J/AJ/156/61 A study of the Hα variability of Be stars (Dimitrov+, 2018)
A study of the Hα variability of Be stars.
Dimitrov D.P., Kjurkchieva D.P., Ivanov E.I.
<Astron. J., 156, 61 (2018)>
=2018AJ....156...61D 2018AJ....156...61D (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Associations, stellar ; Photometry, infrared ;
Stars, Be ; Spectral types ; Radial velocities ; Proper motions ;
Photometry, H-alpha ; Equivalent widths ; Stars, distances
Keywords: line: profiles - open clusters and associations: general -
stars: early-type - stars: emission-line, Be
Abstract:
This paper presents the results of 4 years of high-resolution spectral
observations of 69 emission-line stars, 54 of them being newly discovered
sources. We classified the stars on the basis of their position in the
two-color IR diagram and some additional criteria: shape and width of
the Hα profile, presence of He lines, proper motion and parallax,
membership to open cluster and associations. Sixty of our targets turned
out to be Be stars. We also found four late giants, four pre-MS stars,
and one late dwarf. The Hα emission profiles of our Be stars range
from single peaked to typical shell profiles that can also be highly
asymmetric or single-peaked profiles with a narrow absorption core.
The emission profiles appear almost constant with time or highly variable
in intensity and in their V/R ratio. The detected long-term variability of
the Hα emission is important for investigating the on/off switch
phenomenon of Be stars. Our study led to an increase of the number of
the emission-line stars of 16 open clusters.
Description:
We observed nearly 100 fields centered on the galactic equator (galactic
latitude range [-10°, +10°]) using the 60 cm telescope of the
Rozhen National Astronomical Observatory and found several thousands
emission candidates (Dimitrov & Kyurkchieva 2012BlgAJ..18c..63D 2012BlgAJ..18c..63D). The
line-emission nature of about 150 of them was confirmed by low-resolution
spectral observations with the 2 m telescope of the Rozhen National
Astronomical Observatory equipped with focal reducer FoReRo2 and grism
with 300 grooves/mm (Dimitrov & Kyurkchieva 2012BlgAJ..18c..63D 2012BlgAJ..18c..63D). We have
recently carried out high-resolution Coude spectral observations of 69
targets brighter than 13.5 V mag, and the paper presents the results
of this study.
The spectral observations were carried out from the end of 2011 to the
end of 2014 (Table 2). We used a CCD camera Photometrics AT200 with
the SITe SI003AB 1024x1024 pixels chip mounted on the Coude spectrograph
(grating B&L632/14.7°) of the 2 m telescope of the National
Astronomical Observatory at Rozhen (Bulgaria). The resolution of the
spectra is 0.19 Å/pixel (R∼16000).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 93 69 Available information about the targets
table2.dat 91 341 Log of observations and parameters of
the Hα emission
table4.dat 134 10 Astrometric parameters of targets suspected
as members of open stellar clusters
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See also:
V/125 : Photometry and Spectroscopy for Luminous Stars (Reed 2005)
I/317 : The PPMXL Catalog (Roeser+ 2010)
I/322 : UCAC4 Catalogue (Zacharias+, 2012)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJ/454/151 : OB Associations of the Northern Milky Way (Massey+ 1995)
J/other/RMxAA/33.83 : NGC 129 positions and proper motions (Stock+ 1997)
J/A+A/376/144 : BV(RI)CHα photometry of NGC 663 (Pigulski+, 2001)
J/AJ/124/2254 : Speckle interferometry at USNO. VIII. (Mason+, 2002)
J/AN/325/740 : Astrophysical supplements to ASCC-2.5 (Kharchenko+, 2004)
J/ApJS/161/118 : byHα photometry in open clusters (McSwain+, 2005)
J/A+A/446/785 : Catalogue of eclipsing variables (Malkov+, 2006)
J/ApJ/652/458 : BVRHα photometry of candidates Be stars
(Wisniewski+, 2006)
J/AJ/136/2413 : Galactic midplane Spitzer red sources (Robitaille+, 2008)
J/ApJ/700/1216 : Spectroscopy of Be stars in open clusters
(McSwain+, 2009)
J/A+A/515/A16 : UBVI light curves of NGC 884 variables (Saesen+, 2010)
J/ApJS/187/228 : Hα profiles of Be stars (Silaj+, 2010)
J/MNRAS/403/1491 : Integrated magnitudes of synthetic star clusters
(Pandey+ 2010)
J/ApJ/726/19 : Intermediate-mass stars in IC 1805 (Wolff+, 2011)
J/other/BASI/39.517 : Spectroscopy of classical Be stars (Mathew+, 2011)
J/A+A/550/A79 : Hα and Hβ lines of northern Be stars
(Catanzaro, 2013)
J/A+A/564/A79 : Proper motions of open clusters from UCAC4 (Dias+, 2014)
J/MNRAS/444/290 : Star clusters distances and extinctions. II.
(Buckner+, 2014)
J/A+A/591/A140 : IPHAS-selected classical Be stars (Gkouvelis+, 2016)
J/MNRAS/463/1162 : Infrared photometry of Be stars (Chen+, 2016)
J/AJ/153/174 : SDSS-III/APOGEE. II. The multi-epoch ABE sample
(Chojnowski+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Target name (JHHMM+DDHH)
12- 13 I2 h RAh Hour of Right Ascension (J2000)
15- 16 I2 min RAm Minute of Right Ascension (J2000)
18- 23 F6.3 s RAs Second of Right Ascension (J2000)
25 A1 --- DE- Sign of the Declination (J2000)
26- 27 I2 deg DEd Degree of Declination (J2000)
29- 30 I2 arcmin DEm Arcminute of Declination (J2000)
32- 36 F5.2 arcsec DEs Arcsecond of Declination (J2000)
38- 43 F6.3 mag Jmag [7.456/13.33]? 2MASS J band magnitude
45- 50 F6.3 mag J-H [-0.131/0.923]? 2MASS (J-H) color
52- 56 F5.3 mag H-Ks [0.025/1.656]? 2MASS (H-Ks) color
58- 71 A14 --- SpType Spectral type as given in SIMBAD
73- 87 A15 --- Cluster Cluster membership
89- 93 A5 --- Ref Reference codes (1)
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Note (1): Reference code as follows:
1 = Turner et al. (1992AJ....104.1132T 1992AJ....104.1132T);
2 = Chojnowski et al. (2017, J/AJ/153/174);
3 = Stock & Stock (1997, J/other/RMxAA/33.83);
4 = Reed (2003, Cat. V/125);
5 = Gaia Collaboration et al. (2016, Cat. I/337);
6 = Kharchenko et al. (2004, J/AN/325/740);
7 = Malkov et al. (2006, J/A+A/446/785);
8 = Mathew & Subramaniam (2011, J/other/BASI/39.517);
9 = Farnsworth (1955ApJS....2..123F 1955ApJS....2..123F);
10 = Pigulski et al. (2001, J/A+A/376/144);
11 = Bragg & Kenyon (2002AJ....124.3289B 2002AJ....124.3289B);
12 = Saesen et al. (2010, J/A+A/515/A16);
13 = Wolff et al. (2011, J/ApJ/726/19);
14 = Imai et al. (2017ApJ...845...99I 2017ApJ...845...99I);
15 = Robitaille et al. (2008, J/AJ/136/2413);
16 = Hojaev (2005JApA...26..293H 2005JApA...26..293H);
17 = Mason et al. (2002, J/AJ/124/2254);
18 = Arzoumanian et al. (2004ApJ...610L.101A 2004ApJ...610L.101A);
19 = Arzoumanian et al. (2008ApJ...687..505A 2008ApJ...687..505A);
20 = Jerzykiewicz et al. (1996AcA....46..253J 1996AcA....46..253J);
21 = Massey et al. (1995, J/ApJ/454/151);
22 = Usatov & Nosulchik (2008OEJV...87....1U 2008OEJV...87....1U).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Target name (JHHMM+DDHH)
12- 22 A11 "date" Date Date of observation
24- 27 I4 s Exp [120/3600] Exposure time
29- 34 F6.2 --- S/N [1.42/107] Signal-to-noise ratio
36- 41 F6.1 km/s RV-V [-354.5/-53]? Radial velocity of the left (V) peak
43- 48 F6.1 km/s RV-C [-282.3/35.8]? Radial velocity of the center (C)
50- 54 F5.1 km/s RV-R [-51.9/296.8]? Radial velocity of the right (R)
peak
56- 60 F5.2 --- I-V [0.98/10.54]? Normalized intensity of the left (V)
peak
62- 66 F5.2 --- I-C [0.08/11.95]? Normalized intensity of the center
(C)
68- 72 F5.2 --- I-R [0.95/10.92]? Normalized intensity of the right
(R) peak
74- 78 F5.1 km/s FWHM [67.4/733.7]? FWHM of the Hα profile
80- 84 F5.2 0.1nm EW [-3.97/58.31]? EW of the Hα emission (Å)
86- 91 A6 --- HeI Presence/lack of He I 6678 line in our spectra?
(1)
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Note (1): J2226+4644 seems to be an early M giant (probably M4III).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Target name (JHHMM+DDHH)
12- 22 A11 --- Cluster Cluster name
24- 26 F3.1 arcmin Size [3/9.8] Cluster size
28- 33 F6.3 mas/yr pmRA1 [-3.923/-0.569] Cluster proper motion in RA
35- 39 F5.3 mas/yr e_pmRA1 [0.061/0.17] Uncertainty in pmRA1
41- 46 F6.3 mas/yr pmDE1 [-5.45/-0.093] Cluster proper motion in DE
48- 52 F5.3 mas/yr e_pmDE1 [0.076/0.23] Uncertainty in pmDE1
54- 59 F6.2 km/s RV1 [-58.3/-6.8]? Cluster radial velocity
61- 64 F4.2 km/s e_RV1 [1.4/2.6]? Uncertainty in RV1
66- 69 F4.2 kpc Dist1 [1.8/3.68] Cluster distance
71- 74 F4.2 kpc e_Dist1 [0.17/0.52] Uncertainty in Dist1
76 A1 --- l_Dist [<] Limit flag on Dist
77- 80 F4.1 arcmin Dist [1/11.2] Target distance from the cluster
center
82- 87 F6.3 mas/yr pmRA2 [-4.911/-0.596] Target proper motion in RA
89- 93 F5.3 mas/yr e_pmRA2 [0.022/0.325] Uncertainty in pmRA2
95-100 F6.3 mas/yr pmDE2 [-5.948/-0.425] Target proper motion in DE
102-106 F5.3 mas/yr e_pmDE2 [0.024/0.359] Uncertainty in pmDE2
108-112 F5.1 km/s RV2 [-71/64.7] Target radial velocity determined
by our spectra
114 A1 --- l_Dist2 [>] Limit flag on Dist2
115-119 F5.2 kpc Dist2 [0.9/10] Target distance
121-124 F4.2 kpc e_Dist2 [0.05/0.67]? Uncertainty in Dist2
126 A1 --- Mem Estimated membership (1)
128-134 A7 --- Ref References (2)
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Note (1): Membership code as follows:
Y = Member;
P = Possible member;
N = Nonmember.
Note (2): Reference as follows:
1 = Dias et al. (2014, J/A+A/564/A79);
2 = Buckner & Froebrich (2014, J/MNRAS/444/290);
3 = Zacharias et al. (2013, Cat. I/322);
4 = Roeser et al. (2010, Cat. I/317);
5 = Gaia Collaboration et al. (2016, Cat. I/337; 2018, Cat. I/345);
6 = Pandey et al. (2010, J/MNRAS/403/1491).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 29-Jan-2019