2014A&A...563A..86L


C.D.S. - SIMBAD4 rel 1.7 - 2020.03.28CET16:54:56

2014A&A...563A..86L - Astronomy and Astrophysics, volume 563A, 86-86 (2014/3-1)

Determination of the position angle of stellar spin axes.

LESAGE A.-L. and WIEDEMANN G.

Abstract (from CDS):

Measuring the stellar position angle provides valuable information on binary stellar formation or stellar spin axis evolution. We aim to develop a method for determining the absolute stellar position angle using spectro-astrometric analysis of high resolution long-slit spectra. The method has been designed in particular for slowly rotating stars. We investigate its applicability to existing dispersive long-slit spectrographs, identified here by their plate scale, and the size of the resulting stellar sample. The stellar rotation induces a tilt in the stellar lines whose angle depends on the stellar position angle and the orientation of the slit. We developed a rotation model to calculate and reproduce the effects of stellar rotation on unreduced high resolution stellar spectra. Then we retrieved the tilt amplitude using a spectro-astrometric extraction of the position of the photocentre of the spectrum. Finally we present two methods for analysing the position spectrum using either direct measurement of the tilt or a cross-correlation analysis. For stars with large apparent diameter and using a spectrograph with a small plate scale, we show that it is possible to determine the stellar position angle directly within 10° with a signal-to-noise ratio of the order of 6. Under less favourable conditions, i.e. larger plate scale or smaller stellar diameter, the cross-correlation method yields comparable results. We show that with the currently existing instruments, it is possible to determine the stellar position angle of at least 50 stars precisely, mostly K-type giants with apparent diameter down to 5 milliarcseconds. If we consider errors of around 10° still acceptable, we may include stars with apparent diameter down to 2mas in the sample that then comprises also some main sequence stars.

Abstract Copyright:

Journal keyword(s): stars: rotation - techniques: spectroscopic

Status at CDS:  

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 * alf Tau LP? 04 35 55.23907 +16 30 33.4885 4.32 2.40 0.86 -0.37 -1.31 K5+III 1177 1
2 * alf Ori s*r 05 55 10.30536 +07 24 25.4304 4.38 2.27 0.42 -1.17 -2.45 M1-M2Ia-Iab 1456 0
3 V* RS Vir Mi* 14 27 16.3931666073 +04 40 41.085779853   10.27 7.00     M8 197 0
4 V* TW Oph C* 17 29 43.6641693394 -19 28 22.867073875   12.95 8.79 7.54 8.70 C-N5 107 0
5 * alf Lyr dS* 18 36 56.33635 +38 47 01.2802 0.03 0.03 0.03 0.07 0.10 A0Va 2488 0
6 * alf Aql dS* 19 50 46.99855 +08 52 05.9563 1.07 0.98 0.76 0.62 0.49 A7Vn 813 0

    Equat.    Gal    SGal    Ecl

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2020.03.28-16:54:56

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