A Massive Cluster of Red Supergiants at the Base of the Scutum‐Crux Arm

Davies, Ben; Figer, D. F.; Kudritzki, Rolf‐Peter; MacKenty, John; Najarro, F.; Herrero, A.

doi:10.1086/522224

Cited by 179 publications

(311 citation statements)

References 78 publications

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“…The equivalent widths (EWs) were measured from the continuum-normalized spectra using the iraf task splot. When the signal-to-noise ratio (S/N) was high enough, the luminosity class of the star was determined using the EW of the CO line and the Davies et al (2007) calibration. However, for spectroscopic targets displaying low S/N it was difficult to distinguish luminosity class I objects from their class III counterparts.…”

Section: Cluster Search and Methods Of Analysismentioning

confidence: 99%

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New galactic star clusters discovered in the VVV survey. Candidates projected on the inner disk and bulge

Borissova

Chené

Alegría

et al. 2014

A&A

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Context. VISTA Variables in the Vía Láctea (VVV) is one of six ESO Public Surveys using the 4 meter Visible and Infrared Survey Telescope for Astronomy (VISTA). The VVV survey covers the Milky Way bulge and an adjacent section of the disk, and one of the principal objectives is to search for new star clusters within previously unreachable obscured parts of the Galaxy. Aims. The primary motivation behind this work is to discover and analyze obscured star clusters in the direction of the inner Galactic disk and bulge. Methods. Regions of the inner disk and bulge covered by the VVV survey were visually inspected using composite JHK S color images to select new cluster candidates on the basis of apparent overdensities. DR1, DR2, CASU, and point spread function photometry of 10 × 10 arcmin fields centered on each candidate cluster were used to construct color-magnitude and color-color diagrams. Follow-up spectroscopy of the brightest members of several cluster candidates was obtained in order to clarify their nature. Results. We report the discovery of 58 new infrared cluster candidates. Fundamental parameters such as age, distance, and metallicity were determined for 20 of the most populous clusters.

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Section: Cluster Search and Methods Of Analysismentioning

confidence: 99%

“…4). Based on the spectral type vs. EW(CO) relation established by Davies et al (2007), the stars could be G9-K2 supergiants. The spectra of the fifth star Obj 5 is different, however, and exhibits shallow and irregularly shaped CO and He I absorption lines (at λ 2.05 μm).…”

Section: Fundamental Parameters For Populous Cluster Candidatesmentioning

confidence: 99%

New galactic star clusters discovered in the VVV survey. Candidates projected on the inner disk and bulge

Borissova

Chené

Alegría

et al. 2014

A&A

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“…and Borissova et al (2003) reported lists of cluster candidates identified as number-density peaks in the 2mass Point Source Catalog (PSC; Cutri et al 2003). These studies were soon followed by others (i.e., Froebrich et al 2007aFroebrich et al , 2007bFroebrich et al , 2008Mercer et al 2005;Davies et al 2007), who found additional cluster candidates.…”

Section: Introductionmentioning

confidence: 96%

“…We optimized IAUS266. IR surveys of Galactic star clusters 205 our criteria for clusters containing red supergiants (RSGs), because many of the known supermassive Milky Way clusters host this type of star (i.e., Davies et al 2007). The criteria can easily be modified to favor clusters containing other stellar types.…”

Section: Introductionmentioning

confidence: 99%

Infrared surveys of Galactic star clusters

Ivanov¹,

Messineo²,

Zhu³

et al. 2009

Proc. IAU

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Abstract. Many attempts have been made to carry out a complete observational census of Milky Way star clusters based on recent near-and mid-infrared surveys. However, more clusters are still being discovered, indicating that existing catalogs are incomplete. We attempt to estimate the total number of supermassive (SM; M cl 10 4 M ) clusters in the Galaxy, and to improve the yield from the automated cluster searches. Assuming that the 'local' census of SM clusters is complete, and that their surface density accross the disk follows that of the stars, we predict that the Milky Way contains 81 ± 21 SM clusters. We apply a cluster-detection algorithm to the 2mass Point Source Catalog after a preliminary color and/or magnitude selection of the point sources to improves the surface-density cluster-to-field contrast. Our algorithm identified 94 new candidates, and re-identified 34 known clusters. During the visual inspection, we detected an additional 41 new candidates, and re-identified 32 known objects. Preliminary characterization suggests that the new list may contain red-supergiant, open and globular clusters.

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“…While simple stellar population models predict that the colours of evolving stellar clusters do not vary strongly after 8 − 10 Myr, the near-IR offers the opportunity to pick out highly embedded clusters, both through their stellar continuum as well as their nebular line emission (e.g., Brγ). For example, mid-IR surveys such as the Spitzer Glimpse Survey (Churchwell et al 2009) allowed the discovery of two (and subsequently many more) highly extincted massive young clusters located near the end of the Galactic bar (Figer et al 2006;Davies et al 2007). …”

Section: Introductionmentioning

confidence: 99%

The effect of spatial resolution on optical and near-IR studies of stellar clusters: implications for the origin of the red excess

Bastian

Adamo

Schirmer

et al. 2014

Monthly Notices of the Royal Astronomical Society

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Recent ground based near-IR studies of stellar clusters in nearby galaxies have suggested that young clusters remain embedded for 7 − 10 Myr in their progenitor molecular cloud, in conflict with optical based studies which find that clusters are exposed after 1 − 3 Myr. Here, we investigate the role that spatial resolution plays in this apparent conflict. We use a recent catalogue of young (< 10 Myr) massive (> 5000 M ⊙ ) clusters in the nearby spiral galaxy, M83, along with Hubble Space Telescope (HST) imaging in the optical and near-IR, and ground based near-IR imaging, to see how the colours (and hence estimated properties such as age and extinction) are affected by the aperture size employed, in order to simulate studies of differing resolution. We find that the near-IR is heavily affected by the resolution, and when aperture sizes > 40 pc are used, all young/blue clusters move red-ward in colour space, which results in their appearance as heavily extincted clusters. However, this is due to contamination from nearby sources and nebular emission, and is not an extinction effect. Optical colours are much less affected by resolution. Due to the larger affect of contamination in the near-IR, we find that, in some cases, clusters will appear to show near-IR excess when large (> 20 pc) apertures are used. Our results explain why few young (< 6 Myr), low extinction (A V < 1 mag) clusters have been found in recent ground based near-IR studies of cluster populations, while many such clusters have been found in higher resolution HST based studies. Additionally, resolution effects appear to (at least partially) explain the origin of the near-IR excess that has been found in a number of extragalactic YMCs.

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A Massive Cluster of Red Supergiants at the Base of the Scutum‐Crux Arm

Cited by 179 publications

References 78 publications

New galactic star clusters discovered in the VVV survey. Candidates projected on the inner disk and bulge

New galactic star clusters discovered in the VVV survey. Candidates projected on the inner disk and bulge

Infrared surveys of Galactic star clusters

The effect of spatial resolution on optical and near-IR studies of stellar clusters: implications for the origin of the red excess

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