J/AJ/155/91       Be stars in open clusters with PTF/iPTF. I.        (Yu+, 2018)
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Searching for Be stars in the open clusters with PTF/iPTF.
I. Cluster sample and Be star candidates.
    Yu P.-C., Yu C.-H., Lee C.-D., Lin C.-C., Hsia C.-H., Chang C.-K.,
    Chen I.-C., Ngeow C.-C., Ip W.-H., Chen W.-P., Laher R., Surace J.,
    Kulkarni S.R.
   <Astron. J., 155, 91-91 (2018)>
   =2018AJ....155...91Y    (SIMBAD/NED BibCode)
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ADC_Keywords: Clusters, open ; Stars, Be ; Proper motions ; Photometry, infrared
Keywords: open clusters and associations: general - stars: emission-line, Be -
          stars: general - surveys

Abstract:
    We conducted a search for Be star candidates in open clusters using
    H{alpha} imaging photometry of the Palomar Transient Factory Survey to
    investigate some connections among Be star phenomena, cluster environments,
    and ages. Stellar members of clusters were identified by spatial
    distributions, near-infrared magnitudes and colors, and by proper motions.
    Among 104 open clusters, we identified 96 Be star candidates in 32
    clusters; 11 of our candidates have been reported in previous studies.
    We found that the clusters with age 7.5<log(t(year))=<8.5 tend to have
    more Be star candidates; there is about a 40% occurrence rate within
    this age bin. The clusters in this age bin also tend to have a higher
    Be fraction N(Be)/N(Be+B-type). These results suggest that the environments
    of young and intermediate clusters are favorable to the formation of
    Be phenomena. Spatial distribution of Be star candidates with different
    ages implies that they do not form preferentially in the central regions.
    Furthermore, we showed that the mid-infrared (MIR) colors of the Be star
    candidates are similar to known Be stars, which could be caused by
    free-free emission or bound-free emission. Some Be star candidates might
    have no circumstellar dust according to their MIR colors. Finally, among
    96 Be candidates, we discovered that one Be star candidate FSR 0904-1
    exhibits long-term variability on the timescale of ~2000 days with an
    amplitude of 0.2-0.3 mag, indicating a long timescale of disk evolution.

Description:
      Modern surveys with wide field cameras, such as the Palomar Transient
    Factory (PTF; Law et al. 2009PASP..121.1395L) and intermediate PTF (iPTF;
    Kulkarni 2013ATel.4807....1K; https://www.ptf.caltech.edu/iptf), benefit
    not only from time saving in a comprehensive survey, but also the coverage
    of an entire cluster occupying a wide sky area. The data of PTF/iPTF
    were taken by the 48 inch Samuel Oschin Telescope located at Palomar
    Observatory, using an 11-CCD-mosaic camera with a 7.3 square-degree field
    of view. The wide field of the PTF/iPTF H{alpha} images allow us to
    conduct a program to search for Be star candidates in open clusters of
    different ages (Yu et al. 2015AJ....149...43Y, 2016AJ....151..121Y).
      We selected 104 clusters from Kharchenko et al. (2013, J/A+A/558/A53)
    on the basis of following criteria: (1) to study the connection between
    Be star and ages, we have selected cluster ages with 6.5<log(t(year))=<10;
    (2) to avoid difficulties of membership identification near the Galactic
    center, we have selected clusters located at Galactic-longitude range
    30{deg}<l<240{deg}; (3) to avoid too many bright, and to extend the sample
    of faint, Be stars, we constrained cluster distance from the Sun within
    1 kpc<D<2.5 kpc.

File Summary:
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 FileName      Lrecl  Records   Explanations
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ReadMe            80        .   This file
table1.dat        91      104   Basic Properties of the Cluster Sample
table2.dat        82       96   Basic Properties of Be Star Candidates
table3.dat        78       96   WISE Photometric Data of Be Candidates
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See also:
 II/313              : Palomar Transient Factory (PTF) photometric catalog 1.0
                                                                   (Ofek+, 2012)
 J/ApJ/700/1216      : Spectroscopy of Be stars in open clusters
                                                                (McSwain+, 2009)
 J/other/BASI/39.517 : Spectroscopy of classical Be stars (Mathew+, 2011)
 J/AJ/144/158        : Properties of B and Be stars in h and {chi} Persei
                                                                  (Marsh+, 2012)
 J/A+A/558/A53       : Milky Way global survey of star clusters. II.
                                                             (Kharchenko+, 2013)
 J/AJ/155/50         : WISE photometry of Be stars in young open clusters
                                                                (Granada+, 2018)
 http://www.ptf.caltech.edu/ : Palomar Transient Factory survey

Byte-by-byte Description of file: table1.dat
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   Bytes Format Units    Label   Explanations
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   1- 16  A16   ---      Cluster Name of cluster
  18- 19  I2    h        RAh     Hour of Right Ascension (J2000)
  21- 22  I2    min      RAm     Minute of Right Ascension (J2000)
  24- 28  F5.2  s        RAs     Second of Right Ascension (J2000)
      29  A1    ---      DE-     Sign of the Declination (J2000)
  30- 31  I2    deg      DEd     Degree of Declination (J2000)
  33- 34  I2    arcmin   DEm     Arcminute of Declination (J2000)
  36- 40  F5.2  arcsec   DEs     [0/60] Arcsecond of Declination (J2000)
  42- 46  F5.2  mas/yr   pmRA    [-6.78/4.47] Proper motion of RA
                                  {mu}_{alpha}_cos{delta}
  48- 52  F5.2  mas/yr   pmDE    [-8.86/2.93] Proper motion of DE {mu}_{delta}_
  54- 58  F5.3  kpc      Dist    [1/2.5] Distance of cluster to the Sun
  60- 63  F4.2  [yr]     logAge  [6.7/9.6] Logarithm of the cluster age
  65- 69  F5.3  [yr]   e_logAge  [0.01/0.203]? Uncertainty in logAge
  71- 74  F4.1  arcmin   Size    [2.6/57.1] Size of searching region
  76- 77  I2    ---      N(Be)   [0/14] Number of Be star candidate(s) found in
                                  this work
  79- 80  I2    ---      K(Be)1  [1/15]? First known Be star number from
                                  literature
      82  I1    ---      K(Be)2  [4]? Second known Be star number from
                                  literature
  84- 86  I3    ---      N       [0/515] Number of B-type star(s) in cluster
  88- 91  A4    ---    r_K(Be)   Reference(s) of known Be stars (1)
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Note (1): Reference as follows:
  a = Zhang et al. (2008JPhCS.118a2078Z);
  b = Morgan et al. (1955ApJS....2...41M);
  c = WEBDA: https://www.univie.ac.at/webda/;
  d = Marsh Boyer et al. (2012, J/AJ/144/158);
  e = Schild & Romanishin (1976ApJ...204..493S);
  f = Mathew et al. (2008MNRAS.388.1879M);
  g = Barbon & Hassan (1973A&AS...10....1B);
  h = Souza et al. (2016AAS...22831903S);
  i = Kubat et al. (2007A&A...472..163K);
  j = Mathew & Subramaniam (2011, J/other/BASI/39.517).
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Byte-by-byte Description of file: table2.dat
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   Bytes Format Units    Label  Explanations
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   1- 19  A19   ---      Star   Name of Be star candidate
      20  A1    ---    f_Star   [*] Flag on Star (1)
  22- 23  I2    h        RAh    Hour of Right Ascension (J2000)
  25- 26  I2    min      RAm    Minute of Right Ascension (J2000)
  28- 32  F5.2  s        RAs    Second of Right Ascension (J2000)
      33  A1    ---      DE-    Sign of the Declination (J2000)
  34- 35  I2    deg      DEd    Degree of Declination (J2000)
  37- 38  I2    arcmin   DEm    Arcminute of Declination (J2000)
  40- 44  F5.2  arcsec   DEs    Arcsecond of Declination (J2000)
  46- 50  F5.1  mas/yr   pmRA   [-10.1/7] Proper motion of RA
                                 {mu}_{alpha}_cos{delta}
  52- 55  F4.1  mas/yr   pmDE   [-9.1/10.3] Proper motion of DE {mu}_{delta}_
  57- 61  F5.3  mag      J-H    [0.016/0.344] 2MASS (J-H) color index
  63- 67  F5.3  mag      H-Ks   [0.029/0.331] 2MASS (H-K_s_) color index
  69- 74  F6.3  mag      Rmag   [11.01/15.15] R band magnitude obtained from
                                 USNO-B and PTF/iPTF catalogue
  76- 82  A7    ---      Class  Object classification adopted from SIMBAD (2)
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Note (1): Flag as follows:
  * = Object reported in WEBDA (https://www.univie.ac.at/webda/).
Note (2): Object classification as follows:
  Be = Be star;
  iC = Star in cluster;
  Em = Emission-line star.
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Byte-by-byte Description of file: table3.dat
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   Bytes Format Units   Label  Explanations
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   1- 19  A19   ---     Star   Name of Be star candidate
  21- 26  F6.3  mag     W1mag  [9.174/13.081] WISE W1 (3.4{mu}m) band magnitude
  28- 32  F5.3  mag   e_W1mag  [0.021/0.128] Uncertainty in W1mag
  34- 39  F6.3  mag     W2mag  [8.822/13.147] WISE W2 (4.6{mu}m) band magnitude
  41- 45  F5.3  mag   e_W2mag  [0.019/0.038] Uncertainty in W2mag
  47- 52  F6.3  mag     W3mag  [7.901/12.061]? WISE W3 (12{mu}m) band magnitude
  54- 58  F5.3  mag   e_W3mag  [0.018/0.267]? Uncertainty in W3mag
  60- 64  F5.3  [yr]    logAge [6.7/9.22] Logarithm of the host cluster age
  66- 71  F6.3  mag     W1-W2  [-0.134/0.405] WISE W1-W2 color index
  73- 78  F6.3  mag     W2-W3  [-0.524/1.791]? WISE W2-W3 color index
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History:
    From electronic version of the journal

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(End)                      Tiphaine Pouvreau [CDS]                   22-Oct-2018