The massive star initial mass function of the Arches cluster

Espinoza, Paula; Selman, F.; Melnick, J.

doi:10.1051/0004-6361/20078597

Cited by 149 publications

(252 citation statements)

References 43 publications

(78 reference statements)

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“…It has also often been claimed that some (very) massive star-forming regions have a truncated IMF, i.e., contain much smaller numbers of low-mass stars than expected from the field IMF. However, most of the more recent and sensitive studies of massive star-forming regions (see, e.g., Liu et al 2009;Espinoza et al 2009) find the numbers of low-mass stars in agreement with the expectation from the "normal" field star IMF. Preibisch et al (2011c) confirm these results for the Carina nebula and support the assumption of a universal IMF (at least in our Galaxy).…”

Section: Initial Mass Functionsupporting

confidence: 54%

Investigation of the stellar content in the western part of the Carina nebula

Kumar¹,

Sharma²,

Manfroid³

et al. 2014

A&A

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Context. The low obscuration and proximity of the Carina nebula make it an ideal place to study the ongoing star formation process and impact of massive stars on low-mass stars in their surroundings. Aims. To investigate this process, we generated a new catalog of the pre-main-sequence stars in the Carina west (CrW) region and studied their nature and spatial distribution. We also determined various parameters (reddening, reddening law, age, mass), which are used further to estimate the initial mass function and K-band luminosity function for the region under study. Methods. We obtained deep UBVRI Hα photometric data of the field situated to the west of the main Carina nebula and centered on WR 22. Medium-resolution optical spectroscopy of a subsample of X-ray selected objects along with archival data sets from Chandra, XMM-Newton and 2MASS surveys were used for the present study. Different sets of color-color and color-magnitude diagrams are used to determine reddening for the region and to identify young stellar objects (YSOs) and estimate their age and mass. Results. Our spectroscopic results indicate that the majority of the X-ray sources are late spectral type stars. The region shows a large amount of differential reddening with minimum and maximum values of E(B − V) as 0.25 and 1.1 mag, respectively. Our analysis reveals that the total-to-selective absorption ratio R V is ∼3.7 ± 0.1, suggesting an abnormal grain size in the observed region. We identified 467 YSOs and studied their characteristics. The ages and masses of the 241 optically identified YSOs range from ∼0.1 to 10 Myr and ∼0.3 to 4.8 M , respectively. However, the majority of them are younger than 1 Myr and have masses below 2 M . The high mass star WR 22 does not seem to have contributed to the formation of YSOs in the CrW region. The initial mass function slope, Γ, in this region is found to be −1.13 ± 0.20 in the mass range of 0.5 < M/M < 4.8. The K-band luminosity function slope (α) is also estimated as 0.31 ± 0.01. We also performed minimum spanning tree analysis of the YSOs in this region, which reveals that there are at least ten YSO cores associated with the molecular cloud, and that leads to an average core radius of 0.43 pc and a median branch length of 0.28 pc.

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Section: Initial Mass Functionsupporting

confidence: 54%

Investigation of the stellar content in the western part of the Carina nebula

Kumar¹,

Sharma²,

Manfroid³

et al. 2014

A&A

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“…The K s photometry of the Arches cluster was calibrated with respect to Espinoza et al (2009). Fields 3-5 were calibrated from overlap areas with the central field and calibrations were crosschecked in each overlap region.…”

Section: Photometry and Astrometrymentioning

confidence: 99%

Circumstellar discs in Galactic centre clusters: Disc-bearing B-type stars in the Quintuplet and Arches clusters

Stolte

Hussmann

Olczak

et al. 2015

A&A

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We investigate the circumstellar disc fraction as determined from L-band excess observations of the young, massive Arches and Quintuplet clusters residing in the central molecular zone of the Milky Way. The Quintuplet cluster was searched for L-band excess sources for the first time. We find a total of 26 excess sources in the Quintuplet cluster, and 21 sources with L-band excesses in the Arches cluster, of which 13 are new detections. With the aid of proper motion membership samples, the disc fraction of the Quintuplet cluster could be derived for the first time to be 4.0 ± 0.7%. There is no evidence for a radially varying disc fraction in this cluster. In the case of the Arches cluster, a disc fraction of 9.2 ± 1.2% approximately out to the cluster's predicted tidal radius, r < 1.5 pc, is observed. This excess fraction is consistent with our previously found disc fraction in the cluster in the radial range 0.3 < r < 0.8 pc. In both clusters, the host star mass range covers late A-to early B-type stars, 2 < M < 15 M , as derived from J-band photospheric magnitudes. We discuss the unexpected finding of dusty circumstellar discs in these UV intense environments in the context of primordial disc survival and formation scenarios of secondary discs. We consider the possibility that the L-band excess sources in the Arches and Quintuplet clusters could be the high-mass counterparts to T Tauri pre-transitional discs. As such a scenario requires a long pre-transitional disc lifetime in a UV intense environment, we suggest that mass transfer discs in binary systems are a likely formation mechanism for the B-star discs observed in these starburst clusters.

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“…Therefore we adopt an initial half-mass radius of 0.2 pc and chose the SFE to be 70%. For the mass distribution in the cluster we choose a modified King profile for the stars and a corresponding Plummer profile for the gas, because this reflects the situation in observed clusters very well (Espinoza et al 2009;Steinhausen 2013). No primordial binaries were included, as this would have significantly complicated the determination of the effect of a fly-by on the system.…”

Section: Methodsmentioning

confidence: 99%

Did a stellar fly-by shape the planetary system around Pr 0211 in the cluster M44?

Pfalzner¹,

Bhandare²,

Vincke³

2018

A&A

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Aims. Out of the ∼ 3000 exoplanets detected so far, only fourteen planets are members of open clusters: among them an exoplanet system around Pr 0211 in the cluster M44 which consists of at least two planets with the outer planet moving on a highly eccentric orbit at 5.5 AU. One hypothesis is that a close fly-by of a neighbouring star was responsible for the eccentric orbit. We test this hypothesis. Methods. First we determine the type of fly-by that would lead to the observed parameters and then use this result to determine the history of such fly-bys in simulations of the early dynamics in an M44-like environment. Results. We find that although very close fly-bys are required to obtain the observed properties of Pr 0211c, such fly-bys are relatively common due to the high stellar density and longevity of the cluster. About 10% of stars actually experience a fly-by that would lead to such a small system-size as observed for Pr0211 or even smaller. Such close fly-bys are most frequent during the first 1-2 Myr after cluster formation, corresponding to a cluster age ≤ 3 Myr. It is unclear whether planets generally form on such short timescales. However, afterwards the close fly-by rate is still 0.2-0.5 Myr −1 , which means extrapolating this to the age of M44 12%-20% of stars would experience such close fly-bys over this timespan. Conclusions. Our simulations show that the fly-by scenario is a realistic option for the formation of eccentricity orbits of the planets in M44. The occurance of such events is relatively high leading to the expectation that similar systems are likely common in open clusters in general.

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The massive star initial mass function of the Arches cluster

Cited by 149 publications

References 43 publications

Investigation of the stellar content in the western part of the Carina nebula

Investigation of the stellar content in the western part of the Carina nebula

Circumstellar discs in Galactic centre clusters: Disc-bearing B-type stars in the Quintuplet and Arches clusters

Did a stellar fly-by shape the planetary system around Pr 0211 in the cluster M44?

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