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J/MNRAS/392/1456  VIc photometry of M50 (NGC 2323) low-mass stars (Irwin+, 2009)
The monitor project: rotation periods of low-mass stars in M50.
    Irwin J., Aigrain S., Bouvier J., Hebb L., Hodgkin S., Irwin M., Moraux E.
   <Mon. Not. R. Astron. Soc., 392, 1456-1466 (2009)>
   =2009MNRAS.392.1456I
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Photometry, CCD

Keywords: techniques: photometric - surveys - stars: pre-main-sequence -
          stars: rotation - open clusters and associations: individual: M50

Abstract:
    We report on the results of a time-series photometric survey of M50
    (NGC 2323), a ∼130Myr open cluster, carried out using the Cerro Tololo
    Inter-American Observatory (CTIO) 4-m Blanco telescope and Mosaic-II
    detector as part of the Monitor project. Rotation periods were derived
    for 812 candidate cluster members over the mass range
    0.2≤M/M☉≤1.1. The rotation period distributions show a clear
    mass-dependent morphology, statistically indistinguishable from those
    in NGC 2516 and M35 taken from the literature. Due to the availability
    of data from three observing runs separated by ∼10 and 1 month
    time-scales, we are able to demonstrate clear evidence for evolution
    of the photometric amplitudes, and hence spot patterns, over the 10
    month gap. We are not able to constrain the time-scales for these
    effects in detail due to limitations imposed by the large gaps in our
    sampling, which also prevent the use of the phase information.

Description:
    Photometric monitoring observations were obtained as part of the
    Monitor project, using the 4-m Blanco telescope at Cerro Tololo
    Inter-American Observatory (CTIO), with the Mosaic-II imager. A total
    of ∼95h of photometric monitoring was conducted, spread over three
    distinct observing runs: 6xfull-nights in two three-night segments
    spanning 2005 February 04-06 and 2005 February 14-16, 8x1/2 nights
    between 2005 December 24 and 2006 January 06 and 4xfull-nights between
    2006 January 28 and 2006 February 01. M50 was observed in a single
    telescope pointing centred on the cluster, for ∼8h per night 
    (∼4h per 1/2 night).

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat       119      812   Properties of our 812 rotation candidates


See also:
  J/A+AS/128/131 : UBV photometry of NGC 2323 (Claria+ 1998)


Byte-by-byte Description of file: table1.dat

   Bytes Format Units   Label      Explanations

   1- 11  A11   ---     [IAB2009]  Identifier (M50-N-NNNN) (1)
  12- 13  I2    h       RAh        Right ascension (J2000)
  15- 16  I2    min     RAm        Right ascension (J2000)
  18- 22  F5.2  s       RAs        Right ascension (J2000)
      24  A1    ---     DE-        Declination sign (J2000)
  25- 26  I2    deg     DEd        Declination (J2000)
  28- 29  I2    arcmin  DEm        Declination (J2000)
  31- 34  F4.1  arcsec  DEs        [0/60] Declination (J2000)
  36- 41  F6.3  mag     Vmag       Johnson V magnitude
  43- 47  F5.3  mag     e_Vmag     rms uncertainty on Vmag
  49- 54  F6.3  mag     Icmag      Cousins I magnitude
  56- 60  F5.3  mag     e_Icmag    rms uncertainty on Imag
  62- 67  F6.3  d       Per        Period
  69- 74  F6.4  mag     a1mag      i-band instrumental α1 amplitude
  76- 81  F6.4  mag     e_a1mag    rms uncertainty on a1mag
  83- 88  F6.4  mag     a2mag      i-band instrumental α2 amplitude
  90- 95  F6.4  mag     e_a2mag    rms uncertainty on a2mag
  97-102  F6.4  mag     a3mag      i-band instrumental α3 amplitude
 104-109  F6.4  mag     e_a3mag    rms uncertainty on a3mag
 111-114  F4.2  solMass Mass       Interpolated Mass (2)
 116-119  F4.2  solRad  Rad        Interpolated Radius (2)

Note (1): Our identifiers are formed using a simple scheme of the cluster
     name, CCD number and a running count of stars in each CCD,
     concatenated with dashes.
Note (2): From the models of Baraffe et al. (1998, Cat. J/A+A/337/403),
     derived using the I magnitudes.


History:
    From electronic version of the journal
(End)                                      Patricia Vannier [CDS]    18-Aug-2009