The object of this communication is to discuss the spectrograms of this star, obtained at Bosque Alegre (Córdoba Observatory) between 1955 and 1959- There are 27 measurable spectra available, well distributed over the different phases.
In each plate 28 lines were measured, selected from those recommended by the Victoria observers, for the 30 and 50 A/mm dispersion, since our plate dispersion is 42 A/mm. If instead of these lines one measures those used by Stibbs, one gets a systematic difference of +1.2 km/sec. The mean probable error of our plates is of the order of 1.5 km/sec.Asociación Argentina de Astronomí

Jaschek, Carlos

Kucewicz, B.

English

Kucewicz, Boris

Servicio de Difusión de la Creación Intelectual

THE RADIAL VELOCITY OP 1 CARIRAEB.Kucewvjz and C.Jaschek (Observatorio Astronómico,La Plata)The. object of this communication is to discuss the spectrograms of this star, obtained at Bosque Alegre (Córdoba Observatory) between 1955 and 1959« There are 27 measurable spectra available, well distri­buted over the different phases.In each plate 28 lines were measured, seleoted from those recom­mended by the Victoria observers, for the 30 and 50 A/mm dispersion, since our plate dispersion is 42 A/mm. If instead of these lines one measures those used by Stibbs^, one gets a systematic difference of +1.2 km/sec. The mean probable error of our plates is of the order of 1.3 km/sec. The result of the measurements is given in table I.Table IRadial velocity observationsN J.D. <P V N J.D. <P VI 2273 2435172,57 0,35 - 0,3 2528 2435453,74 0,26 -14,62326 183*58 66 +11,4 2546 458,73 40 - 0,62327 183,60 66 +12,7 2572 497,81 50 + 4,82339 187,64 78 +13,2 2615 509,76 84 + 3,02340 187,65 78 + 9,7 2622 510,73 86 + 6,72349 190,60 86 + 8,8 2885 36234,74 23 -17,62356 192,56 92 -25,4 2886 234,77 23 -16,92366 194,55 97 -24,5 2894 235,77 26 -17,82477 441,76 92 -23,0 2905 242,64 45 + 5,12478 441,76 93 -26,2 2924 243,66 48 + 6,02495 448,80 12 -24,8 2936 244,67 51 + 1,32504 449,81 15 -14,4 2954 245,76 54 +11,22511 450,76 18 -20,8Por the representation of our measurements (fig.l) we used thevalue of the period given in the 1958 edition of the GENERAL CATALOGUEOP VARIABLE STARS, namely 35d556. The general aspect of the curve is2 )remarkably similar to the curve published by Jaschek and Jaschek ,basedon about half of these plates. In order to evaluate the systematicdifferences, we have formed the difference"Kucewicz - Jaschek"for the eleven plates in common. Their mean difference is Í 1.0 km/sec.We will now compare the present radial velocity curve with those4) 1)published earlier. There are four: Wilson and Huffer , Jacobsen ,3) 2)Stibbs and Jaschek and Jaschek . Plotting the curves for different50epochs, namely Wilson and Hufier (1904-07); Jacobsen (1918)»Jacobsen (1920); Stibbs (1952), and the present work, we get very similar curves, with the exception of the one by Stibbs, which is very different. In order to get a quantitative idea of the differences among the curves, we will assume that the radial velocity curve of this Cepheid is the one of a spectroscopic binary. This procedure is of course artificial, since no physical reality can be attached to the elements. The useful­ness of the procedure consists in the fact that Buffer and Wilson and Jacobsen did published such elements. Computing elements for the later curves, by the usual procedure, we get the following dataAuthor Wilson and Huffer Jacobsen Stibbs PresentMean epoch 1905 1919 1952 1956K 19 km/sec 18 18,5 19e 0.36 0.43 0.19 0.48100 100 94 101V0 +4.1 km/sec +2.5 +1.5 -5.3barycentral velocity (V0) is very different and that only in the case of Stibbs' curve the shape is essentially different. As far as to the barycentral velocity, it must be remembered that our value has not been reduced to the Lick system, so that we have still a systematic error in it, and therefore not too much weight should be attached to this.The different shape of the Stibbs curve is due mostly to two observa­tions near the maximum. If these two ware eliminated (which is of course not feasible) all the curves would b.. very much alike.Prom this evidencealone one can therefore not conclude whether the radial velocity curve is variable or not.We have however an additional element, namely the period.In the GENERAL CATALOGUE OF VARIABLE STARS (1958 ed.) it is mentioned that the period has been changed at least three times. The following values are quotedPrager and Schneller (1934) 35d54General Catalogue (1948) 35 5323General Catalogue (1958) 35 556A short analysis of the radial velocity curve reveals howeverthe curious fact that none of these periods satisfies the radialvelocity observations. Prom the observed maxima and minima, the periodshould be35d5374value which is irreconciliable with the light observations.One is therefore forced to conclude that the period and perhaps also the shape of the radial velocity curve is variable. More observa­tions are thus needed, which we hope to undertake at La Plata in I960.1) Jacobsen T.S., Publ. A.S.P. ¿¡6 , 255 (1934)2 ) Jaschek K. me’ Jaschek C. Publ. A.S.P. 69 . 465 (1957)3) Stibbs D.W.W., K.N. 11£, 363 (1955)4) Wilson E.R., na Huffer C.M., Pop.Astr. £2» 85 (1921)Disousión:GRATTON criticó el uso de elementos espectroscópicos orbita­les para estrellas pulsantes.52

The radial velocity of 1 Carinae

SEDICI - Repositorio de la UNLP

THE RADIAL VELOCITY OP 1 CARIRAE
B.Kucewvjz and C.Jaschek 
(Observatorio Astronómico,La Plata)
The. object of this communication is to discuss the spectrograms 
of this star, obtained at Bosque Alegre (Córdoba Observatory) between 
1955 and 1959« There are 27 measurable spectra available, well distri­
buted over the different phases.
In each plate 28 lines were measured, seleoted from those recom­
mended by the Victoria observers, for the 30 and 50 A/mm dispersion, 
since our plate dispersion is 42 A/mm. If instead of these lines one 
measures those used by Stibbs^, one gets a systematic difference of 
+1.2 km/sec. The mean probable error of our plates is of the order 
of 1.3 km/sec. The result of the measurements is given in table I.
Table I
Radial velocity observations
N J.D. <P V N J.D. <P V
I 2273 2435172,57 0,35 - 0,3 2528 2435453,74 0,26 -14,6
2326 183*58 66 +11,4 2546 458,73 40 - 0,6
2327 183,60 66 +12,7 2572 497,81 50 + 4,8
2339 187,64 78 +13,2 2615 509,76 84 + 3,0
2340 187,65 78 + 9,7 2622 510,73 86 + 6,7
2349 190,60 86 + 8,8 2885 36234,74 23 -17,6
2356 192,56 92 -25,4 2886 234,77 23 -16,9
2366 194,55 97 -24,5 2894 235,77 26 -17,8
2477 441,76 92 -23,0 2905 242,64 45 + 5,1
2478 441,76 93 -26,2 2924 243,66 48 + 6,0
2495 448,80 12 -24,8 2936 244,67 51 + 1,3
2504 449,81 15 -14,4 2954 245,76 54 +11,2
2511 450,76 18 -20,8
Por the representation of our measurements (fig.l) we used the
value of the period given in the 1958 edition of the GENERAL CATALOGUE
OP VARIABLE STARS, namely 35d556. The general aspect of the curve is
2 )
remarkably similar to the curve published by Jaschek and Jaschek ,based
on about half of these plates. In order to evaluate the systematic
differences, we have formed the difference
"Kucewicz - Jaschek"
for the eleven plates in common. Their mean difference is Í 1.0 km/sec.
We will now compare the present radial velocity curve with those
4) 1)published earlier. There are four: Wilson and Huffer , Jacobsen ,
3) 2)Stibbs and Jaschek and Jaschek . Plotting the curves for different
50
epochs, namely Wilson and Hufier (1904-07); Jacobsen (1918)»Jacobsen 
(1920); Stibbs (1952), and the present work, we get very similar curves, 
with the exception of the one by Stibbs, which is very different. In 
order to get a quantitative idea of the differences among the curves, 
we will assume that the radial velocity curve of this Cepheid is the 
one of a spectroscopic binary. This procedure is of course artificial, 
since no physical reality can be attached to the elements. The useful­
ness of the procedure consists in the fact that Buffer and Wilson and 
Jacobsen did published such elements. Computing elements for the later 
curves, by the usual procedure, we get the following data
Author Wilson and Huffer Jacobsen Stibbs Present
Mean epoch 1905 1919 1952 1956
K 19 km/sec 18 18,5 19
e 0.36 0.43 0.19 0.48
100 100 94 101
V0 +4.1 km/sec +2.5 +1.5 -5.3
barycentral velocity (V0) is very different and that only in the case 
of Stibbs' curve the shape is essentially different. As far as to the 
barycentral velocity, it must be remembered that our value has not been 
reduced to the Lick system, so that we have still a systematic error 
in it, and therefore not too much weight should be attached to this.
The different shape of the Stibbs curve is due mostly to two observa­
tions near the maximum. If these two ware eliminated (which is of course 
not feasible) all the curves would b.. very much alike.Prom this evidence
alone one can therefore not conclude whether the radial velocity curve 
is variable or not.
We have however an additional element, namely the period.In the 
GENERAL CATALOGUE OF VARIABLE STARS (1958 ed.) it is mentioned that 
the period has been changed at least three times. The following values 
are quoted
Prager and Schneller (1934) 35d54
General Catalogue (1948) 35 5323
General Catalogue (1958) 35 556
A short analysis of the radial velocity curve reveals however
the curious fact that none of these periods satisfies the radial
velocity observations. Prom the observed maxima and minima, the period
should be
35d5374
value which is irreconciliable with the light observations.
One is therefore forced to conclude that the period and perhaps 
also the shape of the radial velocity curve is variable. More observa­
tions are thus needed, which we hope to undertake at La Plata in I960.
1) Jacobsen T.S., Publ. A.S.P. ¿¡6 , 255 (1934)
2 ) Jaschek K. me’ Jaschek C. Publ. A.S.P. 69 . 465 (1957)
3) Stibbs D.W.W., K.N. 11£, 363 (1955)
4) Wilson E.R., na Huffer C.M., Pop.Astr. £2» 85 (1921)
Disousión:
GRATTON criticó el uso de elementos espectroscópicos orbita­
les para estrellas pulsantes.
52


http://sedici.unlp.edu.ar/bitstream/handle/10915/74384/Documento_completo.pdf?sequence=4

The radial velocity of 1 Carinae

Abstract

Similar works

Full text

Available Versions

Servicio de Difusión de la Creación Intelectual

SEDICI - Repositorio de la UNLP