The young open cluster Markarian 50

Abstract

We report on a deep CCD UBV(RI) C photometric survey in the region of the young open cluster Markarian 50. The new photometric data allow us to extend the cluster membership down to V ≈ 17.5, about 2 mag deeper than any previous investigation. On the basis of these data we derive a distance d = 3460 ± 350 pc (V O − M V = 12.7 ± 0.2), which turns out to be only slightly lower than previous estimates. The cluster presents differential reddening, with E(B-V ) values ranging from 0.69 to 1.1. The brightest member (HD 219460) is a double star, which we separate photometrically for the first time, providing individual magnitudes and colours for each component. One of them is a Wolf-Rayet (WR) star and, according to evolutionary models, the mass of its progenitor should be greater than ∼20 M . The age obtained for the cluster is 7.5 ± 2 Myr and the mass function for the most massive stars (M > 1 M ) presents a slope x ≈ 1.0.

Multiwavelength study of a young open cluster NGC 7419

“…5), in which the isochrones (Girardi et al 2002, hereafter GRD02) are found to fit well with X = 0.90. Such anomalous values of X are not uncommon for the interstellar matter in the Milky Way and a higher value of X (>0.72) has also been reported along lines of sight of other star‐forming clusters, for example, NGC 869 ( X = 0.90; Pandey et al 2003); Markarian 50 ( X = 0.81; Baume, Vázquez & Carraro 2004) and NGC 7510 ( X = 0.78; Barbon & Hassan 1996). However, they report normal value for other colour excesses in these clusters.…”

Spatial distribution of Galactic Wolf–Rayet stars and implications for the global population

“…Distance references (1-22 as in Table 1): (23) Arnal et al (1999), (24)Crowther, Smith & Hillier (1995b), (25) Tovmassian, Navarro & Cardona (1996), (26) Howarth & Schmutz (1995), (27) Cappa et al (1999), (28) , (29) Garmany & Stencel (1992), (30) Bohannan & Crowther (1999). Photometry references (a-g as in Table 1): (h) Cotera et al (1999), ( Distribution of Galactic Wolf-Rayet stars 9 Baume, Vázquez & Carraro (2004). Photometry references (a-l as in Tables 1 & 2): (m) Williams et al (1990b), (n) Williams et al (2001 Lortet, Testor & Niemela (1984), (WR 127) de La Chevrotière, , (WR 133) Underhill & Hill (1994), (WR 137) Williams et al (2001), (WR 139) Marchenko, Moffat & Koenigsberger (1994), (WR 141) Marchenko, Moffat & Eenens (1998), (WR 157) Smith et al (1996).…”

Variability survey of brightest stars in selected OB associations

“…During periods with very few provided flats, we constructed master flats from frames of a single night with minimal time separation from the observations. Scattered light reaching the focal plane of the camera causes illumination gradients in flat-field frames and using these flat fields in the data reduction may yield position-dependent Joshi et al (1983); (g) Massey et al (1995); (h) Wright et al (2014); (i) Maciejewski & Niedzielski (2007); ( j) Barbon & Hassan (1996); (k) Piskunov et al (2004); (l) Baume et al (2004); (m) Choi et al (1999); (n) Pandey (1986); (o) Sanner et al (1999); (p) Georgy et al (2014); (q) Pandey et al (2005); (r) Pigulski et al (2001); (s) Tetzlaff et al (2010) 5 ; (t) Currie et al (2010); (u) Yadav et al (2008); (v) Wolff et al (2011). systematic uncertainties in the resulting photometry (Manfroid 1995). The T4 telescope had a German equatorial mount and due to the aforementioned scattered light problem, the data show systematic effects depending on the telescope being on the east or west side of the pier.…”