J/MNRAS/443/2492 Δa observations of 3 globular clusters (Paunzen+, 2014)
The first Δa observations of three globular clusters.
Paunzen E., Iliev I.KH., Pintado O.I., Baum H., Maitzen H.M., Netopil M.,
Onehag A., Zejda M., Fraga L.
<Mon. Not. R. Astron. Soc., 443, 2492-2498 (2014)>
=2014MNRAS.443.2492P 2014MNRAS.443.2492P
ADC_Keywords: Clusters, globular ; Photometry
Keywords: techniques: photometric - stars: chemically peculiar -
stars: horizontal branch - globular clusters: individual: NGC 104 -
globular clusters: individual: NGC 6205 -
globular clusters: individual: NGC 7099
Abstract:
Globular clusters are main astrophysical laboratories to test and
modify evolutionary models. Thought to be rather homogeneous in their
local elemental distribution of members, results suggest a wide
variety of chemical peculiarities. Besides different main sequences,
believed to be caused by different helium abundances, peculiarities of
blue horizontal-branch stars and on the red giant branch were found.
This whole zoo of peculiar objects has to be explained in the context
of stellar formation and evolution. The tool of Δa photometry is
employed in order to detect peculiar stars in the whole spectral
range. This three filter narrow-band system measures the flux
distribution in the region from 4900 to 5600Å in order to find any
peculiarities around 5200Å. It is highly efficient to detect
classical chemically peculiar stars of the upper main sequence, Be/Ae,
shell and metal-weak objects in the Milky Way and Magellanic Clouds.
We present Δa photometry of 2266 stars from 109 individual
frames for three globular clusters (NGC 104, NGC 6205, and NGC 7099).
A comparison with published abundances, for three horizontal-branch
stars, only, yields an excellent agreement. According to the 3σ
detection limit of each globular cluster, about 3 percent of the stars
lie in abnormal regions in the diagnostic diagrams. The first
observations of three widely different aggregates give very promising
results, which will serve as a solid basis for follow-up observations
including photometric as well as spectroscopic studies.
Description:
The observations of the three globular clusters were performed at two
different sites:
* 2m Ritchey-Chretien-Coude telescope [Bulgarian National Astronomical
Observatory (BNAO, Rozhen)], direct imaging, SITe SI003AB
1024x1024-pixel CCD, 5' field of view, 1pixel=0.32arcsec, and
* 2.15m telescope [El Complejo Astronomico El Leoncito (CASLEO)], direct
imaging with focal reducer, TEK-1024 CCD, 9.5-arcmin field of view,
1pixel=0.813arcsec.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
00 24 05.36 -72 04 53.2 NGC 104 = 47 Tuc
16 41 41.63 +36 27 40.7 NGC 6205 = M 13
21 40 22.12 -23 10 47.5 NGC 7099 = M 30
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
ngc104.dat 73 1107 NGC 104 complete photometric data of the
programme stars
ngc6205.dat 73 365 NGC 6205 complete photometric data of the
programme stars
ngc7099.dat 73 794 NGC 7099 complete photometric data of the
programme stars
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See also:
II/248 : UBV photometry and proper motions in M13 (Kadla, 1966)
J/AJ/112/1061 : BV photometry of NGC 7099 (Bergbusch 1996)
J/AJ/113/669 : Stars in M13 core (Cohen+ 1997)
J/AJ/116/1757 : M30 UBV photometry (Guhathakurta+, 1998)
J/ApJ/518/262 : CCD VIc Photometry of M30 Stars (Sandquist+, 1999)
J/A+A/398/541 : VI light-curves of the variable stars in M13 (Kopacki+, 2003)
J/AJ/129/303 : Abundances of stars in M3 and M13 (Cohen+, 2005)
J/A+A/462/L9 : Radial velocities in NGC 7099 (Scarpa+, 2007)
J/ApJ/657/286 : Chandra X-ray sources in M30 (NGC 7099) (Lugger+, 2007)
J/AJ/143/50 : White dwarfs in 47 Tuc (NGC 104) with HST (Woodley+, 2012)
J/ApJ/754/L38 : Abundances and radial velocities of M13 giants (Johnson+, 2012)
J/A+A/555/A36 : VrI light curves of NGC7099 variables (Kains+, 2013)
J/ApJ/772/148 : Blue straggler and red giant stars in M30 (Lovisi+, 2013)
J/A+A/566/A58 : Radial velocities in M3, M13, and M92 (Kamann+, 2014)
J/ApJ/780/94 : Abundances of red giants in 47 Tuc (Cordero+, 2014)
Byte-by-byte Description of file: ngc104.dat ngc6205.dat ngc7099.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq Star sequential number within the cluster
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
30- 35 F6.3 mag g1-y [-1.3/0.3] g1-y colour index (1)
37- 41 F5.3 mag e_g1-y [0/0.05] rms uncertainty on g1-y
43- 47 F5.3 mag amag [0.2/1.0] a index (1)
49- 53 F5.3 mag e_amag [0/0.05] rms uncertainty on amag
55- 60 F6.3 mag Da [-0.09/0.11] Intrinsic peculiarity index
Δa (2)
62- 67 F6.3 mag Vmag V magnitude
69- 73 F5.3 mag e_Vmag rms uncertainty on Vmag
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Note (1): a index defined as (Maitzen 1976A&A....51..223M 1976A&A....51..223M)
a = g2-(g1+y)/2, from
g1 = λc=5007Å, FWHM=126Å),
g2 = λc=5199Å, FWHM=95Å) and
y = λc=5466Å, FWHM=108Å).
Note (2): defined as the difference between the a-value of the studied star
and a0, a-value for non-peculiar star of the same colour.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 16-Apr-2015