The Pre-Main-Sequence Stars and Initial Mass Function of NGC 2264
UBVRI and Hα CCD photometry has been performed in the southernregion of NGC 2264 around the Cone Nebula. A nearly complete list ofpre-main-sequence (PMS) members in the cluster has been made from thecompilation of Hα emission stars identified in this study plusthose selected in previous investigations, together with stars withX-ray emission. Using the H-R diagram, we tested a set of four PMSevolution models based on the PMS age and age spread estimate for thecluster and the mass-age relationship among individual stars. Theresultant initial mass function (IMF) is in good agreement with thefield star IMF of the solar neighborhood, with an IMF slope Γ=-1.7in the mass range 0.3<=logm<=0.8.
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Spectral classification of O-M stars on the basis of UBV photometry
A new technique allowing the Q-method to be used surely for both thespectral classification of young O-A0 stars and older spectralsubclasses A1-M5 is described. Characteristics of interstellar lightabsorption dependence on distance in the given direction of the sky isused as a main criterion for excluding possible multiplicity of starspectral estimates at some constant values of QUBV.Information on open cluster membership probabilities is also useful asadditional criterion of the spectral classification. The method wastested on stars up to V=14 mag in directions of young open clusters NGC2244 and NGC 2264. The spectral study based on UBV photometry wasextended to faint stars of NGC 2264 in the V magnitude range 17-22 mag.
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BVRI photometry of the star-forming region NGC 2264: the initial mass function and star-forming rate
The pre-main sequence (PMS) population in the mass range between ~ 0.2and ~ 3 M_sun in southern part of the star-forming region NGC 2264 hasbeen studied, determining both the Initial Mass Function in the regionas well as the star-formation rates for different mass ranges. Thesample is a composite one, derived through the union of samples obtainedthrough different techniques and each suffering from different biases:previously known PMS stars in the region from the literature,photometrically-selected T Tauri candidates (from our own photometricdata, discussed in detail in the present paper) and X-ray selected PMScandidates (discussed in detail in a companion paper) have been joinedto form a sample which we show to be statistically complete (i.e. freefrom the biases which affect each of the parent samples) down to =~ 0.6M_sun (while being incomplete at lower masses). Individual masses andages have been derived by placing the individual stars on evolutionarytracks, allowing us to derive both the IMF and the star formation rate.The Initial Mass Function thus derived for NGC 2264 shows evidence for abimodal distribution of masses, with a break in the IMF at around 1M_sun. Based on observations with the VATT: the Alice P. LennonTelescope and the Thomas J. Bannan Astrophysics Facility. Table~3 isavailable in electronic form at CDS via ftp 130.79.128.5
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VBLUW photometry of the very young open cluster NGC 2264
This study presents and discusses VBLUW photometry of 112 stars with Vless than 13 in the area of the very young cluster NGC 2264.Temperatures, gravities, and reddening for stars hotter than 8400 K aredetermined. The reddening and the distance are found to be in goodagreement with the results of other references; to the existing list ofpresumable nonmembers, six stars are tentatively added as possiblenonmembers.
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Remarks to Lapicz positions of stars in NGC 2264.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990RMxAA..20..113L&db_key=AST
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Ultraviolet and X-ray observations of NGC 2264
An IUE satellite search is reported for chromospheric emission in the UVspectra of the brightest pre-main sequence stars the open cluster NGC2264. Einstein X-ray observations to search for variability of thebright O7 V ((f)) star S Mon = W131, which may be the most massivemember of the cluster, are also reported. Fifteen cluster members ofspectral type B-K, ranging in age from a million to ten million yr, wereobserved in the ultraviolet. The only star exhibiting chromosphericemission is W79, a faint, heavily veiled T Tauri star that lies belowthe main sequence of NGC 2264. The observations are consistent with thegenerally accepted idea that chromospheric activity of late-type starssubsides with age.
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Positions of stars in NGC 2264
Positions in the region of NGC 2264, obtained using the Lick CarnegieAstrograph are presented. The methods used to obtain the positions arebriefly discussed.
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Circumstellar shells in NGC 2264 : a reevaluation.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977ApJ...213..427W&db_key=AST
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Pre-Main Stars. I. Light Variability, Shells, and Pulsation in NGC 2264
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972ApJ...171..539B&db_key=AST
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The distribution of stars and obscuring matter in a Monoceros field
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&AS....7...35K&db_key=AST
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Catalogue des étoiles mesurées dans le système photométrique de l'Observatoire de Genève
Not Available
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Studies of Extremely Young CLUSTERS.I.NGC 2264.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956ApJS....2..365W&db_key=AST
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