J/A+A/567/A73 Photometry of VdBH 222 stars and field stars (Marco+, 2014)
VdBH 222: a starburst cluster in the inner Milky Way.
Marco A., Negueruela I., Gonzalez-Fernandez C., Maiz Apellaniz J., Dorda R.,
Clark J.S.
<Astron. Astrophys. 567, A73 (2014)>
=2014A&A...567A..73M 2014A&A...567A..73M
ADC_Keywords: Clusters, open ; Photometry, UBVRI ; Photometry, infrared
Keywords: Hertzsprung-Russell and C-M diagrams - stars: evolution -
stars: early-type - supergiant - techniques: photometric -
techniques: spectroscopic
Abstract:
It has been suggested that the compact open cluster VdBH 222 is a
young massive distant object.
We set out to characterise VdBH 222 using a comprehensive set of
multi-wavelength observations.
We obtained multi-band optical (UBVR) and near-infrared (JHKs)
photometry of the cluster field, as well as multi-object and long-slit
optical spectroscopy for a large sample of stars in the field. We
applied classical photometric analysis, as well as more sophisticated
methods using the CHORIZOS code, to determine the reddening to the
cluster. We then plotted dereddened HR diagrams and determined cluster
parameters via isochrone fitting.
Description:
We obtained UBVR photometry of VdBH 222 using the ESO Faint Object
Spectrograph and Camera (EFOSC2) on the NTT on the night of 24 June
2012. The instrument was equipped with CCD#40, which is a
Loral/Lesser, thinned, AR-coated, UV-flooded, and MPP chip that is
controlled by ESO-FIERA. It covers a field of view of and 4.1'x4.1'
and has a pixel scale of 0.12". The JHK images were obtained using the
Son OF Isaac (SOFI) near-IR spectrograph and camera on the NTT on 13
July 2008, equipped with a CCD providing a pixel scale of 0.288arcsec
and an field of view of 4.92x4.95'
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 34 59 Photometric values for likely members with
(U-B) colour
table5.dat 20 84 Photometric values for likely members without
(U-B) colour
table7.dat 84 1004 Optical photometry and coordinates for stars in
the field of the open cluster VdBH 222
table8.dat 72 2180 Near-infrared photometry and coordinates for
stars in the field of the open cluster VdBH 222
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1 A1 --- Type [MGB] Star type: Main-sequence, Giant or
Blue supergiant
3- 6 I4 --- Star [59/1069] Star identification (number)
8- 12 F5.2 --- Q Q parameter for each likely member (1)
14- 17 A4 --- SpType MK spectral type for each likely member (2)
19- 23 F5.2 mag (B-V)0 Intrinsic colour (B-V)0 for each likely
member (3)
25- 28 F4.2 mag E(B-V) Individual values of the colour excess E(B-V)
for each likely member (4)
30- 34 F5.2 mag V0 Instrinsic magnitudes V0for each likely
member (5)
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Note (1): The Q parameter (Johnson & Morgan, 1953ApJ...117..313J 1953ApJ...117..313J,
Johnson, 1958LowOB...4...37J 1958LowOB...4...37J) is calculated as: Q=(U-B)-0.82(B-V).
Note (2): Using Q, we assigned photometric spectral types (Johnson & Morgan,
1953ApJ...117..313J 1953ApJ...117..313J) to all these stars.
Note (3): from Johnson (1958LowOB...4...37J 1958LowOB...4...37J) for supergiants (V≤17),
giants (17≤V≤18.5) and main-sequence (V≥18.5).
Note (4): From the spectral types, we calculated individual values of the
colour excess E(B-V), using the intrinsic colours from the column 4 and
the equation E(B-V)=(B-V)-(B-V)0.
Note (5): The intrinsic magnitudes are calculated as: V0=V-2.90*E(B-V)
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1 A1 --- Type [MGB] Star type: Main-sequence, Giant or
Blue supergiant
3- 6 I4 --- Star [34/1043] Star identification (number)
8- 13 F6.3 mag (B-V)0 Intrinsic colour (B-V)0 for each likely
member (1)
15- 20 F6.3 mag V0 Instrinsic magnitudes V0for each likely
member (2)
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Note (1): We use the following expression: (B-V)0=(B-V)-E(B-V) where
E(B-V)=2.45±0.15 is the average colour excess for the cluster. This average
is calculated using only the stars believed to be on the main-sequence showed
in Table 4.
Note (2): The intrinsic magnitudes are calculated as: V0=V-2.90*2.45.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Star [17/1078] Star identification (number)
6- 7 I2 h RAh Right ascension J2000 (1)
9- 10 I2 min RAm Right ascension J2000 (1)
12- 16 F5.2 s RAs Right ascension J2000 (1)
18 A1 --- DE- Declination sign (J2000) (1)
19- 20 I2 deg DEd Declination (J2000) (1)
22- 23 I2 arcmin DEm Declination (J2000) (1)
25- 28 F4.1 arcsec DEs Declination (J2000) (1)
30- 35 F6.3 mag Vmag V magnitude
37- 41 F5.3 mag e_Vmag Error for V magnitude (2)
43 I1 --- o_Vmag Number of measurements for V magnitude
45- 49 F5.3 mag B-V B-V colour index
51- 55 F5.3 mag e_B-V Error for B-V colour index (2)
57 I1 --- o_B-V Number of measurements for B-V colour index
59- 63 F5.3 mag U-B ?=- U-B colour index (3)
65- 70 F6.4 mag e_U-B ?=- Error for U-B colour index (2)
72- 76 F5.3 mag V-R ?=- V-R colour index
78- 82 F5.3 mag e_V-R ?=- Error for V-R colour index (2)
84 I1 --- o_V-R ? Number of measurements for V-R colour index
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Note (1): Formal rms uncertainties of the astrometric fit for our images are
<0.10" in both right ascension and declination.
Note (2): The error in each fitted value is computed by summing in quadrature
the contribution to the total error made by each individual error in the
observations files variables.
Note (3): The number of measurements in (U-B) is always 1.
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [45/3677] Field star identification (number)
6- 9 I4 --- Star [17/1078]? Star identification (number) in
Table 7 (if existing). Only 480 stars have
optical photometry too
11- 12 I2 h RAh Right ascension J2000 (1)
14- 15 I2 min RAm Right ascension J2000 (1)
17- 21 F5.2 s RAs Right ascension J2000 (1)
23 A1 --- DE- Declination sign (J2000) (1)
24- 25 I2 deg DEd Declination (J2000) (1)
27- 28 I2 arcmin DEm Declination (J2000) (1)
30- 33 F4.1 arcsec DEs Declination (J2000) (1)
35- 40 F6.3 mag Jmag J magnitude (2)
42- 46 F5.3 mag e_Jmag Error for J magnitude
48- 53 F6.3 mag Hmag H magnitude (2)
55- 59 F5.3 mag e_Hmag Error for H magnitude
61- 66 F6.3 mag Ksmag ?=- Ks magnitude (2)
68- 72 F5.3 mag e_Ksmag ?=- Error for Ks magnitude
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Note (1): Formal rms uncertainties of the astrometric fit for our images are
<0.10" in both right ascension and declination.
Note (2): The number of measurements is 1.
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Acknowledgements:
Amparo Marco, amparo.marco(at)ua.es
(End) Patricia Vannier [CDS] 04-May-2014