(5l)

Call(l) 4391.5^ FeIIl(42)

3970.08 19 He ^395-91 2 FeIIl(4)

3997-39 ^397-70 1

4000.76 Felll ^399-95 1

4004.98 2 Felll 4402.05

4009.52 5 Hel(55) 4408.09

4023.90 2 Hel(54)

Hel(18)

4412.13 1

4026.21 13 4415.72 1

4047.44 4419.58 4 FeIIl(4)

4052.14 4427.46 2 NII(56)

4054.29 4430.96 3 FeIIl(4)

4055.38 4434.79 1

4066.92 1 Nill(ll) 4437.87 2 Hel(50)

4070.15 1 Felll ? 4456.52

4071.66 Nill(ll) 4471.65 15 Hel(l4)

4078.92 2 4476.80 1

4080.85 4460.19

4092 . 61 Felll

18
Table III (Cont.)

Wavelength Intensity Identification

4490 . 50 1

4502. 96

lf509.70 1

1+515-55 2

1+520.80

1+5^0.70

1+555-27 1

1+567.60

1+697.27 3

1+713.27 7 Hel(l2)

I+751.80 3

1+861.36 12 HP

4879-75

4899.17 3

I+906.I+O 1

I+921 . 70 5 Hel(48)

5015.1+7 4 Hel(4)

501+8. 21 2 Hel(47)

5063.73 FeIIl(5)

5073-50 FeIIl(5)

5086.80 FeIIl(5)

5126.16 2 FeIIl(5)

5156.81 1 FeIIl(5)

5193.82 FeIIl(5)

5198.02 1

5213.19 1

5219.90

5326.38

5332.31 1

53^5.27 2

5376.22 Felll

5434.ll 1

5444.1+0 Felll(llO) ? 555L71 2

5652.96 1

5777-66

5846.56

5876.47 5 Hel(ll)

5932.47 NII(28)

5942.34 Nil(28)

5993.31 1

6026.98 1

6l4o.o4

6152.10

6207.67 2

6226.45

6410.65 2

6514.97 2

6562.49 Ha

19
TABLE IV

GAMMA CASSIOPEIAE

SPECTRUM 1946

X EM ABS Identification

3934 X Hel(57)+Call(l)

3964 X Hel(5)

3970 X He

4009 X Hel( 55)

HeI(l8J

NII(39)

4026 X

^4-0^4-3 X

4070 X 011(10)

i^089 X SUV

4-101 X H5

4118 X SilV + 011(20)

4131 X SiH(3)

4l44 X Hel(53)

4301 X Fell (27)

4318 X 011(2)

4388 X Hel (58)

4415 X 011(5)

4471 X Hel(l4)

i+64o X 011m

4649 X OIl(l) + CIIl(l)

4840 X

4861 X X HP

4932 X Hel(48)

4935 X

5015 X Hel

5057 X Sill(5)

5875 X Hel

6370 X Sill(2)

6562 X Ha

4340 X Ky

20
TABLE V

SPECTRUM

19^7 - 195^

Width Width

Wavelength WX v km/sec r Z^s. Identification

3771 ab O.63 850 0.88 5.2 ELI

3798 ab 1.03 9I+O 0.81* 5-9 SiIIl(5) and H10

3807 ab SiIIl(5)

3820 ab 0-53 560 0.88 1*.2 Hel

3835 ab 1.16 1150 O.83 6.3 H9

3882 ab 011(2)

3889 ab 1.1*1 1310 0.81* 5-9 H8 and Hel

3912 ab 011(17)

3919 ab CII(1*) and 011(17)

3927 ab 0.31+ 58O O.92 5.0 Hel (58)

3970 ab 1.70 11*80 O.78 5.7 He

3983 ab 011(6)

3995 ab NIl(l2)

1*009 ab 0.3^ 610 0.92 1*.6 Hel (55)

*K)26 ab 59 650 0.88 h.9 Hel (l8)

1*067 ab 0.1*5 730 0.93 6.9 CIIl(l6)

1*070-1*072 ab O.58 790 91 7.5 011(10)

1*076 ab OII(IO)

lf0l*l- kokk ab Nil (39)

1*089 ab O.5I* 670 91 6.5 SilV

1*101 ab 1.98 I65O 0.81* 11.6 H5

1*118 ab O.56 680 O.92 6.6 SilV and 011(20)

1*11*1* ab 0.1*5 670 O.92 6-5 Hel(53)

J+153 ab O.56 580 O.89 l*. 7 0Il(l9) and SII

1*185 ab 011(36) and CIII ?

1*251* ab SIII

1*267 ab CII(6)

1*285 ab SIII

1*318 ab 0.31 011(2)

1*31*0 ab 2.32 1900 0.93 20. H7

1+367 ab 011(2)

1*388 ab O.51 720 O.92 7.1 Hel (51)

1*1+16 ab O.38 630 0.93 6.3 011(5)

1*1*71 ab 0.79 850 O.89 7.8 Helfll*)

1*61*0 ab 0.5!* 555 O.90 5-3 011(1)

1*61*9 ab O.85 650 0.88 6.5 CIII(1) and OIl(l)

1*861 ab & em 1.1*6 650 1.32 6.8 HP

5876 em 1.1*8 810 1.2 11.7 Hel

6563 em.13.9 1180 2.1* 9.4 Ha

21

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JUNE SOLSTICE

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I I I I

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APPROXIMATE LUNAR AGE

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U.S. DEPARTMENT OF COMMERCE

Frederick H. Mueller, Secretary NATIONAL BUREAU OF STANDARDS

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