3 Discussion of the individual stars

3.1 Constant radial-velocity objects

Among the members of NGC 6231 observed in the present study, twelve stars show probably constant radial velocities. However this assertion is only preliminary for S248, #723, 726, and 749, because we could obtained only one observation per star. We nevertheless note that they fall close to the mean cluster velocity.

S238 (V964 Sco) a $\beta$ Cep variable, (Balona & Engelbrecht 1985). The four radial velocities obtained by LM83 varies by 20 km^-1 over four days, but ours were constant over the same range. S238 appears as a single star in the colour-magnitude diagram.

S248. The radial velocities of PHYB and our observation favour a constant radial velocity with a mean value of $<V_{\rm r}>$ = -33 km s^-1. This star appears to be single from the photometric analysis. Therefore, radial velocity and photometry leads to the conclusion that S248 is single.

S292 appears to be single both for the spectroscopy and the photometry. For comparison purposes, Fig. 8 shows the normalized CCD spectra, around the H$_{\gamma }$ line, as a template of a single, slow-rotating star, which can be compared to other non-symetric line profiles.

S293 This is a O9 Ib CNO star, which has probably constant radial velocity (Levato et al. 1988). We did not reobserve it.

S309 The V magnitude published by Raboud et al. (1997) has been replaced by that of Sung et al. (1998) who resolved S309 into two components (350 + 351, with magnitudes equal to 8.72 and 9.90 respectively). Star 350 is still 0.32 mag above the ZAMS although its radial velocity seems to be constant.

S343, The observations of PHYB, LM83, and ours are constant. The star is however 0.2 mag above the ZAMS.

The stars 723, 726 and 749 were observed for the first time in the present study, and the radial velocities, although based on one observation, support their membership to the cluster.

Moreover, stars 501, 724, 774 and 810 were also observed spectroscopically in the present work by the first time. The mean radial velocities are presented in Table 1.

 

 

Table 1: Fundamental data for stars brighter than V₀ = 9.0 ($V\; <$ 10.5) in NGC 6231

HD/CD	S	Sung	V0	X	$V\, \sin\, {i}$	Ref	$\overline{V_{\rm r}}$	$\epsilon$	N	Sp.T.	Ref	Phot	Notes
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)	(11)	(12)	(13)	(14)
152234	290	855	3.72	0.02	150	8	-37.5	2.9	37	B0 Iab	2	--	SB2O
152248	291	856	4.58	0.00	100+80	1	-26.6	3.8	8	O7 Ib:(f)	2	--	SB2O, EB
										+ O6.5:((f))
152249	293	857	4.78	-0.00	105	9				O9 Ib	2	--
152233	306	858	5.08	-0.00	130	9	-30.5	1.1	4	O6 III (f)	2	--	SB1
152270	220	854	5.11	-0.02						WC6 + O	4	--	SB2O
326331	338	571	5.76	0.01						O8 III	2	--	SB2O, M?
152218	2	853	6.00	0.04	140	3	-28.9	2.8	7	O9 IV	2	0.75	SB2O
152219	254	234	6.08	0.05	160	3	-26.3	4.3	8	O9.5 III	2	0.75	SB2O
152314	161	615	6.23	0.08	65	3	-21.5	5.8	3	O8.5 III	2	1.19	SB2, triple?
-41.11037	323	862	6.29	0.04	55	3				O9 III	2	0.52	SB1O
-41.11042	224	505	6.51	0.07	130	3	-17.6	6.8	8	O9 IV	2	0.75	SB2O
-41.11029	309	350	6.91	0.09	160	1	-32.9	1.3	2	O9.5 V	1	0.32
152200	266	206	6.97	0.06	210	3			5	O9.5 V(n)	2	0.00	SB2
326329	292	434	7.20	0.07	85	3	-45.2	5.5	3	O9.5 V	2	0.00
		314	7.39
	248	288	7.63	0.10	76	10	-36.1	1.8	1	B1 V	2	0.00
	287	403	7.80	0.27	< 40	3	-70.2	1.6	1	B1 V	2	1.05	SB1
326332	343	651	7.90	0.14	32	10	-23.5	2.3	2	B1 III	1	0.24
326327	28	113	7.94	0.16	150	3			2	B1.5 IVe+shell	2	0.33	SB2, triple?
	232	521	7.95	0.20	50	3	-70.8	4.9	3	B0.5 V	2	0.57	SB1, EB
	286	378	8.01	0.24	70	3			2	B0.5 V	2	0.69	SB2
326339	73	497	8.01	0.38						B0.5 III	6
326333	150	712	8.02	0.17	150	3	-47.1	2.8	2	B1 V(n)	2	0.31
326330	238	486	8.06	0.13	210	3	-29.8	0.7	2	B1 V(n)	2	0.00
V945 Sco	253	226	8.07	0.18	100+100	3			1	B1: V + B1: V	2	0.33	SB2
-41.11048	295	349	8.07	0.24	80	3	-24.7	1.6	6	B1 V	2	0.64	SB1
-41.11032	289	353	8.08	0.15	80	3	-38.7	3.9	7	B0.5 V	2	0.12	SB1
		351	8.08
-41.11056	110	653	8.10	0.15	190	1			2	B1 V	5	0.10	SB2
		578	8.14
-41.11030	272	334	8.15	0.21	98	10				B1 V	2	0.42	SB1
326340	70	374	8.16	0.15	100	1	-48.8	4.9	1	B0.5 V	6	0.00
	374	400	8.19	0.40
	282	268	8.32	0.28	80+80	3				B2 V: + B2 V:	2	0.55	SB2
V963 Sco	80	437	8.36	0.21	170	1	-37.3	4.3	1	B0 Vn	1	0.20
-41.11031	6	364	8.38	0.22	110	10	-22.1	5.3	3	B0 V	6	0.23
	112	684	8.46	0.19						B1 V	5
	312	346	8.58	0.26	<40	1	-13.6	5.1	3	B0 III	1	0.19	SB1
	330	456	8.59	0.31
326328	34	157	8.69	0.24	120	1	-45.9	3.9	2	B1.5 V	5	0.00	SB2?
-41.11028	261	303	8.76	0.27	140	1	-32.4	3.4	1	B2 IV	6	0.07	SB:
	294	461	8.90	0.46						B1.5 V	7
152235	501		3.10	0.06	< 40	1	-27.5	0.6	2	B1 Ia	1	--
	723		8.88	0.52	< 40	1	-39.3	3.2	1	B3: V	1	1.29	NM?
-41.10989	724		8.52	0.26	80	1	-21.5	2.5	2	B0: IV/V	1	0.30
-41.10990	726		8.57	0.30	90	1	-31.6	2.6	1	B1 V	1	0.40
	745		8.26	0.24	135	1	+61.1	6.4	1	B0 V	1	0.45	SB?
	749		8.55	0.30	160	1	-38.7	3.1	1	B1.5 V	1	0.40
-41.11051	769		7.28	0.15	145	1	-17.4	17.4	2	B0.5 V	1	0.90	SB
-41.11058	774		8.38	0.23	< 40	1	-32.2	0.4	2	B1: II/III	1	0.30
-41.11062	810		6.95	0.19	65	1	-26.7	3.6	2	B2 V	1	1.57	NM?

 

 

Table 2: Heliocentric radial velocities in NGC 6231

S	HJD	<RV>	pe	n
	-2400000	[km s-1]	[kms-1]
2	49910.730	-49.6	3.1	13
	49912.537	+80.3	15	6
	49914.473	-141.5	5.1	15
		+137.9	4.7	7
	49915.519	-105.1	4.3	20
	50594.809	-19.1	2.2	20
	50597.512	+16.5	4.6	12
	50598.866	-165.9	4.1	18
		+156.9	4.3	14
6	50594.794	-36.4	3.0	15
	50597.549	-20.4	2.3	15
	51361.772	-10.7	3.0	12
28	50595.694	-46.4	4.1	14
		-126.1	2.4	4
	50597.679	-29.6	3.7	13
		-115.7	3.2	6
34	50593.667	-41.4	2.7	11
	50597.665	-58.4	4.5	11
70	50598.660	-48.8	4.9	12
80	50598.622	-37.3	4.3	8
110	50595.853	-26.1	6.8	10
		-170.1	13:	6
	50597.871	-33.0	4.3	8
150	50595.760	-42.5	6.8	9
	50599.594	-49.7	5.1	8
161	50593.805	-31.5	1.6	21
		-137.7:	13	4
	50597.842	-37.6	2.7	24
	51300.738	-11.2	1.3	21
224	49912.743	+36.5	3.6	9
	49914.521	+127.5	3.2	15
	49915.538	-127.8	4.1	17
		+145.5	4.6	10
	49967.537	-94.8	4.0	22
	50594.680	+6.6	4.3	18
	50595.726	-129.2	6.0	12
		+193.0	7.8	11
	50597.827	-162.8	5.3	11
		+195.9	10:	2
	50598.811	+115.8	4.9	16
232	50594.751	-80.5	2.3	15
	50599.649	-65.8	2.1	17
	51362.593	-61.3	3.7	12
238	50594.696	-29.1	3.8	8
	50598.743	-30.5	3.1	12
248	50593.628	-36.14	1.8	21
253	50595.551	-108.9	7.5	10
		+164.7	9.1	8

 

Table 2: continued

Num. Id.	HJD	<RV>	pe	n
	-2400000	[km s-1]	[kms-1]
254	49910.751	-61.6	4.9	12
	49912.721	+45.5	3.9	12
	49914.499	-132.9	4.5	18
	49915.513	+14.9	3.6	17
	50593.600	-145.2	3.9	16
		+218.0	9.2	6
	50595.536	+78.9	7.6	14
		-251.5	15	2
	50597.900	-149.9	5.2	14
		+187.2		2
	50598.792	-51.2	2.6	15
261	50599.677	-32.4	3.4	11
266	49914.565	-28.5	3.1	14
	49915.557	+62.9	4.6	18
		-124.6	6.9	15
	49967.551	-0.8	3.9	11
	50595.825	+4.1	2.8	13
		-110.6	7.4	4
	50597.639	-26.9	5.0	15
286	50593.817	-11.2	2.3	16
		-100.7	2.8	3
	50597.588	+7.5	3.0	20
		-119.9	7.5	3
287	50593.853	-70.2	1.6	18
289	49914.671	-59.8	4.4	6
	49915.611	-34.7	2.1	17
	49966.517	-33.8	3.8	11
	49967.517	-62.3	4.0	12
	50594.578	-38.2	3.7	23
	50597.615	-38.2	3.1	14
	50598.829	-26.8	3.1	13
290	49910.695	-61.9	2.2	20
	49912.501	-86.0	2.5	25
	49914.074	-69.0	2.6	22
	50593.576	+13.5	2.3	23
		-116.8	10.3:	8
	50594.549	+18.0	1.2	30
		-142.6	7.3	19
	50595.508	+23.21	2.9	20
		-145.9	8.5	11
	50597.577	+13.25	1.7	25
		-130.2	9.9	7
	51361.731	-14.0	1.3	24
		-176.6	16.2	4
	51362.545	+0.5	1.3	31
		-166.7	9.7	10

 

Table 2: continued

Num. Id.	HJD	<RV>	pe	n
	-2400000	[km s-1]	[kms-1]
291	49910.715	+114.2	6.8	6
		-154.9	5.6	3
	49912.514	-97.6	7.5	10
	49914.463	-230.5	4.6	13
		+188.5	6.5	11
	50593.591	-183.4	3.7	11
		+144.9	3.5	12
	50594.565	-44.7	2.8	17
		-147.7	17.1	5
	50595.519	+121.4	4.3	10
		-174.2	7.7	5
	50598.518	-225.9	5.3	12
		+165.2	3.3	12
	51362.568	-49.2	5.0	12
292	50594.622	-34.4	2.8	20
	51300.812	-59.6	4.4	15
	51301.767	-47.8	2.0	17
295	49914.624	-30.6	1.9	19
	49915.576	-28.4	1.4	18
	49966.578	-23.9	1.8	20
	49967.579	-101.2	6.7	11
	50594.638	-31.5	1.8	27
	51301.809	-20.6	1.1	24
306	50594.556	-52.9	2.6	24
	51300.728	-43.7	2.3	14
	51361.745	-45.7	2.3	20
	51362.557	-45.5	2.3	17
309	50594.665	-26.8	4.5	14
	51300.783	-33.0	2.4	11
312	50597.522	-7.2	2.1	23
	50599.693	-0.8	1.6	19
	51362.646	-21.5	1.1	19
343	50595.807	-21.0	2.4	16
	50599.621	-25.9	2.0	21
501	50593.874	-28.3	1.4	23
	50597.706	-25.9	2.0	25
723	50595.606	-39.3	3.2	10
724	50595.643	-25.6	4.7	8
	50598.540	-19.2	3.5	7
726	50599.815	-31.6	2.6	12
745	50594.836	+61.1	6.4	9
749	50599.722	-38.7	3.1	14
769	50594.890	+2.7	2.1	13
	50597.758	-71.3	3.4	13
774	50597.808	-31.8	1.5	19
	50599.849	-33.9	3.1	18
810	50597.719	-31.6	3.2	14
	50598.690	-30.1	2.1	15

3.2 Probable single-lined spectroscopic binaries

S6. Our three radial velocities suggest that S6 is a spectroscopic binary. Furthermore, they differ by 30 km s^-1 from those obtained by PHYB. The star is 0.25 mag above the ZAMS.

S34. This star raises a problem because it appears to be single in the CM diagram, but the line profiles are probably asymetric, as show by Figs. 9 and 10, which would indicate the presence of a companion. In any case, the radial velocity is variable. We assume that the variability is due to the binary nature rather than to line intrinsic variability.

S70. PHYB found a velocity dispersion of 42 km s^-1 and a mean velocity $<V_{\rm r}>$ = -26 km s^-1. This scatter may be due to the possible binary nature, which is supported by our observation, 20 km s^-1 more negative. However, S70 appears to be single from the photometry.

S80. PHYB found $\Delta V$ = 25 km s^-1, with a $<V_{\rm r}>$ = -26 km s^-1. Our velocity is 10 km s^-1 more negative. The stars is about 0.25 mag above the ZAMS. It could be a long period binary.

S150 (V920 Sco), a $\beta$ Cep variable, (Balona 1983) appears to be 0.3 mag above the ZAMS. The scatter observed by LM83 and the fact that our mean velocity is 10 km s^-1 more negative than the cluster velocity lead us to conclude that S150 is also a probable binary.

S272 From three observations, Levato & Morell (1983) concluded that this star is a spectroscopic binary. This suspicion is confirmed by the position of S272 in the colour magnitude diagram, about 0.65 mag above the ZAMS. Further observations are required and will be obtained.

3.3 Confirmed single-lined spectroscopic binaries

S232. Proposed as a long-period variable by Balona (1983), this star is in fact an eclipsing binary (Balona & Engelbrecht 1985). Our observations confirm the duplicity suspected from the data from LM83. It is about 0.55 mag above the ZAMS and should be detected as a double-lined binary. S232 (V = 9.65, B-V = +0.23) is a good candidate to derive a mass for a B0.5V star.

S261. V946 Sco, a $\beta$ Cephei variable (Balona 1983). This object was observed by PHYB and Raboud (1996); for the first authors the average of the radial velocity is -9 km s^-1, and for Raboud, the same value (-10 km s^-1), but with a dispersion of 29 km s^-1. Raboud proposed that this star is a spectroscopic binary. In the present study, we have only one measure of this star (-32.4 km s^-1), but it differs from the previous observations by 20 km s^-1, and we conclude that S261 is a binary, although it appears to be single in the CM diagram.

S287. Our observation $V_{\rm r}$ = -70 km s^-1 differs by 50 km s^-1 from the values published by LM83 and Raboud (1996). Photometrically, it appears as a triple system, 0.25 mag above the binary ridge. We conclude that this star is another binary or multiple member of the cluster.

S289. LM83 found, from four spectrograms, a radial-velocity range of 60 km s^-1. We found, based on seven spectrograms $\Delta v$ = 40 km s^-1. S289 is obviously a spectroscopic binary which also appears as a single star in the CM diagram. We have obtained a preliminary period of 8.863 days for this star (see Table 3, and Fig. 1 - Sung 353).

S295. Levato & Morrell detected a variable-radial velocity. Our spectra allow us to confirm this behaviour, although we are not able to derive orbital elements for this star. It is about 0.65 mag above the ZAMS and should be seen as a double-lined binary.

S306. HD 152233 is a blue straggler (Mermilliod 1982) and a proposed variable star (Balona 1992). Fullerton (1991) reports small radial-velocity shifts and Fullerton et al. (1996) included this object in their O-type star sample for the study of the absorption-line profile variations. These authors found -13.7, -19.9 and -27.4 km s^-1 for the radial velocity of CIV $\lambda$5801, CIV $\lambda$5812, and HeI $\lambda$5876, respectively, observed between the JD 2446605.5 and 2446611.5. Although their data seem to be constant, their mean RV differs from the mean cluster velocity. From all published data, the star is definitely a binary and we determined a preliminary orbit (Fig. 1f), with a period of 4 $\hbox{$.\!\!^{\rm d}$ }$15. Further observations are needed to confirm the period.

S312. This star is another SB1 system. There are some evidence of a second component, but no definitive conclusion can be derived from our spectrograms. It is 0.20 mag above the ZAMS and hence probably a binary.

R745. We have only one spectrum for this star, but the radial velocity (+61 km s^-1) suggests that it is a spectroscopic binary, because its photometry and spectral classification favour its membership. It is located 0.5 mag above the ZAMS, and should be a binary, if member.

3.3.1 Probable double-lined spectroscopic binaries

The stars 28, 110, 161, 253, 266, and 286 present the following characteristics in their spectra:

S28. This is V692 Sco a $\beta$ Cep variable (Balona & Engelbrecht 1985). LM83 suspected the binary nature of this object. The line profile (Fig. 12) shows the presence of a broad secondary component on the left wing of the H$_{\beta }$ line. Both spectra show the same feature. Because the velocity of the main component is close to the cluster velocity, this star should be triple. In the CM diagram, S28 is 0.3 mag above the ZAMS.

S110 This is V497 Sco, another $\beta$ Cep variable star, (Balona 1983). On JD 2450595.694, we see a secondary component in the middle of the left wing. Figure 13 shows the H$_{\beta }$ line profiles on each spectrum. The upper profile is symetric, while the lower one clearly contains a secondary component. Figure 14, plotted with a different scale, enhances the asymetry of the profile. The star is located very close to the ZAMS, which raises a problem. The velocity of the main component is close to the cluster mean velocity.

S161. Feinstein & Ferrer (1968) found that this star is variable in luminosity and Raboud et al. (1997) obtained a period of about 20 years, with a peak to peak amplitude larger than 0.1 mag. Based on the four radial velocities obtained by LM83 and our three observations, this star is clearly a binary, but the period is much shorter than 20 years. On JD 2450593.805, we detected a probable secondary spectrum on the left wing (Fig. 15). More observations are needed in order to confirm this finding. Photometrically, S161 is also clearly double, and could even be a triple system. The rather slow rotation ($V\sin i$ = 65 km s^-1) cannot explain the position above the binary ridge.

Figure 1: Radial velocity curves for 6 spectroscopic binary systems in NGC 6231. Primary observations are indicated by filled squares, secondary, by open squares, points rejected from the solutions by diamonds or crosses

S253. This star was classified as SB2 by Levato & Malaroda (1980). LM83 confirmed the SB2 character, but measured the velocity of the primary only. On our spectrogram, the presence of both component is evident as shown by Fig. 16. The star is 0.3 mag above the ZAMS and hence obviously double.

S266. LM83 found it to be a single-lined spectroscopic binary. On two among five spectra, we detected double lines (Fig. 17). Proposed as variable star by Feinstein & Ferrer (1968) with a range of 0.07 mag, this star appears to be single in the CM diagram.

S286. The radial-velocity difference between the observations of LM83 and later data obtained by Raboud (1996), $\Delta V_{\rm r}$ = 30 km s^-1 indicates that this star is a binary. On both of our spectra, the lines are double, as is exemplified by Fig. 18 for the HeI $\lambda$ 4471 line profiles. This is in good agreement with the position in the CM diagram, about 0.7 mag above the ZAMS.

323. This star has not been reobserved. Orbital elements have been determined by HCB, and revised by LM83. The period is P = 5 $\hbox{$.\!\!^{\rm d}$ }$74.

R769. The radial-velocity difference between our two spectrograms amounts to $\Delta V_{\rm r}$ = 74 km s^-1 and this star is definitely a spectroscopic binary. As is shown by Fig. 11 the profiles of the H$\gamma$ line are clearly asymetric, which is probably due to the presence of the secondary. It is an obvious PHB, 0.75 mag above the ZAMS.

It is very important to note, that we have only one or two spectra for several stars of our sample. For this reason, it will be necessary to obtain additional observations to confirm our conclusions.

3.3.2 Double-lined systems with calculated orbits

The stars 2, 224, 254, 290 and 291 present well defined double-lined spectra. For these stars we have improved the periods, and estimated new orbital elements, using the code developed by Imbert at the Marseille Observatory and routinely used at the Geneva Observatory in the Coravel group.

S2 - HD 152218, O9IV This star was proposed as binary by Struve (1944). The first period obtained by HCB, was P = 5.4 days. LM83 proposed $P = 5\hbox{$.\!\!^{\rm d}$ }5009 \pm$ .0003. Stickland et al. (1997) determined a period of $P = 5\hbox{$.\!\!^{\rm d}$ }$6040 by combining optical and IUE radial velocities. The combined optical observations favor a period of 4 $\hbox{$.\!\!^{\rm d}$ }$8925. The orbital curve for all optical and IUE data for $P = 5\hbox{$.\!\!^{\rm d}$ }$604 does match well all observations. The IUE observations better cover the whole cycle and better constrain the eccentricity. We give the optical period in Table 3, the RV curve is plotted in Fig. 1c. The H$_{\delta}$ line profiles at three different phases demonstrate the line doubling (Fig. 2).

S220 - HD 152270, WC6 + O has not been reobserved because good orbital elements have been obtained by Seggewiss (1974), with a period of P = 8 $\hbox{$.\!\!^{\rm d}$ }$89.

S224 - CPD -41 $\hbox {$^\circ $ }$7742, O9IV The orbital elements for this star were first estimated by HCB, and by LM83. We obtained eight new observations and recomputed the orbital elements (Fig. 1b). We confirm the short period but find a higher eccentricity. Figure 3 presents the variation of the H$_{\delta}$ line profiles at three different phases. The secondary component is best visible on the right wing of the upper spectrum ($\phi$ = 0.356). The position is the CM diagram indicates a location close to the binary ridge.

S254 - HD 152219, O9.5III Orbital elements have been published by HCB and by LM83. Our period, based on all published data and our eight additional observations is shorter by 0 $\hbox{$.\!\!^{\rm d}$ }$10 (Fig. 1a). The presence of the secondary is seen on the line profile at phase $\phi$ = 0.599 (Fig. 4, lower spectrum) and produces the enhancement of the line width. Located close to S2, this star is clearly double from the photometry.

  

Table 3: New orbital elements

$$\begin{tabular}{lr@{.}lr@{.}lr@{.}lr@{.}lr@{.}lr@{.}lr@{.}l} ... ...ticolumn{2}{c}{33}\\ \noalign{\smallskip }\hline \end{tabular}$$

S282, B2V + B2V. SB2 discovered by Levato & Malaroda (1980) and confirmed by LM83. Not reobserved.

S290 - HD 152234, B0Iab. This is the brightest star in the cluster classified as a CNO-type star. It was observed by Campbell & Moore (1928), Struve (1944), LM83, and Levato et al. (1988) who proposed a period of around 27.25 days. In the present study, we confirm the binary nature of this star and propose preliminary orbital elements at 54 $\hbox{$.\!\!^{\rm d}$ }$46, twice as long (Fig. 1d). The secondary component has been observed at several phases (Fig. 5). S290 is in addition a visual binary (AB: 0 $\hbox{$.\!\!^{\prime\prime}$ }$5).

S291 - HD 152248, O7Ib:(f) + O6.5:((f)). This star has been detected since the first observations by Struve (1944) as a double-lined system. HCB found a solution for both components. They derived a period around 5.97 days, by assuming a nul eccentricity. On the other hand, LM83 reported another solution for the orbital elements, with a period not so different from the obtained in the HCB paper (P = 5.89144 $\pm\ 4 \ 10^{-4}$) but with an eccentricity of e = 0.18 $\pm$ 0.02. Stickland et al. (1996) derived orbital elements from IUE spectra (P = 5 $\hbox{$.\!\!^{\rm d}$ }$81), revised by Penny et al. (1999). In the present study, we have recomputed the orbital parameters with all available observations, $P = 5\hbox{$.\!\!^{\rm d}$ }$75, e = 0.13. (Radial-velocity curve not represented in Fig. 1). This star is an eclipsing binary (Mayer et al. 1992) and has a third companion, Chara 252 Aa (0 $\hbox{$.\!\!^{\prime\prime}$ }$05), with a period estimated to 150 yr by Mason et al. (1998). The line profiles at different phases are shown in Fig. 6.

338, HD 326331, O8III. Orbital elements by LM83, with a period P = 6 $\hbox{$.\!\!^{\rm d}$ }$42. We have not reobserved it so far, but we shall do it.