Stellar X-ray Sources in the Rosette Nebula

Chen, W. P.; Chiang, P. S.; Li, J. Z.

doi:10.1088/1009-9271/4/2/153

Cited by 6 publications

(14 citation statements)

References 16 publications

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“…An inverse radius model [n(r) ¼ 3:5 þ 21:87/r, 2 ¼ 2:087] roughly describes the density distribution of the cluster. The stellar density profile drops steeply and merges with the background density distribution at a radius of around 20 0 , or 8.1 pc, at a distance of 1.5 kpc, which is commensurate with its extent both in the optical (Townsley et al 2003) and in the X-ray (Chen et al 2004;Berghofer & Christian 2002). Within this radius, the background distribution is subtracted and a net stellar population of 1901 AE 75 of the cluster is achieved, taking into account statistical errors in the background stellar distribution as calculated based on the control fields.…”

Section: Data Acquisition and Analysismentioning

confidence: 56%

Is the Emerging Massive Cluster NGC 2244 a Twin Cluster?

2005

ApJ

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We present in this paper the first near-infrared study of the young open cluster NGC 2244, which is well known for its partially embedded nature in the Rosette Nebula. Based on the spatially complete Two Micron All Sky Survey, the young OB cluster indicates apparent substructures. It is surprisingly resolved into a compact core that matches well the congregation of massive OB stars in the optical, a satellite cluster at a distance of 6.6 pc west of the center of NGC 2244 and probably a major stellar aggregate resembling an arc in structure right below the core. This infrared study provides various new updates on the nature of the young open cluster, including its central position, physical scale, and stellar population. A disk fraction of $20:5% AE 2:8% is achieved for its members with masses above 0.8 M . NGC 2244 is thus a unique example for the study of embedded clusters.

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Section: Data Acquisition and Analysismentioning

confidence: 56%

Is the Emerging Massive Cluster NGC 2244 a Twin Cluster?

2005

ApJ

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“…The spectral fit gives a plasma temperature of kT $ 1:6 keV with low absorption, log N H ¼ 20:6 cm ). An optical spectrum of the unresolved binary shows H in emission and Li i k6708 in absorption (Chen et al 2004), confirming its youth. We resolve the system as a close pair of ACIS sources (243 and 242).…”

Section: X-rays From Other Interesting Sourcesmentioning

confidence: 62%

“…No X-ray emission was found to be associated with these high-speed knots, but we detected point sources coincident with optical stars embedded in the nebulous region. ACIS source 678 (source 30 in Chen et al 2004) matches the position of HD 259210, a likely foreground star with spectral type A1 V.…”

Section: X-rays From Other Interesting Sourcesmentioning

confidence: 89%

“…Chen et al (2004) found an X-ray source in the nebulous region D with highspeed knots and identified two stars as counterparts within ROSAT positional errors. We examined our Chandra image with much higher resolution at all knot locations.…”

Section: X-rays From Other Interesting Sourcesmentioning

confidence: 98%

“…Berghöfer & Christian (2002) considered the integrated contribution from X-rayYemitting low-mass PMS stars in the cluster and concluded that apparently diffuse emission seen by ROSAT could be explained by unresolved point sources. Chen et al (2004) analyzed the same ROSAT data set and attributed the brightest X-ray sources to massive stars, active T Tauri stars, and foreground stars. Gregorio-Hetem et al (1998), studying a ROSAT observation of the RMC, reported faint X-ray point sources associated with T Tauri stars and Herbig Ae/Be (HAeBe) stars and X-ray ''hot spots'' from unresolved embedded low-mass star clusters.…”

Section: Introductionmentioning

confidence: 99%

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AChandraStudy of the Rosette Star‐forming Complex. I. The Stellar Population and Structure of the Young Open Cluster NGC 2244

Wang

Townsley

Feigelson

et al. 2008

ApJ

125

130

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We present the first high spatial resolution X-ray study of NGC 2244, the 2 Myr old stellar cluster in the Rosette Nebula, using Chandra. Over 900 X-ray sources are detected; 77% have optical or FLAMINGOS NIR stellar counterparts and are mostly previously uncataloged young cluster members. The X-rayYselected population is estimated to be nearly complete between 0.5 and 3 M . A number of further results emerge from our analysis: (1) The X-ray LF and the associated K-band LF indicate a normal Salpeter IMF for NGC 2244. This is inconsistent with the top-heavy IMF reported from earlier optical studies that lacked a good census o f <4 M stars. By comparing the NGC 2244 and Orion Nebula Cluster XLFs, we estimate a total population of $2000 stars in NGC 2244. (2) The spatial distribution of X-ray stars is strongly concentrated around the central O5 star, HD 46150. The other early O star, HD 46223, has few companions. The cluster's stellar radial density profile shows two distinctive structures: a power-law cusp around HD 46150 that extends to $0.7 pc, surrounded by an isothermal sphere extending out to 4 pc with core radius 1.2 pc. This double structure, combined with the absence of mass segregation, indicates that this 2 Myr old cluster is not in dynamical equilibrium. (3) The fraction of X-rayYselected cluster members with K-band excesses caused by inner protoplanetary disks is 6%, slightly lower than the 10% disk fraction estimated from the FLAMINGOS study based on the NIR-selected sample. (4) X-ray luminosities for 24 stars earlier than B4 confirm the long-standing log (L X /L bol ) $ À7 relation. The Rosette OB X-ray spectra are soft and consistent with the standard model of small-scale shocks in the inner wind of a single massive star.

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The influence of deceleration and internal structure on the braking index of pulsars: Simplest model for the star

et al. 2023

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Pulsars are rotating neutron stars whose electromagnetic radiation is observed to pulsate and, despite the extremely stable rates, the frequencies of the pulses decay with time, as quantified by the braking index (n). It is extremely difficult to obtain this index from observations due to different factors. Theoretically, in the canonical model for neutron stars, one finds n = 3, but observational data shows that n is less than three. In this work, the canonical model is modified, incorporating the influence of the deceleration of the neutron star. As the star's rotation decelerates, the deformation of the star due to the centrifugal force decreases thereby reducing its moment of inertia. Consequently, the star decelerates less, reducing the braking index. In this work, the star is modeled as a very hard, compressible spherical shell filled with neutrons and protons superfluid that do not interacts with the shell. Using this toy model as a first approach, the braking index is found as a function of rotation, yielding a theoretical braking index closer to the one derived from observational data.

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Stellar X-ray Sources in the Rosette Nebula

Cited by 6 publications

References 16 publications

Is the Emerging Massive Cluster NGC 2244 a Twin Cluster?

Is the Emerging Massive Cluster NGC 2244 a Twin Cluster?

AChandraStudy of the Rosette Star‐forming Complex. I. The Stellar Population and Structure of the Young Open Cluster NGC 2244

The influence of deceleration and internal structure on the braking index of pulsars: Simplest model for the star

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