O-like Stars in the Direction of the North America and Pelican Nebulae

In the area covering the complex of the North America and Pelican nebulae we identified 13 faint stars with J-H and H-Ks color indices which simulate heavily reddened O-type stars. One of these stars is CP05-4 classified as O5 V by Comeron and Pasquali (2005). Combining magnitudes of these stars in the passbands I, J, H, Ks and [8.3] we were able to suspect that two of them are carbon stars and five are late M-type AGB stars. Interstellar extinction in the direction of these stars was estimated from the background red clump giants in the J-H vs. H-Ks diagram and from star counts in the Ks passband. Four or five stars are found to have a considerable probability of being O-type stars, contributing to the ionization of North America and Pelican. If they really are O-type stars, their interstellar extinction A(V) should be from 16 to 35 mag. Two of them seem to be responsible for bright E and J radio rims discovered by Matthews and Goss (1980).Comment: 17 pages, 6 figure

Young stars and clouds in Camelopardalis

Star formation in the Local spiral arm in the direction of the Galactic longitudes 132--158 deg is reviewed. Recent star-forming activity in this Milky Way direction is evidenced by the presence here of the Cam OB1 association and dense dust and molecular clouds containing H$\alpha$ emission stars, young irregular variables and infrared stellar objects. The clouds of the Local arm concentrate in two layers at 150-300 pc and at about 900 pc from the Sun. The Perseus arm objects in this direction are at a distance of about 2 kpc.Comment: 14 pages, 6 figure

Extinctions and distances of dark clouds from UGRIJHK photometry of red clump giants: the North America and Pelican nebulae complex

A possibility of applying 2MASS J, H, Ks, IPHAS r, i and MegaCam u, g photometry of red giants for determining distances to dark clouds is investigated. Red clump giants with a small admixture of G5-K1 and M2-M3 stars of the giant branch can be isolated and used in determining distances to separate clouds or spiral arms. The method is applied to an area of the North America and Pelican nebulae complex. Interstellar extinctions of background red giants can be also used for mapping dust surface density in the cloud.Comment: 19 pages, 8 figure

Young Stars in the Camelopardalis Dust and Molecular Clouds. II. Infrared Objects

Using infrared photometric data extracted from the 2MASS, IRAS and MSX databases, 142 suspected young stellar objects (YSOs) are selected from about 2 million stars in the Camelopardalis segment of the Milky Way limited by Galactic longitude 132-158 deg, latitude pm 12 deg. According to radial velocities of the associated CO clouds, the objects are attributed to three molecular and dust cloud layers at 150--300 pc, 900 pc and 2.2 kpc distances from the Sun. These objects concentrate into dust and molecular clouds and exhibit extremely large reddenings (A_V up to 25 mag) which can be caused by the dust in foreground clouds and circumstellar envelopes or disks. In the J-H vs. H-K diagram these objects lie above the intrinsic line of T Tauri variables, roughly along the black-body line. Among the identified objects, some already known YSOs are present, including the well investigated massive object GL 490. The spectral energy distributions between 700 nm and 100 mum suggest that the objects may be YSOs of classes I, II and III. However, we do not exclude the possibility that a small fraction of the objects, especially those without IRAS and MSX photometry, may be unrecognized heavily reddened OB-stars, late-type AGB stars or even galaxies

2MASS Two-color Interstellar Reddening Line in the Direction of the North America and Pelican Nebulae and the Cyg OB2 Association

The slope of the interstellar reddening line in the J-H vs. H-Ks diagram of the 2MASS survey in the direction of the North America and Pelican nebulae, the L935 dust cloud and the Cyg OB2 association is determined. The MK types were either classified by C. J. Corbally or collected from the literature. The ratio E(J-H)/E(H-Ks) = 2.0 is obtained by taking the average for the four groups of spectral classes: O3--B1, B2--B6, B7--B9.5 and red clump giants. The obtained ratio is larger than the `typical' value, 1.7-1.8.Comment: 18 pages, 6 figure

Spectral analysis of YSOs and other emission-line stars in the North America and Pelican nebulae region

Far red spectra for 34 stars with V magnitudes between 15 and 18 in the direction of the North America and Pelican nebulae (NAP) star-forming region are obtained. Some of these stars were known earlier as emission-line objects, others were suspected as pre-main-sequence stars from photometry in the J, H, Ks and Vilnius systems. We confirm the presence of the H alpha line emission in the spectra of 19 stars, some of them exhibit also emission in the O I and Ca II lines. In some of the stars the H alpha absorption line is filled with emission. To estimate their evolutionary status, the spectral energy distributions, based on Vilnius, 2MASS, MSX and Spitzer photometry, are applied. Only eight emission-line stars are found to be located at a distance of the NAP complex. Others are either chromospherically active stars in front of the complex or distant luminous stars with H alpha absorption and emission components. For five stars with faint emission the data are not sufficient to estimate their distance. One star is found to be a heavily reddened K-supergiant located in the Outer arm. The stars, for which we failed to confirm the emission in H alpha, are mostly red dwarfs located in front of the NAP complex, two of them could be binaries with L-type components. Taking into account the stars suspected to be YSOs by their 2MASS colors we conclude that the NAP complex can possess a considerable population of young stars hidden behind the dust cloud.Comment: 29 pages, 6 figure

Young Stars in the Camelopardalis Dust and Molecular Clouds. I. The Cam OB1 Association

The distribution of dust and molecular clouds in the direction of Galactic longitudes 132--158 deg and latitudes pm 12 deg is investigated. The maps of dust distribution in the area were plotted from the following surveys: the star counts in the DSS I database by Dobashi et al. (2005), the survey of the average infrared color excesses by Froebrich et al. (2007) and the thermal dust emission survey at 100 micrometers by Schlegel et al. (1998). The distribution of molecular clouds was taken from the whole sky CO survey by Dame et al. (2001). All these surveys show very similar cloud patterns in the area. Using the radial velocities of CO, the distances to separate clouds are estimated. A revised list of the Cam OB1 association members contains 43 stars and the open cluster NGC 1502. 18 young irregular variable and H alpha emission stars are identified in the area. All this proves that the star forming process in the Camelopardalis clouds is still in progress

Young Stars in the Camelopardalis Dust and Molecular Clouds. III. the GL 490 Region

Using the infrared photometry data extracted from the 2MASS, IRAS and MSX databases, 50 suspected young stellar objects (YSOs) are selected from about 37500 infrared objects in the 3x3 deg area with the center at Galactic longitude 142.5 deg and latitude +1.0 deg, in the vicinity of the young stellar object GL 490 in the dark cloud DoH 942 (Dobashi et al. 2005). The spectral energy distributions between 700 nm and 100 mum suggest that most of the selected objects may be YSOs of classes I and II. In the color-magnitude diagram K_s vs. H-K_s the suspected YSOs occupy an area right of the main sequence what can be interpreted as being caused by the effects of luminosity, interstellar and circumstellar reddening and infrared thermal emission in circumstellar envelopes and disks

CCD photometry and classification of stars in the North America and Pelican nebulae region. I. Moletai photometry

Magnitudes and color indices in the Vilnius seven-color system are measured for 690 stars down to ~13.2 mag in the area of the North America and Pelican nebulae. Spectral types, absolute magnitudes, color excesses, interstellar extinctions and distances of the stars are determined. The plots of interstellar extinction Av versus distance for the North America Nebula and for the dark cloud L935 show that both areas are covered by the same absorbing cloud, situated at a distance of 600 pc. The maximal extinction in the area of the nebula is ~3 mag, while in the dark cloud L935 it is much greater.Comment: 14 pages, 6 figures to be published in Baltic Astronomy journa

The open cluster NGC 7142: interstellar extinction, distance and age

The results of medium-band photometry of 1037 stars in the area of old open cluster NGC 7142 down to V = 20.1 mag in the Vilnius seven-colour system are presented. Photometric results are used to classify in spectral and luminosity classes about 80 percent of stars down to V = 18.5 mag, to identify cluster members, to determine the main cluster parameters and to investigate the interstellar extinction in this direction. The average extinction A_V of the cluster is about 1.1 mag, E(B-V) = 0.35, and its distance is 2.3 kpc (the distance modulus 11.8 mag). The age of the cluster, 3.0 Gyr, is estimated from the intrinsic colour-magnitude diagram with individual dereddening of each star and the Padova isochrones. The surface distribution of the extinction is shown. The reddening of the eclipsing variable V375 Cep is found to be close to the average reddening of the cluster. Probably, the cluster contains five red clump giants, two asymptotic branch stars and four blue stragglers.Comment: 8 pages, 6 fugures, full Table 2 online. Bibliographic code 2013MNRAS.tmp2648S, DOI: 10.1093/mnras/stt199