The Initial Mass Function and Young Brown Dwarf Candidates in NGC 2264. Iii. Photometric Data

Sung, Hwankyung; Bessell, M. S.; Chun, Moo-Young; Karimov, R.; Ibrahimov, M.

doi:10.1088/0004-6256/135/2/441

Cited by 63 publications

(192 citation statements)

References 51 publications

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“…The star W2320 (LkHα 4) was selected as the member of the cluster from Hα photometry (Sung et al 2008). The spectrum of the star shows a moderately strong Hα emission line with a blueshifted absorption component (Figure 11).…”

Section: Discussion On the Li-deficient Starsmentioning

confidence: 99%

“…c Chandra X-ray source catalog from Sung et al (2004). d XMM Newton X-ray source catalog from Dahm et al (2007) e Probable Hα emission star from Sung et al (2008).…”

Section: Discussionmentioning

confidence: 99%

“…Since low-mass active PMS stars, in general, show a broad, strong Hα emission line, it is sometimes difficult to directly distinguish the Hα emission line of the nebula from that of the target spectra. However, the [N II] (Sung et al 1997;Park et al 2000;Sung et al 2004Sung et al , 2008Sung et al , 2009) (left) and their age distribution (right). The stars observed for this study are marked by bold red dots.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…For this reason, the spectra of the 10 faintest stars were obtained with very low signal levels. In addition, the Li I λ6708 line was not detected in the spectrum of star S2587 (6300 K-star identification used in Sung et al 2008) due to the low signal-tonoise ratio although it is a relatively bright star (V= 11.10 mag). We could not find the Li I absorption line in the spectra of 19 bright PMS stars.…”

Section: Measurements Of Equivalent Widthsmentioning

confidence: 99%

“…According to Fűrész et al (2006) and Sung et al (2009), NGC 2264 is comprised of at least three subclusters-the S Mon, Spokes, and Cone nebula regions as shown in Figure 9. In addition, a low stellar density region (halo) surrounds these subclusters (Sung et al 2008). The largest subcluster S Mon contains not only the high-mass multiple system S Mon (O7V + early B + ?- Sota et al 2011) but also a large number of Class II objects.…”

Section: Age Spread and Cluster Formation Timescalementioning

confidence: 99%

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A Constraint on the Formation Timescale of the Young Open Cluster NGC 2264: Lithium Abundance of Pre-Main Sequence Stars

Lim

Sung

Kim

et al. 2016

ApJ

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The timescale of cluster formation is an essential parameter in order to understand the formation process of star clusters. Pre-main sequence (PMS) stars in nearby young open clusters reveal a large spread in brightness. If the spread were considered to be a result of a real spread in age, the corresponding cluster formation timescale would be about 5-20 Myr. Hence it could be interpreted that star formation in an open cluster is prolonged for up to a few tens of Myr. However, difficulties in reddening correction, observational errors, and systematic uncertainties introduced by imperfect evolutionary models for PMS stars can result in an artificial age spread. Alternatively, we can utilize Li abundance as a relative age indicator of PMS star to determine the cluster formation timescale. The optical spectra of 134 PMS stars in NGC 2264 have been obtained with MMT/Hectochelle. The equivalent widths have been measured for 86 PMS stars with a detectable Li line (). Li abundance under the condition of local thermodynamic equilibrium (LTE) was derived using the conventional curve of growth method. After correction for non-LTE effects, we find that the initial Li abundance of NGC 2264 is. From the distribution of the Li abundances, the underlying age spread of the visible PMS stars is estimated to be about 3-4 Myr and this, together with the presence of embedded populations in NGC 2264, suggests that the cluster formed on a timescale shorter than 5 Myr.

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Section: Discussion On the Li-deficient Starsmentioning

confidence: 99%

“…c Chandra X-ray source catalog from Sung et al (2004). d XMM Newton X-ray source catalog from Dahm et al (2007) e Probable Hα emission star from Sung et al (2008).…”

Section: Discussionmentioning

confidence: 99%

Section: Observations and Data Reductionmentioning

confidence: 99%

Section: Measurements Of Equivalent Widthsmentioning

confidence: 99%

Section: Age Spread and Cluster Formation Timescalementioning

confidence: 99%

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A Constraint on the Formation Timescale of the Young Open Cluster NGC 2264: Lithium Abundance of Pre-Main Sequence Stars

Lim

Sung

Kim

et al. 2016

ApJ

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Correlated optical and X-ray variability in CTTS

Flaccomio

Micela

Favata

et al. 2010

A&A

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Aims. Optical and X-ray emission from classical T Tauri stars (CTTSs) has long been known to be highly variable. Our long, uninterrupted optical observation of the NGC 2264 region with CoRoT allows the optical variability in CTTS to be studied with unprecedented accuracy and time coverage. Two short Chandra observations obtained during the CoRoT pointing with a separation of 16 days allow us to study whether there is a correlation between optical and X-ray variability on this timescale, thus probing the physical mechanisms driving the variability in both bands. Methods. We have computed the optical and X-ray fractional variability between the two 30 ks duration windows covered by both the Chandra and CoRoT observations, for a sample of classical and weak line T Tauri stars (WTTSs) in NGC 2264. A scatter plot clearly shows that the variability of CTTSs in the optical and soft X-ray (0.5-1.5 keV) bands is correlated, while no correlation is apparent in the hard (1.5-8.0 keV) band. Also, no correlation in either band is present for WTTSs. Results. We show that the correlation between soft X-ray and optical variability of CTTSs can be naturally explained in terms of time-variable shading (absorption) from circumstellar material orbiting the star, in a scenario rather similar to the one invoked to explain the observed phenomenology in the CTTS AA Tau. The slope of the observed correlation implies (in the hypothesis of homogeneous shading) a significant dust depletion in the circumstellar material (with a gas-to-dust ratio approximately 5 times lower than the standard value for interstellar material).

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Exploring the origin of magnetic fields in massive stars

Hubrig

Schöller

Ilyin

et al. 2013

A&A

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Context. Theories on the origin of magnetic fields in massive stars remain poorly developed, because the properties of their magnetic field as function of stellar parameters could not yet be investigated. Additional observations are of utmost importance to constrain the conditions that are conducive to magnetic fields and to determine first trends about their occurrence rate and field strength distribution. Aims. To investigate whether magnetic fields in massive stars are ubiquitous or appear only in stars with a specific spectral classification, certain ages, or in a special environment, we acquired 67 new spectropolarimetric observations for 30 massive stars. Among the observed sample, roughly one third of the stars are probable members of clusters at different ages, whereas the remaining stars are field stars not known to belong to any cluster or association. Methods. Spectropolarimetric observations were obtained during four different nights using the low-resolution spectropolarimetric mode of FOcal Reducer low dispersion Spectrograph (FORS 2) mounted on the 8-m Antu telescope of the VLT. Furthermore, we present a number of follow-up observations carried out with the high-resolution spectropolarimeters SOFIN mounted at the Nordic Optical Telescope (NOT) and HARPS mounted at the ESO 3.6 m between 2008 and 2011. To assess the membership in open clusters and associations, we used astrometric catalogues with the highest quality kinematic and photometric data currently available. Results. The presence of a magnetic field is confirmed in nine stars previously observed with FORS

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The Initial Mass Function and Young Brown Dwarf Candidates in NGC 2264. Iii. Photometric Data

Cited by 63 publications

References 51 publications

A Constraint on the Formation Timescale of the Young Open Cluster NGC 2264: Lithium Abundance of Pre-Main Sequence Stars

A Constraint on the Formation Timescale of the Young Open Cluster NGC 2264: Lithium Abundance of Pre-Main Sequence Stars

Correlated optical and X-ray variability in CTTS

Exploring the origin of magnetic fields in massive stars

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