2. Observations and reduction

2.1. Observations

The first difficulty we encounter in a study on the Bootis stars is that of establishing a list of candidates. Not all the Bootis classifications are based on the same criteria, although Gray (1988) has proposed a clear working definition. The stars selected for our survey come from those recognised as being Bootis stars according to spectroscopic criteria. Our first sources were Gray (1988) and Gray & Garrison (1987, 1989a,b). We subsequently used three other papers by Abt (1984), Abt & Morrell (1995) and Andrillat et al. (1995). Such a choice can obviously reveal some disagreement between these authors, our Table 1 (click here) showing that many stars considered as Bootis by Abt or Abt and Morrell are not classified Bootis by Gray and Garrison.

According to Gray (1988) some stars were classified in the literature as Bootis on the basis of a weak MgII 4481 line, but some other groups of stars display the same feature, as for example many Ap and helium-weak stars. Thus we can understand why some stars classified Bootis by Abt are classified Ap by other authors.

The above discussion shows the difficulty in selecting real Bootis stars. Some authors (Baschek et al. 1984; Faraggiana et al. 1990) have used UV criteria, but due to the small number of stars in their sample it is not sure if they really are a general property of Bootis stars. Faraggiana (1987) well resumed the situation before the work of Gray (1988), while Gerbaldi & Faraggiana (1993) have produced a list of what we could call real Bootis stars. However, such a list would now need to be revised by adding new stars.

It may be seen from Table 1 of Gerbaldi & Faraggiana (1993) that among the stars of our Table 1 (click here) the following are considered to be real Bootis stars: HD 31295, HD 38545, HD 110411, HD 111604, HD 125162 and HD 221756. A survey of the literature allows us to propose some more stars: HD 36496, HD 39283 from Andrillat et al. (1995), while HD 217782 was proposed by Parenago (1958) as a Bootis star and this property was confirmed by Andrillat et al.

It will be seen in Sect. 3 that we propose the exclusion of four stars from the Bootis group: HD 47152, HD 108283, HD 204965 and HD 225180. HD 159082 and HD 196821 are also classified as HgMn stars and, taking into account the remark of Gray (1988), they may also be excluded. The status of HD 112097 is not very clear. This star is classified as Am by Levato & Abt (1978) and is classified F0Vp ( Bootis, met: A7) by Abt & Morrell (1995). Photometric data (see Sect. 3) agree with Bootis type, this star being slightly metal-deficient. HD 110377 is found to be a Sct star by Peniche et al. (1981).

The remaining stars have either an alternate classification or are classified only by Abt (1984) or Abt & Morrell (1995). Gray & Garrison (1987, 1989a,b) have classified the following stars as normal, while Abt or Abt and Morrell classified them as Bootis: HD 11503, HD 16811, HD 30739, HD 118623, HD 125489, HD 153808, HD 161868, HD 210418, HD 214454 and HD 220061.

HD 34787 is classified as Bootis by Abt & Morrell (1995), while Faraggiana et al. (1990) have excluded it. Finally HD 2904, HD 5789 and HD 109980 are classified as Bootis only by Abt and Morrell and HD 141851 by Abt. Such an enumeration of disagreement clearly shows the necessity for a critical survey by a spectroscopic specialist of all Bootis stars and Bootis candidates. Since the submission of this paper, a consolidated catalogue of Bootis stars has been lately published (Paunzen et al. 1997) and surely it could play this role.

Some of these stars are already mentioned in the literature as having circumstellar matter. They are HD 38545 (Stürenburg 1993; Bohlender & Walker 1994, Paper I), HD 39283 (Andrillat et al. 1995), HD 108283 (Jaschek et al. 1991) and HD 217782 (Andrillat et al. 1995). Concerning HD 31295, HD 110411 and HD 221756, Stürenburg (1993) mention the presence of a marginal shell. For some stars of our sample an IR excess is mentioned in the literature. King (1994) has found such an excess for HD 31295, HD 125162 and HD 161868 and a marginal excess for HD 111604. Cheng et al. (1995) find an IR excess for HD 110411.

Our observations were made during four sessions at the Haute-Provence Observatory in November 1994, February 1995, May 1995 and October-November 1995, using the 1.52 m telescope equipped with the AURELIE spectrograph. The detector is a double-element TH7832 with sets of 2048 photodiodes of . Two gratings were used ( 7 with 1800 lines/mm and 2 with 1200 lines/mm). More details on AURELIE can be found in Gillet et al. 1994).

Table 1 (click here) lists the stars observed during the four sessions, together with some of their characteristics. The fourth column, S1, gives the source of Bootis classification. Spectral types are from Abt and Morrell (Col. 6) and Gray and Garrison (Col. 7). Radial velocities are from the Bright Star Catalogue (Hoffleit & Jaschek 1982), while is taken from Abt & Morrell (1995) and photometric data, including m_v, are taken from the Geneva Database. Table 2 (click here) gives a record of the new observations, the latter being made in the following spectral regions: , CaII-K, NaI-D and for a few stars, at and .

 

name HR HD S1 V Sp Sp S2 RV B2-Vl d Abt & Morrell

129 2904 3 6.42 A0Vn 2 -10 225: -0.149 1.480 0.461 9400

283 5789 3 6.04 B9.5Vn 2 +lSB 230:

545 11503 3 4.83 B9.5IVn 1 +4V 185

793 16811 2 5.73 A0Vn A0IVn 1 -7V 160 -0.161 1.446 0.444 9500

1137 23258 3 6.10 A0V 2 +15SB 110 -0.141 1.381 0.494 9300

1544 30739 3 4.36 A0.5IVn 1 +24SB 195 -0.136 1.542 0.539 9200

1570 31295 1 4.65 1 +13V 105 -0.091 1.372 -0.010 0.524 8800

16 Cam 1751 34787 3 5.23 A0Vn 2 +12SB 200: -0.163 1.534 0.458 9400

1853 36496 4 6.26 A5Vn A8Vn 2 -15V? 180 0.034 1.196 -0.029 0.354 7700

131 Tau 1989 38545 1 5.72 A2IVn+sh 1 +21V 175 -0.087 1.526 -0.015 0.588 8700

2029 39283 4 4.99 A1IVp A1Va 1 -12V? 55 -0.115 1.492 0.598 9000

53 Aur 2425 47152 3 5.79 B9np 2 +18V? 25 -0.161 1.368 0.413 9500

14 Com 4733 108283 3 4.95 A9IVnpSr 1 -4SB1 85 0.081 1.419 0.018 0.539 7400

9 CVn 4811 109980 3 6.37 A7Vn 2 -15 255: 0.006 1.272 -0.023 0.445 7900

27 Vir 4824 110377 3 6.19 A7Vn 2 +9SB 160 0.010 1.266 -0.038 0.401 7900

4828 110411 1 4.88 A0Vp 1 +2SB 140 -0.092 1.407 -0.021 0.525 8800

4875 111604 2 5.89 A3V 2 -14V 180 -0.007 1.415 -0.037 0.482 8000

41 Vir 4900 112097 3 6.25 B9III 2 -l0SB 61 0.080 1.127 -0.020 0.283 7400

25 CVn 5127 118623 3 4.82 A7Vn 1 -6V1 90 0.040 1.280 -0.017 0.420 7600

5351 125162 1 4.18 1 -8 110 -0.081 1.400 -0.013 0.546 8700

5368 125489 3 6.19 A7V 1 -22V 145

36 Ser 5895 141851 2 5.11 A3Vp(*)n A3Vn 2 -8V 185 -0.049 1.388 -0.041 0.491 8400

6324 153808 3 3.92 A0IV 1 -25SBO 50 -0.161 1.394 0.409 9500

6532 159082 3 6.42 B9.5V 2 -12SBO 30

6629 161868 2 3.75 A0Vp(*)n A0Van 1 -7SB? 185 -0.124 1.459 0.549 9000

7903 196821 3 6.08 A0III 2 -37SB? 10 -0.185 1.522 0.426 10200

8237 204965 2 6.02 A2Vp(*) A3V 2 -17SB 85 -0.090 1.606 0.005 0.672 8700

8450 210418 2 3.53 A2V A2m1IV-V 1 -6SB2 130 -0.086 1.461 -0.013 0.564 8700

9 Lac 8613 214454 3 4.63 A7IV-V 1 +12SB 93 0.050 1.298 -0.003 0.453 7600

2 And 8766 217782 4 5.10 A1V A3Vn 2 +2SB 195 -0.075 1.567 -0.023 0.605 8600

8880 220061 2 4.60 A5V 1 +16V 135 -0.005 1.382 -0.019 0.507 8000

15 And 8947 221756 1 5.59 A1Vp(*) 1 +13V 75 -0.089 1.459 -0.002 0.595 8700

9 Cas 9100 225180 3 5.88 A1II-III 1 -18V 25 0.259 1.805 0.798 Notes to table Sources of spectral types, column 8: 1. Gray & Garrison (1987, 1989a,b) 2. Cowley et al. (1969) ^* in column 6 is for 4481 wk.

 

 

star line(s) date HJD-2400000 exposure resolution S/N

HD d/m/y time (min.)

2904 01/11/95 50023.480 158 14000 180

5789 31/10/95 50022.417 105 14000 450

NaID 02/11/95 50024.469 120 21000 320

11503 10/11/94 49667.420 43 23000 380

11/11/94 49668.389 47 25000 470

16811 30/10/95 50021.474 76 14000 390

NaID 03/11/95 50025.419 132 21000 420

23258 01/11/95 50022.585 98 14000 300

NaID 03/11/95 50025.551 164 21000 300

30739 11/11/94 49668.436 66 25000 430

31295 11/11/94 49668.510 66 25000 450

34787 01/11/94 49667.563 62 23000 350

02/11/95 50023.675 108 14000 280

12/11/94 49668.556 62 25000 420

NaID 03/11/95 50024.559 65 21000 460

36496 31/10/95 50021.632 120 14000 270

38545 11/11/94 49667.630 113 23000 350

12/11/94 49668.653 102 25000 430

NaID 04/11/95 50025.662 150 21000 300

39283 31/10/95 50021.694 43 14000 210

05/11/95 50026.677 101 17000 600

NaID 03/11/95 50024.606 64 21000 480

47152 01/11/95 50022.656 89 14000 160

NaID 03/11/95 50024.673 120 21000 150

108283 05/05/95 49843.363 96 23000 350

NaID* 08/05/95 49846.356 60 34000 400

109980 NaID 10/05/95 49848.389 167 34000 420

110377 NaID 09/05/95 49847.383 167 34000 470

110411 06/05/95 49844.382 111 23000 450

07/02/95 49755.582 19 15000 430

10/02/95 49758.608 38 17000 500

NaID 08/05/95 49846.404 59 34000 520

10/02/95 49758.671 23 23000 380

111604 07/05/95 49845.395 161 23000 380

07/02/95 49755.614 46 15000 420

112097 07/02/95 49755.658 66 15000 260

118623 05/05/95 49843.438 77 23000 400

07/02/95 49755.688 16 15000 470

NaID 08/05/95 49846.448 58 34000 450

10/02/95 49758.690 27 23000 420

125162 05/05/95 49843.490 40 23000 450

NaID 08/05/95 49846.484 23 34000 480

125489 06/05/95 49844.995 300 23000 370

NaID* 09/05/95 49847.983 187 34000 360

141851 06/05/95 49843.547 77 23000 260

NaID 08/05/95 49846.530 91 34000 480

153808 06/05/95 49843.584 22 23000 380

NaID 09/05/95 49846.568 15 34000 450

159082 07/05/95 49845.089 225 23000 300

NaID 11/05/95 49848.564 103 34000 901

161868 06/05/95 49843.607 24 23000 310

NaID 09/05/95 49846.587 22 34000 530

196821 31/10/95 50022.297 111 14000 200

NaID 02/11/95 50024.305 120 21000 220

204965 30/10/95 50021.328 114 14000 300

210418 10/11/94 49667.253 24 23000 300

01/11/95 50023.277 26 14000 400

11/11/94 49668.266 51 25000 360

 

 

star line(s) date HJD-2400000 exposure resolution S/N

HD d/m/y time (min.)

214454 10/11/94 49667.290 64 23000 300

11/11/94 49668.307 54 25000 300

217782 31/10/95 50022.359 48 14000 380

NaID 03/11/95 50025.341 82 21000 450

220061 10/11/94 49667.357 102 23000 250

01/11/95 50023.310 55 14000 380

11/11/94 49668.349 51 25000 300

221756 01/11/95 50023.373 120 14000 400

NaID 02/11/95 50024.388 100 21000 520

225180 30/10/95 50021.407 98 14000 300

NaID 04/11/95 50026.354 300 21000 400 *...mean of two spectra (HJDs are averaged, and exposure times added).

2.2. Radial velocities of photospheric lines

As in Paper I, we have taken advantage of an excellent signal-to-noise ratio to determine the radial velocity of the main photospheric lines (, , , and CaII-K). It is recalled that two procedures were used to derive the radial velocity. Each line was measured twice: by parabolic fit from the bottom of the profile and by the gravity centre of its lower part, limited by a straight horizontal line. Table 3 (click here) gives these two measurements for each observed line. In this table, radial velocities are given to one decimal digit, for the following reason. The wavelength of the line's bottom is defined by the minimum of the parabola fitted on point in the line core, and its precision is given approximately by the formula:

obtained by a similar way as the formula given by Gerstenkorn et al. (1977). With a 0.1 Å step for grating and , we therefore obtain 10^-4 Å, which is lower than the error of the Th-Ar dispersion curve, 0.015 Å. For a of 4000 Å\ (Ca II), this represents, in RV of the parabolic fit, a precision of , thus justifying the 1-decimal digit of RVs in Table 3 (click here).

In general, the radial velocities of the hydrogen lines are in agreement, although they are sometimes different from those of CaII-K. In Paper I, we suggested that these differences may be explained either by the different velocities of the hydrogen winds and of ionised calcium (stratification of the elements) or by the presence of a binary system whose spectral components vary in phase opposition, the hottest component showing H-lines and the coolest Ca II-K line. In some cases our mean radial velocities show a marked difference with those given by Hoffleit & Jaschek (1982). We will revert to these points in Sect. 5.

 

HD 11503 parabolic fit +8.4 +17.3 +12.0

RV = +4 V gravity centre +8.7 +16.8 +12.0

mean +8.6 +17.1 +12.0

HD 30739 parabolic fit +28.7

RV = +24 SB gravity centre +28.7

mean +28.7 mean of the 2 measurements = +28.7

HD 31295 parabolic fit +13.7

RV = +13 V gravity centre +13.5

mean +13.6 mean of the 2 measurements = +13.6

HD 34787 parabolic fit +8.3 +10.1 +8.7

RV = +12 SB gravity centre +8.1 +14.5 +9.0

mean +8.2 +12.3 +8.9

HD 38545 parabolic fit +11.5 +11.0 +12.1

RV = +21 V gravity centre +11.4 +12.6 +12.9

mean +11.5 +11.8 +12.5

HD 210418 parabolic fit -8.9 -6.7 -9.7

RV = -6 SB2 gravity centre -8.4 -10.1 -10.1

mean -8.7 -8.4 -9.9

HD 214454 parabolic fit +11.2 +9.2 +10.5

RV = +12 SB gravity centre +11.3 +9.1 +11.2

mean +11.2 +9.1 +10.8

HD 220061 parabolic fit +0.8 +9.2 +3.9

RV = +16 V gravity centre +2.1 +8.6 +3.4

mean +1.5 +8.9 +3.7 2) FEBRUARY 1995

HD 10411 parabolic fit -9.2 -7.7 -8.2

RV = +2 SB gravity centre -9.2 -8.4 -8.8

mean -9.2 -8.1 -8.5

HD 111604 parabolic fit -12.2

RV =-14 V gravity centre -17.6

mean -14.9 mean of the 2 measurements = -14.9

HD 112097 parabolic fit -7.5

RV = -l0 SB gravity centre -7.9

mean -7.7 mean of the 2 measurements= -7.7

HD 118623 parabolic fit -7.1 -4.3

RV = -6 V gravity centre -7.2 -5.3

mean -7.2 -4.8 3) MAY 1995 CaIIK

HD 108283 parabolic fit -21.5 2.3

RV = -4 SB gravity centre -22.3 2.7

mean -21.9 2.5

HD 110411 parabolic fit -9.4 -6.8

RV = +2 SB gravity centre -9.8 -6.9

mean -9.6 -6.8

 

 

HD 111604 parabolic fit -22.1 -10.2

RV = -14 V gravity centre -22.4 -9.7

mean -22.3 -10.0

HD 118623 parabolic fit -16.5 -8.9

RV = -6 V gravity centre -16.7 -9.0

mean -16.6 -9.0

HD 125162 parabolic fit -9.1 -8.9

RV = -8 gravity centre -9.5 -8.2

mean -9.3 -8.6

HD 125489 parabolic fit -30.1 -21.9

RV = -22 V gravity centre -30.7 -22.3

mean -30.4 -22.1

HD 141851 parabolic fit -18.7 -13.3

RV = -8 V gravity centre -18.2 -10.2

mean -18.5 -11.8

HD153808 parabolic fit -27.1 -29.3

RV = -25SBO gravity centre -27.4 -29.1

mean -27.2 -29.2

HD 159082 parabolic fit -59.8 -57.7

RV = -12 SBO gravity centre -58.7 -58.5

mean -59.2 -58.1

HD 161868 parabolic fit -20.5 -20.2

RV = -7 SB gravity centre -20.4 -19.9

mean -20.5 -20.0 4) OCTOBER-NOVEMBER 1995 CaIIK

HD 2904 parabolic fit -23.2 -3.9

RV = -10 gravity centre -25.6 -4.3

mean -24.4 -4.1

HD 5789 parabolic fit 1.1 16.8

RV = +l SB gravity centre 0.8 17.2

mean 0.9 17.0

HD 16811 parabolic fit -1.3 5.3

RV = -7 V gravity centre -1.1 6.1

mean -1.2 5.7

HD 23258 parabolic fit 14.5 16.4

RV = +15 SB gravity centre 14.6 16.4

mean 14.6 16.4

HD 34787 parabolic fit 9.2 10.2

RV = +12 SB gravity centre 8.7 13.3

mean 9.0 11.8

HD 36496 parabolic fit -24.8 -13.2

RV = -15 V? gravity centre -25.1 -13.3

mean -25.0 -13.2

HD 39283 parabolic fit -19.1 -17.1 -17.4

RV = -12 V? gravity centre -18.9 -17.2 -17.4

mean -19.0 -17.2 -17.4

 

HD 47152 parabolic fit 14.5 11.7

RV = +18 V? gravity centre 14.6 11.8

mean 14.5 11.8

HD 196821 parabolic fit -31.8 -24.5

RV = -37 SB? gravity centre -31.8 -24.2

mean -31.8 -24.4

HD 204965 parabolic fit -16.1 -14.4

RV = -17 SB gravity centre -16.7 -14.8

mean -16.4 -14.6

HD 210418 parabolic fit -9.1 -5.4

RV = -6 SB2 gravity centre -8.9 -4.8

mean -9.0 -5.1

HD 217782 parabolic fit -3.4 3.2

RV = +2 SB gravity centre -4.2 2.6

mean -3.8 2.9

HD 220061 parabolic fit 2.7 9.5

RV = +16 V gravity centre 3.4 9.3

mean 3.1 9.4

HD 221756 parabolic fit 12.9 14.2

RV = +13 V gravity centre 13.2 14.5

mean 13.0 14.3

HD 225180 parabolic fit -21.9 -14.0

RV = - 18 V gravity centre -22.2 -14.7

mean -22.0 -14.4

2.3. Radial velocities of shell lines

All the line profiles were examined carefully to detect a CS component. In addition to HD 16955 and HD 204965, already discussed in Paper I, we found eight more stars with such a component. Figure 1 (click here) shows the profile of the CaII-K line for these stars. It may be noted that no clearly pronounced CS component was found for HD 39283, while Andrillat et al. (1995) consider this star as LB shell. The radial velocity and the equivalent width of the CS component were then determined. Table 4 (click here) gives for each star these two quantities.

We obtained a spectrum of the CaII-K line of the Bootis prototype star (HD 125162), which deserves special mention. Barring errors on our part, no CaII-K line profiles of HD 125162 have been published up to the present.

Figure 2 (click here) shows this line, between and , for Boo and HD 31295 ( Ori), which has the same spectral type (A0V) and the same projected rotation velocity . The equivalent CaII-K widths are respectively:



Figure 3 (click here) shows an enlargement of the Boo CaII-K line illustrated in Fig. 2 (click here).

  
Figure 1: a) CaII-K line profile for HD 2904

 
Figure 1: b) As Fig. 1a for HD 5789

 
Figure 1: c) As Fig. 1a for HD 16811

 
Figure 1: d) As Fig. 1a for HD 34787 11/11/94

 
Figure 1: e) As Fig. 1a for HD 34787 2/11/95

 
Figure 1: f) As Fig. 1a for HD 38545

 
Figure 1: g) As Fig. 1a for HD 141851

 
Figure 1: h) As Fig. 1a for HD 161868

 
Figure 1: i) As Fig. 1a for HD 217782

  
Figure 2: Comparison of the spectrum of Boo (upper spectrum) and Ori mear CaII-K

  
Figure 3: CaII-K line profile of Boo

Contrary to what one would expect, this star has no circumstellar component in fine absorption, but what would appear to be two slight components in emission. It will be seen that at the bottom of the CaII-K line of Boo two weak emissions that are well separated from each other appear above the photospheric profile. They may be compared with what appears on the line of the Be star HD 47054 in Ballereau et al. 1995 (p. 440). However, this emission was only observed on one profile and has to be confirmed by further observations.

 

star HD date r/r*

2904 01/11/95 -2.7 13.2 13.35 6.6

5789 31/10/95 -4.1 14.1 16.3 5.8

16811 30/10/95 8.1 19.7 15.0 4.8

16955⁽¹⁾ 20/09/93 2.9 9.6 7.1 8.0

34787 11/11/94 5.2 18.1 8.0 8.5

34787 02/11/95 5.4 16.0 12.15 6.5

38545 11/11/94 11.1 72.2 9.9 6.8

141851 06/05/95 -27.5 2.3 6.9 9.0

161868 06/05/95 -30.3 6.0 8.95 7.5

204965⁽²⁾ 20/09/93 -18.2 8.1 6.9 5.3

217782 31/10/95 -9.8 20.0 13.75 5.9 component has vanished on a spectrum dated 30/10/95. continuum r/r* = Extension of the circumstellar disk, in stellar radii (see text).

Table 4: Some data from the circumstellar component of CaII K