Intensity variations of H alpha and N II 6 583 A lines in night sky spectru

Dufay, J.

Dufay, M.

Huu-Doan, N.

English

NASA Technical Reports Server

n 
National Aeronautics and Space Administration 
Goddard Space 1'1 i ght Ccnter 
Contract No AS- 5- 12487 - a'?i\- F 
Y S  
$$* ST - AP -AE - SPC - 10578 q\) 
TINTENSITY VARIATIONS OFbH, AND '111 6 583 A LINES 
c c  - ILd 
IN THE NIGHT SKY SPECTRUM { 
by 
( Jean Dufay 
Maurice Dufay 
Nguyen Huu-Doan 9 
D 
- -  
(ACCESSION NUMEER) 
(PAGES) 
(NASA CR O R  TMX OR AD NUMBER) 
(CATEGORY) 1 
https://ntrs.nasa.gov/search.jsp?R=19670012958 2020-03-16T18:34:03+00:00Z
ST- AP - AE -. SPC -10 578 
INTENSITY VARIATIONS OF Ha AND [N 111 6 583 A LINES 
IN THE NIGHT SKY SPECTRUM 
Comptes-Rendus de 
I 1'Academi.e des Sciences 
I Astrophysique et A6ronomie 
Paris, 16 Aoat 1961. 
Note by Jean Dufay 
Maurice Dufay 
C, Nguyen Huu-Doan 
SUMMARY 
The strong intensity variations of the lines and [N 111 6 583 A in 
the spectrum of the night sky are often the result of passage of galactic 
regions H I1 in the field of spectrographs. The line Ha , emitted in the 
interplanetary space or, more probably, in the upper atmosphere, can be iso- 
lated only outside the Milky Way. 
* 
* * 
1. The study of intensity variations of the line H, in the night sky 
E spectrum was pursued at the Haute-Provence Observatory (53'56". lat. , 23 
long.) with the aid of the grating spectrograph described in a preceding Note 
[l], the dispersion being 48 A / m ) .  
Eastman 103aE allowed us to abridge the exposures and to obtain a spectrum in 
a single night. 
from 12 January to 17 July 1961, by aiming at 15' of the North horizon. 
A preliminary slight fogging of films 
We thus obtained 28 spectrograms during the moonless nights 
All show the fine Ha line between the rotation lines Pl(3) and P2(4) of 
the band (6.1) of OH (Fig.1). 
January to March and passed through a maximum around the April newmoon (bet- 
ween 9 and 18 April). 
lized in June-July. 
Ha had almost reached that of the line [O,I] 6 364 A (Fig.lb). 
Its intensity increased rather reglarly from 
It then decreased more rapidly, seemingly having stabi- 
On 16 and 18 April the photographic intensity of the line 
Basing ourselves upon the absolute wcragr iztensities of the lines of the 
band (6.1) given by G. Kvifte [3], one may consider that at 15' of the hori- 
zon North the intensity of Ha roughly varied from 5 to nearly 20 Rayleighs. 
This is exactly the amplitude found under analogous conditions by V. S. Proku- 
dina at Zvenigorod (51'03' Lat.N) [4]. R. X. Haynoullina and Z. V. Kariahina 
[SI have measured at Alma-Ata in December 1957 and January 1958 for H, at 20' 
from the horizon intensities comprised between 4.1 and 6.4 Rayleighs. 
(*) Sur les variations d'intensit6 des raies Ha and [N 111 6 583 A 
dans le spectre du ciel nocturne. 
2. 
lhe line [N 111 6 583 A, visiblc on 15 of our negatives (January to May), 
is found to be enhanced simultaneously with the line II ,  , as already noted by 
Kvifte [3]  when he mentioned €or the first time the presence of [N 111 lines 
in the night sky spectrum. 
of which the intensity seems to be related to that of the line Ha. 
It is the sole radiation between 5 500 and 6 700 A 
The covariance of the lines Ha and 6 583 A naturally leads one to suspect 
the intervention of galactic regions H 11, where the emission of forbidden lines 
of ionized nitrogen generally accompanies that of hydrogen lines [6]. 
role may be important by virtue of the rather limited field of our spectrograph. 
Taking account of the angular aperture of the collimator, directly aimed at the 
sky, and of the length of the horizontal slot, the useful region of the sky cor- 
responds to an area of slightly more than 30 degrees-square (4.5' in height and 
about 7 O  in azimuth) and the regions H I1 of declinations between 58O45' and 
63'15' may cross the field in a little more than one hour. 
Their 
Had they been uniformly distributed, as an average, between two small cir- 
The curves 
cles parallel to the galactic plane, the intensity of H, would be proportional 
to the duration of the passage of the zone considered in the field. 
plotted by calculating for various epochs the duration of passage of the galactic 
zone comprised between the latitudes +lo' and -10' (for example) resemble effect- 
ively to the curve representing the variations of H, as a function of time: 
same gradual increase from January to April, same more rapid decrease afterward. 
The duration of the passage is maximum during the second fortnight of April. 
The brillant and extended regions of H I1 likely to pass in the field are 
Reference is principally made to the group of nebulosi- restricted in number. 
ties near N.G.C. 7635 ( c ( ~ 2 3 h 1 8 m ,  ~-%+60°49',  1961! ) ,  near I.C. 1805 
( a  = 2 h 3 1  In, 5 =+ 610 18'). 
The first group intervenes from January to the end of April, I.C. 1805 from 
February to the beginning of June, and I.C. 1848 from March till about 15 June. 
The duration of the passage is maximum for these regions in March-April. 
- \  
= + 61020') and near I.C. 1848 ( x  = 2 h 54 ni, 
We thus believe that the intensity variation of the line H,, observed in 
the Haute-Provence in the spring of 1961, stems at least in greater part from 
the !assage of galactic regions H 11. However, since the Milky Way no longer 
passes in the field in July, the line H, observed during that time and of which 
the intensity is weak and little variable, must indeed be of atmospheric. geo- 
coronal or interpanetary origin. 
3. Our measurements of radial velocity on the line H, seem to corroborate 
these conclusions despite their being of little precision. They seem signifi- 
cant when the line is strong. On 16 and 18 April we find -23 and -18 km/sec. 
Taking into account the orbital velocity of the Earth at the epoch, the radial 
velocities measured by G. Court& [7] by observing the interference rings of 
the line Ha lead to geocentric velocities -37.2 lun/sec for I.C. 1805 and -19.5 
h/sec for i.c. 1848. 
the order of +lo h/sec), the agreement is rather satisfactory. 
In view of the degree of our measurement precision (of 
'he less reliable measurements of February and July negatives give nearly 
zero radial velocities, as if the "terrestrial" phenomenon were then prevalent. 
d. 
Lo 
Fo 
u) 
n 
;3 . 
3 .  
OH P 
(9-3) (41 (5) 
0 
0 1  
K, 
u3 
n 
0 
H 
u 
a- 
b- 
A 
1 
R 
n n  
n 
Fig.1. 
a) Spectrum of 12 Januaty 1961, exp.of 09h.55 m. 
b) Spectrum of 18 April 1961, exp.of 06h.45m. 
4. 
4. The discussion oE Kvifte observations [3] makcs still more clearly 
apparent the contribution of regions I I  11. Thcir exposures were made at As 
(Norway, latitude 59'40' N), at various azimuths and heights, by projecting 
with the aid of a lens with short focal length the image of the sky on the ver- 
tical slot of the fixed spectrograph. 
generally allow the identification of the galactic regions observed. 
Brillant H I1 regions have passed in the field during all the exposures 
where the lines Ha and [N 111 6 583 A are intense and, contrary to author's 
opinion, the important enhancements of the two lines localized at certain 
points of the image of the slot, correspond well to the nebulosities of Orion 
and Cygnus. 
The indications given by the author 
We undertook analogous otxervations by projecting the image of the sky on 
the slot of our spectrograph mounted on an equatorial table that follows the 
diurnal motion, with a lens having a very short focus. 
obtained by aiming near ci Cygni (6 and 7 August 1961) show the lines Ha and 
6 58.'; A localized near Nebula America. 
[0 I] 5 577 and 6 300 A, that extend uniformly over the entire length of the 
slot. The duration of exposures (4h.45') was not sufficient to make appear 
the line Ha outside the nebulosities, not anymore than the bands OH. 
weakening of the "terrestrial" line near the zenith seems to be in favor of an at- 
mospheric origin rather than interplanetary or even geocoronal of the line Ha 
observed near horizon, beyond the Milky Way. It is not hown yet whether the 
lines of [N 111 are present in the spectrum of night glow, outside the regions 
H 11. 
The first two spectra 
Ha is much stronger than the lines 
The 
REFERENCES 
M. DUFAY J. DUFAY. Comptes-Rendus, 250, 4191, 1960. 
[2]. 
has for effect to weaken the line H, , which appears in absorption in lunar sky. 
The 1960 negatives, which do not show &in emission, have been influenced by a 
weak moonshine. 
N.B.  The presence of the Moon above horizon during part of exposure time 
[3]. Geofysiske Publikajoner, Oslo, 20 ,  No.12, 1959. 
[4]. J. DUFAY. Draft Rpeort, Internxtronom.Union, 191, 1961. 
[SI. 
[6]. N.B.  The presence of H on a night sky spectrum, of weak drjpersion, 
taken down in 1949, was already attributed to H I1 regions of Cygnus (J.CABA"ES, 
J. DUFAY F, M. DUFAY., C.R. 230, 1233, 1950). 
[ 7 ] .  
Ac.of Sc. of Kazakhstan. 1nform.of Astophysical Institute, 10, 52, 1960. 
Ann. d'Astrophysique, 2 3 ,  115, 1960. 
- 
r 
C o n t r a c t  No. NAS- 5 - 12487 
VOL'I' TLC1 INICN, CORPORATION 
1145 1'3th St.NW 
I). C. 20036. 
T e l :  223-6700; 223-4930. 
Translated by ANDRE L .  BRICHANT 
on 15 March 1967. 
G.S.F.C. 
100, 110, 400, 600, 601 
610 (2)  
611 vKB* + 6 
612 (6) 
613 (10) 
614 (6) 
615 (8) 
640 HESS 
0 ' KEEFE 
NORTHROP 
MEAD 
MAEDA 
HARRIS-HERRING 
CAMERON 
DISTRIBUTION 
N A S A  H Q S  
a l l  SG SS 
SL FELLOWS 
HIPSHER 
HOROWI TZ 
BRUNK 
SM FOSTER 
GILL 
RR KURZWEG 
RTR NEILL 
WX SWEET 
uss (2) 
BURLEX-KELSALL 
READING ROOM 
630 (3) 
620 SPENCER 
621 TAYLOR 
622 BANDEEN 
252 LIBRARY 
256 FREAS 
LHN VOLT 
" E L  
OTHER CENTERS 
A M E S  R C 
SONETT 
LIBRARY 
L A N G L E Y  R C 
116 KATZOFF 
160 ADAMSON 
235 SEATON 
185 WEATHERWAX 
JET PROP. LAB. 
186-133 SS 
183B-365 " B U R N  
111-127 LAWSON 
111-113 LIBRARY 
V i s . L a b  WYCKOFF 
U.MICH. 
HADDOCK 
MIT 
BARRETT 
-
+ a l l  permanent addressees 


Intensity Variations of H Alpha and N II 6 583 A Lines in the Night Sky Spectrum

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server