Young Open Cluster NGC Research Articles

A PROBABLE PLANETARY NEBULA IN THE DIRECTION OF THE YOUNG OPEN CLUSTER NGC 3572

ABSTRACT The discovery of a ringlike emission feature located along the time of sight toward the young open cluster NGC 3572 is reported. The small feature is prominent in H-alpha but has no central star brighter than magnitude V about 20 and is barely detectable in U, B, and V frames. The appearance of the ring is consistent with it being a PN at an unknown distance.

The inner and outer membership regions of the young open cluster NGC 6823

The inner and outer membership regions of the young open cluster NGC 6823

ON THE DISTANCES TO THE YOUNG OPEN CLUSTERS NGC 2244 AND NGC 2264.

ABSTRACT A new determination of the distances of the young open clusters NGC 2244 and NGC 2264 is presented. It is based on distance moduli for individual OB-type stars in which the influence of the anomalous ratio of total to selective extinction, if any, is taken into account. A discussion is included, first, of the accuracy of the color-difference method compared to that of other current methods for determining R and, second, of the errors in the determination of the distances for clusters embedded in nonuniform H II regions. New photoelectric measurements (UBVRI and JHKLM), and new spectrophotometric data (IDS spectra) are presented for OB-type stars in these clusters as well as summaries of published photometric data. The locations in the H-R diagram of the program stars seem to suggest that these massive stars are on the main sequence, supporting the idea of continuous star formation.

A study of the nature of the H?-emission stars LkH?112, 115, 118, and 119

The present study of the nature of the stars LkHα112, LkHα115, LkHα118, and LkHα119 is based on low-dispersion IDS spectra and photometric measurements in the wavelength range between 0.33 and 3.8 μm. These stars are located in the direction of the extremely young open cluster NGC 6530 (Walker, 1957). The purpose of this study is, in general, to know whether they belong to the group of intermediate mass pre-main sequence objects, also known as Herbig Ae/Be stars, and, in particular, what special characteristics they possess. The result is as follows. The stars are very young; probably only LkHα112 and LkHα115 are members of the above-mentioned class of objects. The membership of LkHα118 and LkHα119 in this group is doubtful.

The young open cluster NGC 346 in the Small Magellanic Cloud

Resultats d'observations spectrographiques et photometriques CCD des etoiles de l'amas NGC 346 qui excitent la plus grande region HII du PNM

Study of the region of star formation 2 mon. The region of the cluster NGC 2244

This paper studies the distribution and density of the dust in the central part region of star formation 2 Mon in the young open star cluster NGC 2244. The ring of the cluster coincides with the ring emission of the Rosette nebula, and the nucleus of the cluster contains five O stars and is in the emission hole. On the basis of data from the author's catalog of B and V magnitudes and the spectra of O-B-A stars, and also data on UBV photometry and proper motions, it is concluded that there is no dust in the eastern half of the ring of maximal emission of the Rosette nebula.

The star-forming history of the young cluster NGC 2264

view Abstract Citations (80) References (58) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The star-forming history of the young cluster NGC 2264. Adams, M. T. ; Strom, K. M. ; Strom, S. E. Abstract UBVRI H-alpha photographic photometry was obtained for a sample of low-mass stars in the young open cluster NGC 2264 in order to investigate the star-forming history of this region. A theoretical H-R diagram was constructed for the sample of probable cluster members. Isochrones and evolutionary tracks were adopted from Cohen and Kuhi (1979). Evidence for a significant age spread in the cluster was found amounting to over ten million yr. In addition, the derived star formation rate as a function of stellar mass suggests that the principal star-forming mass range in NGC 2264 has proceeded sequentially in time from the lowest to the highest masses. The low-mass cluster stars were the first cluster members to form in significant numbers, although their present birth rate is much lower now than it was about ten million yr ago. The star-formation rate has risen to a peak at successively higher masses and then declined. Publication: The Astrophysical Journal Supplement Series Pub Date: December 1983 DOI: 10.1086/190913 Bibcode: 1983ApJS...53..893A Keywords: Main Sequence Stars; Star Clusters; Stellar Evolution; Stellar Spectrophotometry; Galactic Clusters; Open Clusters; Protostars; Star Formation Rate; Stellar Luminosity; Stellar Mass; Astrophysics full text sources ADS | data products SIMBAD (7)

Membership of the Rosette Nebula cluster, NGC 2244

view Abstract Citations (37) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Membership of the Rosette nebula cluster NGC 2244. Marschall, L. A. ; van Altena, W. F. ; Chiu, L. -T. G. Abstract Relative proper motions for 287 stars in the region of the young open cluster NGC 2244, located in the Rosette Nebula, have been determined from plates taken with the Yerkes 40-in. and the Allegheny 30-in. refractors. Probabilities of membership based on these proper motions are derived. Because probable members are chosen primarily from kinematic considerations, the sample should show a minimum photometric bias. Differential extinction across the cluster, however, is identified as a complication in the immediate interpretation of the sample in terms of color-magnitude diagrams or luminosity functions. Publication: The Astronomical Journal Pub Date: November 1982 DOI: 10.1086/113240 Bibcode: 1982AJ.....87.1497M Keywords: Early Stars; Nebulae; Star Clusters; Interstellar Extinction; Open Clusters; Photometry; Stellar Color; Stellar Luminosity; Stellar Motions; Tables (Data); Astronomy full text sources ADS | data products SIMBAD (2)

IUE observations of eight OB stars in NGC 2244 - Ultraviolet continua and extinction

Low-resolution IUE ultraviolet continuum observations of O and B stars in the young open cluster NGC 2244 are presented. When only relative energy distributions are considered, thereby eliminating any dependence on reddening corrections or absolute energy calibrations, it is found that the ultraviolet energy distributions of the O stars have significantly cooler ultraviolet color temperatures than the cluster early B stars. The effect is not considered a property of the B stars because their observed continua can be well represented by model atmospheres and ultraviolet extinction characteristic of the local interstellar medium. The effect is thus thought to originate with the O star continua and can be due to either interstellar effects (the cluster O stars suffer additional extinction which has an anomalous wavelength dependence) or stellar effects (the physics incorporated into current O star model atmospheres is inadequate). It is noted that current data do not allow a definitive distinction to be made between these two alternatives, and the possible origins and consequences of each are considered.

The young open cluster NGC 3293 and its relation to CAR OB1 and the Carina Nebula complex

On the basis of visible evidence, NGC 3293 appears to be associated with a number of objects in the Carina Nebula complex. UBVRI photoelectric photometry and MK-spectral specifications are presented for a large number of stars in this cluster and its surroundings (Car OB1). Over 70 cluster members with spectral types earlier than B9 are identified. Star counts indicate that the expected number of members brighter than V = 18 is 297 plus or minus 9. The cluster appears to be situated just in front of a dense dust lane, which itself appears to be part of the dust complex emanating from the center of the Carina Nebula.

A UBV PHOTOMETRIC STUDY OF THE OPEN CLUSTER NGC 654.

ABSTRACT Photographic UBV magnitudes and colors are presented for 83 stars in the region of the young open cluster NGC 654, which Stone (1977) determined to have nonzero membership probabilities. It is noted that one-third of these stars lie outside the cluster nuclear region, indicating the presence of a stellar corona. Further, the coronal stars can be used to investigate the known variable reddening in a cluster region much larger than considered in previous photometric studies. It is found that over the extended region, the reddening varies from E(B-V) = 0.77 to 1.13 magnitudes with several stars having larger reddenings, and a variable-extinction analysis gives an averaged absorption ratio of R = 2.9 + or - 0.6 (s.e.) which is in good agreement with an earlier study by Turner (1976). In addition, attention is given to the cluster H-R diagram, a study of the nuclear and coronal cluster regions, and a comparison of the cluster luminosity function with the Initial Luminosity Function of Sandage (1957).

A study of the young open cluster NGC 6611

Photoelectric magnitudes and colours in theUBV system have been determined for 50 stars in NGC 6611. The reddening value varies across the cluster fromE(B-V)=0m58 toE(B-V)=1m21. The distance modulus to the cluster is estimated at 12m5±0m2. It is found that cluster stars are not of the same age. The cluster luminosity function is compared with the general and initial luminosity functions.

Study of the extremely young open cluster NGC 6530

Photoelectric magnitudes and colours in the UBV system have been determined for 101 stars in the field of NGC 6530. The interstellar reddening across the cluster varies from 0.25 to 0.48 mag, with an average value of 0.35 mag. The distance modulus to the cluster is estimated at 11.3 mag and age of 2x10 6 yr is ascribed. The cluster luminosity function is compared with the general luminosity function and the initial luminosity function. Star numbers 304 and 338 are in the early stages of their evolution while star numbers 171, 284 and 338 are probably variables.

Der offene sternhaufen NGC 2362

The very young open star cluster NGC 2362 was investigated by the strip method on charts of two photographs taken with the 1-m Schmidt telescope of the European Southern Observatory. Up to the limiting magnitudeMv*=5.m8 the cluster contains 100 stars and can be described by the Gaussian density law (6). Further results are: Mass\(\mathfrak{M}\) = 246\(\mathfrak{M}\)⊙, central mass densityρ0 = 43.1\(\mathfrak{M}\) = 246\(\mathfrak{M}\)⊙ pc-3 , radiusR≈2.6 pc, mean velocity of the stars\(\bar \upsilon\) = 0.64 km s−1.

OH Observations of the Open Cluster NGC 2264.

view Abstract Citations (14) References (5) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS OH Observations of the Open Cluster NGC 2264. Riegel, Kurt W. ; Crutcher, Richard M. Abstract The young open cluster NGC 2264 has been observed as a source of 1667- and 1665-MHz OH line emission. Further observations of the cluster and several nearby points in the sky, in the main lines and in the 1612- and 1720-MHz satellite lines, show that the OH emission is from interstellar dust clouds. Our data support the interpretation of thermal OH emission from dust clouds toward and near NGC 2264, and do not support Class lIb IR-OH or other discrete sources as the origin of the 18-cm OH emission. Publication: The Astrophysical Journal Pub Date: March 1972 DOI: 10.1086/180902 Bibcode: 1972ApJ...172L.107R full text sources ADS |

Stellar rings and galactic structure

Stellar rings are shell type prolate ellipsoidal stellar aggregates. The most important property is the constancy of the minor diameters which allows precise geometric distance determinations up to great distances. New photoelectric and photographic UBV-observations of two stellar rings confirm the reality and the diameter constancy of these objects. All A- and F-stars of a nearby ring in Aquila exhibit an UV-excess, similar to that observed in the very young open cluster NGC 2264.

An extremely red star in the region of the young open cluster NGC 6231

An extremely red star in the region of the young open cluster NGC 6231