Stars with low vsini 

Last update:  April 23, 2208
Author:  Jill Bechtold


The best check of focus and astigmatism is to observe a star with low rotational velocity (vsini) whose lines should be unresolved with MAESTRO, even with the smallest slits.  
The focus and astigmatism of a star will be different from what is observed in exposures of the calibration lamps, since the lamps illuminate the slit with a diffuse beam, whereas the starlight goes through the primary-secondary-corrector system and enters the spectrograph as an f/5 beam.  (The slit is beneath the "injection optics" and sees an f/3 beam).  Indeed, at the current writing (April 2008), users of the 0.3" slits will notice some defocus and  astigmatism in the blue part of the echelle format.  We hope to tilt the ccd slightly before the next run to alleviate these problems.  

The other type of object that is useful to oberve are stars with interesting ISM absorption, which have been observed at Coude resolution.

SIMBAD can be used to look for stars, but unfortunately the vsini information is not useful.  If you query the database you get a lot of stars with vsini = 0 which were observed in the late 60's with photographic plates.  Instead we suggest you use the stars observed for planet searches by the CORAVEL folks, e.g. de Medieros & Mayor 1999 A&A Suppl. 139, 433.  These measurements are not, unfortunately, included in the SIMBAD data base, as far as we can tell.

A list of these stars, with vsini, RA, Dec and propermotion listed, in rough RA order, is given here.  

NOTE that the units of proper motion are NOT what the MMT Catalog programs expect.  The easiest way to point at one of these stars is to go to the MMT catalog web page and input the star's HD or BD number as listed in the file, and the proper entry will come up in MMT Catalog format.  

A file in MMT catalog format for all the stars will be added to this web site soon.

Here is more information about the list of stars:
J/A+AS/139/433      RV and vsini of evolved stars          (de Medeiros+ 1999)
================================================================================
A catalog of rotational and radial velocities for evolved stars.
       de Medeiros J.R., Mayor M.
      <Astron. Astrophys. Suppl. Ser. 139, 433 (1999)>
      =1999A&AS..139..433D      (SIMBAD/NED BibCode)
================================================================================
ADC_Keywords: Stars, late-type ; Radial velocities ; Rotational velocities

Keywords: stars: rotation; late-type; kinematics -
          techniques: radial velocities - catalogs

Abstract:
    Rotational and radial velocities have been measured for about 2000
    evolved stars of luminosity classes IV, III, II and Ib covering the
    spectral region F, G and K. The survey was carried out with the
    CORAVEL spectrometer. The precision for the radial velocities is
    better than 0.30km/s, whereas for the rotational velocity measurements
    the uncertainties are typically 1.0km/s for subgiants and giants and
    2.0km/s for class II giants and Ib supergiants. These data will add
    constraints to studies of the rotational behaviour of evolved stars as
    well as solid informations concerning the presence of external
    rotational brakes, tidal interactions in evolved binary systems and on
    the link between rotation, chemical abundance and stellar activity.