J/A+A/372/477 ubvyβ photometry of h & chi Persei (Marco+, 2001)
Photometric study of the double cluster h & χ Persei
Marco A., Bernabeu G.
<Astron. Astrophys. 372, 477 (2001)>
=2001A&A...372..477M 2001A&A...372..477M
ADC_Keywords: Clusters, open ; Photometry, uvby, beta
Keywords: techniques: photometric - Galaxy: open clusters and associations:
individual: h Persei, chi Persei - stars: evolution -
emission-line, Be - formation
Abstract:
We present uvbyβ CCD photometry of the central region of the
double cluster h&χ Persei. We identify ≃350 stars, of which 214
were not included in Oosterhof's catalogue. Our magnitude limit V=16.5
allows us to reach early F spectral type and obtain very accurate fits
to the ZAMS. We derive reddening values of E(b-y)=0.44±0.02 for h
Persei and E(b-y)=0.39±0.05 for χ Persei. From the ZAMS fitting,
we derive distance moduli
V0-MV=11.66±0.20 and V0-MV=11.56±0.20
for h and χ Persei respectively.
These values are perfectly compatible with both clusters being placed
at the same distance and having identical reddenings. The shift in the
main-sequence turnoff and isochrone fitting, however, show that there
is a significant age difference between both clusters, with the bulk
of stars in h Persei being older than χ Persei. There is, however,
a significant population of stars in h Persei which are younger than
χ Persei. All this argues for at least three different epochs of
star formation, corresponding approximately to logt=7.0, 7.15 and 7.3.
Objects:
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RA (2000) DE Designation(s)
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02 22 24 +57 07.0 NGC 884 = chi PER
02 19 00 +57 09.0 NGC 869 = h PER
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2a.dat 49 91 *New stars in h Persei (not in Oosterhoff catalog)
table2b.dat 49 125 *New stars in χ Persei, not in Oosterhoff catalog
table8.dat 82 165 Stromgren photometry of member of h Per
table9.dat 82 137 Stromgren photometry of member of χ Per
table14a.dat 35 157 Intrinsic photometry of member of h Per
table14b.dat 31 132 Intrinsic photometry of member of χ Per
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Note on table2a.dat, table2b.dat: Oosterhoff, 1937AnLei..17a...1O 1937AnLei..17a...1O
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See also:
V/27 : Proper Motions and UBV Photometry in h+chi Per (Muminov 1980)
Byte-by-byte Description of file: table2a.dat table2b.dat
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Bytes Format Units Label Explanations
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1- 4 I4 ---- Name Name of the source (1)
7 I1 ---- Frame [1/2] 1 for h Persei and 2 for χ Persei
10- 17 F8.3 pix Xpix X Position in pixel (2)
20- 27 F8.3 arcsec Xpos X Position in arcsec
30- 37 F8.3 pix Ypix Y position in pixel (2)
41- 47 F7.3 arcsec Ypos Y position in arcsec
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Note (1): Number references for stars:
4NNN: stars in the field of h Persei
7NNN: stars in the field of χ Persei
Note (2): Origin of the coordinates:
Frame 1 (h Per): RA = 2 15 9.42 (1950) DE = +56 57 6.87
Frame 2 (chi Per): RA = 2 18 7.58 (1950) DE = +56 57 21.05
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Byte-by-byte Description of file: table8.dat table9.dat
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Bytes Format Units Label Explanations
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1- 4 I4 ---- Name Name of the source (1)
7- 12 F6.3 mag Vmag V magnitude
15- 19 F5.3 mag b-y b-y colour index
22- 27 F6.3 mag m1 m1 colour index
30- 34 F5.3 mag c1 c1 colour index
37- 41 F5.3 mag beta ? β colour index
44- 48 F5.3 mag e_Vmag ? Standard deviation in Vmag
51- 55 F5.3 mag e_b-y ? Standard deviation in b-y
58- 62 F5.3 mag e_m1 ? Standard deviation in m1
65- 69 F5.3 mag e_c1 ? Standard deviation in c1
72- 76 F5.3 mag e_beta ? Standard deviation in beta
79 I1 --- o_uvby Number of measurements in each filter
81 I1 --- o_beta Number of measurement in beta
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Note (1): The nomenclature is that of Oosterhoff (1937AnLei..17a...1O 1937AnLei..17a...1O).
Those stars that were not observed by Oosterhoff (1937AnLei..17a...1O 1937AnLei..17a...1O)
are listed after a "4" prefix for h Persei field,
and a "7" prefix for χ Persei field.
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Byte-by-byte Description of file: table14a.dat table14b.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Name Name of the source
6- 11 F6.3 mag V0mag V0 magnitude
13- 18 F6.3 mag (b-y)0 (b-y)0 colour index
20- 26 F7.4 mag c0 c0 index
28- 31 A4 --- SpType Spectral Type (1)
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Note (1): Unless otherwise indicated in the text, luminosity class is always
taken to be V.
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Acknowledgements: Amparo Marco
(End) Patricia Bauer [CDS] 23-Mar-2001