1997A&AS..126..407P


Query : 1997A&AS..126..407P

1997A&AS..126..407P - Astron. Astrophys., Suppl. Ser., 126, 407-411 (1997/December-2)

A spectroscopic survey for λBootis stars. I. Strategy, techniques and first results.

PAUNZEN E. and GRAY R.O.

Abstract (from CDS):

In recent years, the chemically peculiar (CP) stars of the upper main sequence have become a fruitful field for the testing of astrophysical theories. Processes such as diffusion, convection and mass loss have been developed theoretically and introduced into models. The group of λ Bootis stars, however, is remarkable among the chemically peculiar stars as they are nonmagnetic, PopulationI, A to F-type dwarfs which show significant underabundances of metals (except for C, N, O and S). Unfortunately, the small number of confirmed members of the λ Bootis class makes a sound statistical analysis of their properties impossible. Thus, it is still difficult to decide between the two theories - mass loss with diffusion and the accretion theory - which have been proposed to explain the origin of these stars. We therefore have started a spectroscopic survey to find new λ Bootis stars in the field as well as in open clusters and associations. The presence of λ Bootis stars in open clusters and associations would permit a determination of the ages of these stars, and thus would yield an important test for distinguishing between the two theories. In this paper we describe the selection of candidates using photometric criteria, the basic requirements, spectroscopic follow-up observations and results from the first three observing runs. Special care was taken to avoid misclassification of our programme stars (e.g. λ Bootis stars are often confused with intermediate PopulationII, He-weak or high vsini stars), using a refined MK system. The discovery of at least six new λ Bootis stars (including three in the Orion OB1 association) shows the efficacy of our selection criteria.

Abstract Copyright:

Journal keyword(s): surveys - stars - λ Bootis - stars: chemically peculiar - stars: early type - stars: fundamental parameters

Simbad objects: 27

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Number of rows : 27
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 HD 23258 * 03 44 28.2037966608 +20 55 43.448620908   6.100 6.074     A0Vp_lB 57 0
2 HD 23392 * 03 44 32.7248403456 -08 35 12.466693284   8.29 8.24     A0Va-_lB 29 0
3 HD 290492 ** 05 31 18.76416 -00 29 24.1404   9.648 9.625 9.878   A0 24 0
4 HD 36726 * 05 33 51.7278163992 -00 04 36.342051096   8.91 8.82     hA5VkA0mA0_lB 40 1
5 HD 294253 HS* 05 36 41.7835166016 -03 30 12.476798712   9.675 9.637 9.974   A0VakB8.5mB9(_lB) 36 1
6 NAME Ori I As* 05 38 -02.8           ~ 616 0
7 HD 39421 * 05 52 07.7290666608 -09 02 30.844893552   6.045 5.960     A0V 59 0
8 NGC 2232 OpC 06 27 33.1 -04 44 56           ~ 188 0
9 HD 261809 * 06 40 43.2963115584 +10 08 30.557120604   11.2 10.8     A0/1 18 0
10 NGC 2264 OpC 06 40 52.1 +09 52 37           ~ 1799 0
11 HD 261904 Y*O 06 41 00.6874797312 +09 24 11.888973612   10.38 9.50     A0/1 38 0
12 NGC 2301 OpC 06 51 46.3 +00 27 54   6.30 6.0     ~ 159 0
13 V* DD Lyn dS* 07 55 40.8273346368 +35 24 45.653471280   6.478 6.221     A3p 74 0
14 HD 66684 ** 08 05 37.05577 +27 31 47.0419   6.22 6.21     B9.5Vp_lB+A0Vnp 45 0
15 * 50 Cnc PM* 08 46 56.0189914848 +12 06 35.830080180   5.992 5.885 7.20 5.76 A1Vp 92 0
16 HD 74911 * 08 47 10.1616904416 +09 23 00.712309380   8.64 8.51     A5 18 0
17 HD 84123 PM* 09 44 06.8766339648 +42 03 03.128528304   7.135 6.838     A4III 55 0
18 HD 84948 SB* 09 50 05.8773671472 +49 04 31.750535568   8.42 8.12     F0 57 0
19 HD 90821 * 10 29 37.0986897144 +26 10 58.569963240   9.54 9.45     F0 19 0
20 * 33 LMi * 10 31 51.3753968952 +32 22 46.405276428   6.001 5.905     A0Va- 70 0
21 HD 101108 * 11 38 19.3666459704 +38 45 16.889006304   9.05 8.87     A5_lB 43 0
22 HD 105058 dS* 12 05 43.3556676096 +49 40 55.994662056   9.05 8.88     A2p 64 0
23 HD 105199 Pe* 12 06 47.0204384616 +30 15 41.874380208   9.97 9.83     A0IVSr 38 0
24 V* FQ Boo dS* 13 49 44.1554383104 +08 24 31.089742272   6.717 6.604     hA5VkA2mA2_lB 48 0
25 HD 149303 * 16 31 47.2275879216 +45 35 53.744910612 5.850 5.78 5.68 7.16   A2Vn_lB 64 0
26 HD 170680 * 18 31 26.2978449720 -18 24 09.713977668   5.126 5.117     B9/9.5V 84 0
27 HD 171948 SB* 18 36 37.0229804112 +22 06 27.294803964   6.82 6.77     B9 38 1

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