J/AJ/155/91 Be stars in open clusters with PTF/iPTF. I. (Yu+, 2018)
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 2018AJ....155...91Y (SIMBAD/NED BibCode)
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
Hα 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 2009PASP..121.1395L) and intermediate PTF (iPTF;
Kulkarni 2013ATel.4807....1K 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 Hα 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 2015AJ....149...43Y, 2016AJ....151..121Y 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°<l<240°; (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
--------------------------------------------------------------------------------
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 χ 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
--------------------------------------------------------------------------------
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
µαcosδ
48- 52 F5.2 mas/yr pmDE [-8.86/2.93] Proper motion of DE µδ
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 2008JPhCS.118a2078Z);
b = Morgan et al. (1955ApJS....2...41M 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 1976ApJ...204..493S);
f = Mathew et al. (2008MNRAS.388.1879M 2008MNRAS.388.1879M);
g = Barbon & Hassan (1973A&AS...10....1B 1973A&AS...10....1B);
h = Souza et al. (2016AAS...22831903S);
i = Kubat et al. (2007A&A...472..163K 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
--------------------------------------------------------------------------------
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
µαcosδ
52- 55 F4.1 mas/yr pmDE [-9.1/10.3] Proper motion of DE µδ
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-Ks) 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
--------------------------------------------------------------------------------
1- 19 A19 --- Star Name of Be star candidate
21- 26 F6.3 mag W1mag [9.174/13.081] WISE W1 (3.4µm) 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 (4.6µm) 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 (12µm) 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
(End) Tiphaine Pouvreau [CDS] 22-Oct-2018