| Issue |
A&A
Volume 372, Number 2, June III 2001
|
|
|---|---|---|
| Page(s) | 477 - 494 | |
| Section | Galactic structure, stellar clusters, and populations | |
| DOI | https://doi.org/10.1051/0004-6361:20010441 | |
| Published online | 15 June 2001 | |
Photometric study of the double cluster 
& 
Persei*,**
Dpto. de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Aptdo. de Correos 99, 03080, Alicante, Spain
Corresponding author: A. Marco, amparo@astronomia.disc.ua.es
Received:
20
July
2000
Accepted:
28
January
2001
We present 
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 
allows us to reach early F spectral type
and obtain very accurate fits to the ZAMS. We derive reddening values of
for h Persei and 
for
χ Persei. From the ZAMS fitting, we derive distance moduli
and 
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 
and 7.3.
Key words: techniques: photometric / Galaxy: open clusters and associations: individual: h Persei, χ Persei / stars: evolution / emission-line, Be / formation
© ESO, 2001
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