1,742,707 research outputs found
Age spread and sequential star formation in the young cluster NGC 2264
Get PDFWe investigate the structure and star formation history of the NGC 2264 cluster (3 Myr). We combine spectroscopic T_eff with multi-color photometry to derive homogeneous extinction and stellar parameters for 655 cluster members (M_star = 0.2-1.8 M_☉). We infer an intrinsic age spread of ∼4 Myr across the cluster. NGC 2264 members were born in the course of sequential star formation activity, which still continues in the most embedded regions of the cluster. We find evidence for photoevaporation effects driven by OB stars in the region that locally impact the timescales for disk evolution within the cluster
Constraints on star formation in NGC 2264
Get PDFWe quantify the spatial distribution of stars for two subclusters centred around the massive/intermediate mass stars S Mon and IRS 1/2 in the NGC 2264 star-forming region. We find that both subclusters are have neither a substructured, nor a centrally concentrated distribution according to the Q-parameter. Neither subcluster displays mass segregation according to the ΛMSR ratio, but the most massive stars in IRS 1/2 have higher relative surface densities according to the ΣLDR ratio. We then compare these quantities to the results of N-body simulations to constrain the initial conditions of NGC 2264, which are consistent with having been dense (ρ~∼104 M⊙ pc−3), highly substructured and subvirial. These initial conditions were also derived from a separate analysis of the runaway and walkaway stars in the region, and indicate that star-forming regions within 1 kpc of the Sun likely have a broad range of initial stellar densities. In the case of NGC 2264, its initial stellar density could have been high enough to cause the destruction or truncation of protoplanetary discs and fledgling planetary systems due to dynamical encounters between stars in the early stages of its evolution
Killeen, Kenneth F, W-2264
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/397148Surname: KILLEEN. Given Name(s) or Initials: KENNETH F. Military Service Number or Last Known Location: W-2264. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 28662.234392
Item: [2016.0049.29441] "Killeen, Kenneth F, W-2264
The Gaia-ESO Survey and CSI 2264: Substructures, disks, and sequential star formation in the young open cluster NGC 2264
Get PDFContext. Reconstructing the structure and history of young clusters is pivotal to understanding the mechanisms and timescales of early stellar evolution and planet formation. Recent studies suggest that star clusters often exhibit a hierarchical structure, possibly resulting from several star formation episodes occurring sequentially rather than a monolithic cloud collapse.Aims. We aim to explore the structure of the open cluster and star-forming region NGC 2264 (~3 Myr), which is one of the youngest, richest and most accessible star clusters in the local spiral arm of our Galaxy; we link the spatial distribution of cluster members to other stellar properties such as age and evolutionary stage to probe the star formation history within the region.Methods. We combined spectroscopic data obtained as part of the Gaia-ESO Survey (GES) with multi-wavelength photometric data from the Coordinated Synoptic Investigation of NGC 2264 (CSI 2264) campaign. We examined a sample of 655 cluster members, with masses between 0.2 and 1.8 M? and including both disk-bearing and disk-free young stars. We used Teff estimates from GES and g,r,i photometry from CSI 2264 to derive individual extinction and stellar parameters.Results. We find a significant age spread of 4–5 Myr among cluster members. Disk-bearing objects are statistically associated with younger isochronal ages than disk-free sources. The cluster has a hierarchical structure, with two main blocks along its latitudinal extension. The northern half develops around the O-type binary star S Mon; the southern half, close to the tip of the Cone Nebula, contains the most embedded regions of NGC 2264, populated mainly by objects with disks and ongoing accretion. The median ages of objects at different locations within the cluster, and the spatial distribution of disked and non-disked sources, suggest that star formation began in the north of the cluster, over 5 Myr ago, and was ignited in its southern region a few Myr later. Star formation is likely still ongoing in the most embedded regions of the cluster, while the outer regions host a widespread population of more evolved objects; these may be the result of an earlier star formation episode followed by outward migration on timescales of a few Myr. We find a detectable lag between the typical age of disk-bearing objects and that of accreting objects in the inner regions of NGC 2264: the first tend to be older than the second, but younger than disk-free sources at similar locations within the cluster. This supports earlier findings that the characteristic timescales of disk accretion are shorter than those of disk dispersal, and smaller than the average age of NGC 2264 (i.e., ?3 Myr). At the same time, we note that disks in the north of the cluster tend to be shorter-lived (~2.5 Myr) than elsewhere; this may reflect the impact of massive stars within the region (notably S Mon), that trigger rapid disk dispersal.Conclusions. Our results, consistent with earlier studies on NGC 2264 and other young clusters, support the idea of a star formation process that takes place sequentially over a prolonged span in a given region. A complete understanding of the dynamics of formation and evolution of star clusters requires accurate astrometric and kinematic characterization of its population; significant advance in this field is foreseen in the upcoming years thanks to the ongoing Gaia mission, coupled with extensive ground-based surveys like GES
The Distance to NGC 2264
Get PDFWe determine the distance to the open cluster NGC 2264 using a statistical analysis of cluster member inclinations. We derive distance-dependent values of sin i (where i is the inclination angle) for 97 stars in NGC 2264 from the rotation periods, luminosities, effective temperatures, and projected equatorial rotation velocities, v sin i, measured for these stars. We have measured 96 of the vsin i values in our sample by analyzing high-resolution spectra with a cross-correlation technique. We model the observed distribution of sin i for the cluster by assuming that member stars have random axial orientations and by adopting prescriptions for the measurement errors in our sample. By adjusting the distance assumed in the observed sin i distribution until it matches the modeled distribution, we obtain a best-fit distance for the cluster. We find the data to be consistent with a distance to NGC 2264 of 913 pc. Quantitative tests of our analysis reveal uncertainties of 40 and 110 pc due to sampling and systematic effects, respectively. This distance estimate suggests a revised age for the cluster of ~1.5 Myr, although more detailed investigations of the full cluster membership are required to draw strong conclusions
Identifying primordial substructure in NGC 2264
No full textWe present new Spitzer Space Telescope observations of the young cluster NGC 2264. Observations at 24 μm with the Multiband Imaging Photometer have enabled us to identify the most highly embedded and youngest objects in NGC 2264. This Letter reports on one particular region of NGC 2264 where bright 24 μm sources are spatially configured in curious linear structures with quasi-uniform separations. The majority of these sources (∼60%) are found to be protostellar in nature, with Class I spectral energy distributions. Comparison of their spatial distribution with submillimeter data from Wolf-Chase et al. and millimeter data from Peretto et al. shows a close correlation between the dust filaments and the linear spatial configurations of the protostars, indicating that star formation is occurring primarily within dense, dusty filaments. Finally, the quasi-uniform separations of the protostars are found to be comparable in magnitude to the expected Jeans length, suggesting thermal fragmentation of the dense filamentary material.</p
Union Pacific (UP) 2264 & 5518
No full textA photograph postcard showing Union Pacific (UP) 2264, 2-8-2, and 5518, 2-10-2, on westbound freight extra, climbing Cajon Pass, near Summit, CA, 42 cars, 25 mph
observations of the young open cluster NGC 2264
No full textContext. Photometric time series obtained from space are one of the best ways to study pulsations in pre-main sequence (PMS) stars, especially as the corresponding amplitudes are at the millimagnitude level or below. We present high-precision time-series photometry of stars in the field of NGC 2264 obtained with the MOST (Microvariability & Oscillations of STars) satellite.
Aims. A search for pulsating A and F type members of NGC 2264 with ultra-precise MOST photometry was conducted.
Methods. 68 stars in the field of NGC 2264 were observed simultaneously with the MOST satellite, 34 of which were previously identified as potential targets to search for PMS pulsation. The routines Si
Block Card 2264 Westbrook Drive
No full textThis image was produced by the Auditor's Office in Lucas County, Ohio for tax assessment purposes. Associated dates are approximate. Descriptive terms related to this photograph include: dwelling | 2264 Westbrook Drive (Toledo, Ohio) | Colonial Revival Style | DeVeaux (Toledo, Ohio) | Extension of Mellwood (Toledo, Ohio
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