Another cluster of red supergiants close to RSGC1

Negueruela, I.; González-Fernández, C.; Marco, A.; Clark, J. S.; Martínez-Núñez, Silvia

doi:10.1051/0004-6361/200913373

Cited by 71 publications

(113 citation statements)

References 41 publications

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“…We confirm that the selection of RSGs based on Q1 values adopted by Clark et al (2009), Negueruela et al (2010), and Negueruela et al (2011) (as remarked already in these works) excludes possible dust enshrouded RSG stars, and its strongly contaminated by AGBs (SRs and Miras). Selection of bona fide RSG stars solely based on the Q1 parameter is impossible.…”

Section: Selection Of Rsg Starssupporting

confidence: 87%

“…2MASS and GLIMPSE Messineo et al 2009). Five young massive stellar clusters (RSGC1, RSGC2, RSGC3, RSGC4, and RSGC5), extraordinarily rich in RSGs (14, 26, >8, >9, 7), have been located between 25 • and 30 • of longitude, at a distance of about 6 kpc probably at the near end-side of the Galactic Bar (Davies et al 2007;Figer et al 2006;Clark et al 2009;Negueruela et al 2010Negueruela et al , 2011. We restricted our analysis to a sample of 119 spectroscopically confirmed RSGs in clusters, because their association with a cluster confirms the luminosity class (Skiff 2010;Eggenberger et al 2002;Mermilliod et al 2008;Pierce et al 2000;Mengel & Tacconi-Garman 2007;Figer et al 1999;Messineo et al 2011Messineo et al , 2010Davies et al 2009a;Bernabei & Polcaro 2001;Caron et al 2003;Figer et al 2006;Davies et al 2008;Clark et al 2009;Negueruela et al 2010Negueruela et al , 2011.…”

Section: Red Supergiant Starsmentioning

confidence: 99%

“…The Q1 parameter was first introduced to photometrically select counterparts of high-mass X-ray binaries (Negueruela & Schurch 2007;Comerón & Pasquali 2005); it has been successfully used for searching clusters of RSGs (e.g. Figer et al 2006;Davies et al 2007;Clark et al 2009;Negueruela et al 2010Negueruela et al , 2011. Since stars with different spectral types have different intrinsic colors, they will also have a different value of Q1, as shown in Table 2 with intrinsic colors by Koornneef (1983).…”

Section: The Q1 Parametermentioning

confidence: 99%

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Near- and mid-infrared colors of evolved stars in the Galactic plane. TheQ1 andQ2 parameters

Messineo

Menten

Churchwell

et al. 2011

A&A

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Context. Mass-loss from evolved stars chemically enriches the interstellar medium (ISM). Stellar winds from massive stars and their explosions as supernovae shape the ISM and trigger star formation. Studying evolved stars is fundamental for understanding galaxy formation and evolution at any redshift. Aims. We aim to establish a photometric classification scheme for Galactic mass-losing evolved stars (e.g., WR, RSG, and AGB stars) with the goal of identifying new ones, and subsequently to use these samples as tracers of Galactic structure. Methods. We searched for counterparts of known Galactic WR, LBV, RSG, and O-rich AGB stars in the 2MASS, GLIMPSE, and MSX catalogs, and we analyzed their properties with near-and mid-infrared color-color diagrams. Results. We used the Q1 parameter, which is a measure of the deviation from the interstellar reddening vector in the J − H versus H−K s diagram, and we defined a new parameter, Q2, which is a measure of the deviation from the interstellar reddening vector in the Conclusions. The GLIMPSE catalog is a powerful tool for photometric classification of Galactic mass-losing evolved stars. Our new criteria will yield many new RSGs and WRs.

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Section: Selection Of Rsg Starssupporting

confidence: 87%

Section: Red Supergiant Starsmentioning

confidence: 99%

Section: The Q1 Parametermentioning

confidence: 99%

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Near- and mid-infrared colors of evolved stars in the Galactic plane. TheQ1 andQ2 parameters

Messineo

Menten

Churchwell

et al. 2011

A&A

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“…The catalogue of observed sources is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/578/A3 few years several massive and highly reddened clusters have been discovered in the inner Galaxy (Clark et al 2009b;Davies et al 2007Davies et al , 2008Davies et al , 2012Negueruela et al 2010). As their only observable components are the RSGs, these clusters are known as red supergiant clusters (RSGCs).…”

Section: Introductionmentioning

confidence: 99%

A new survey of cool supergiants in the Magellanic Clouds

González-Fernández

Dorda

Negueruela

et al. 2015

A&A

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Aims. In this study we conduct a pilot program aimed at the red supergiant population of the Magellanic Clouds. We intend to extend the current known sample to the unexplored low end of the brightness distribution of these stars, building a more representative dataset with which to extrapolate their behaviour to other Galactic and extra-galactic environments. Methods. We select candidates using only near infrared photometry, and with medium resolution multi-object spectroscopy, we perform spectral classification and derive their line-of-sight velocities, confirming the nature of the candidates and their membership in the clouds. Results. Around two hundred new red supergiants have been detected, hinting at a yet to be observed large population. Using nearand mid-infrared photometry we study the brightness distribution of these stars, the onset of mass-loss, and the effect of dust in their atmospheres. Based on this sample, new a priori classification criteria are investigated, combining mid-and near-infrared photometry to improve the observational efficiency of similar programs to this.

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“…The line of sight to the RSG clusters (RSGCs) passes through several Galactic arms and reaches an area of very high obscuration at a distance comparable to those of the clusters (Negueruela et al 2010). Stellar densities are extremely high at moderate K magnitudes, and cluster membership is difficult to assess for individual stars.…”

Section: Introductionmentioning

confidence: 99%

Red supergiants around the obscured open cluster Stephenson 2

Negueruela

Marco

González-Fernández

et al. 2012

A&A

Self Cite

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Context. Several clusters of red supergiants have been discovered in a small region of the Milky Way close to the base of the ScutumCrux Arm and the tip of the Long Bar. Population synthesis models indicate that they must be very massive to harbour so many supergiants. Amongst these clusters, Stephenson 2, with a core grouping of 26 red supergiants, is a strong candidate to be the most massive young cluster in the Galaxy. Aims. Stephenson 2 is located close to a region where a strong over-density of red supergiants had been found. We explore the actual cluster size and its possible connection to this over-density. Methods. Taking advantage of Virtual Observatory tools, we have performed a cross-match between the DENIS, USNO-B1 and 2MASS catalogues to identify candidate obscured luminous red stars around Stephenson 2, and in a control nearby region. More than 600 infrared bright stars fulfill our colour criteria, with the vast majority having a counterpart in the I band and >400 being sufficiently bright in I to allow observation with a 4-m class telescope. We observed a subsample of ∼250 stars, using the multi-object, wide-field, fibre spectrograph AF2 on the WHT telescope in La Palma, obtaining intermediate-resolution spectroscopy in the 7500-9000 Å range. We derived spectral types and luminosity classes for all these objects and measured their radial velocities. Results. Our targets turned out to be G and K supergiants, late (≥M4) M giants, and M-type bright giants (luminosity class II) and supergiants. We found ∼35 red supergiants with radial velocities similar to Stephenson 2 members, spread over the two areas surveyed. In addition, we found ∼40 red supergiants with radial velocities incompatible in principle with a physical association. Conclusions. Our results show that Stephenson 2 is not an isolated cluster, but part of a huge structure likely containing hundreds of red supergiants, with radial velocities compatible with the terminal velocity at this Galactic longitude (and a distance ∼6 kpc). In addition, we found evidence of several populations of massive stars at different distances along this line of sight.

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Another cluster of red supergiants close to RSGC1

Cited by 71 publications

References 41 publications

Near- and mid-infrared colors of evolved stars in the Galactic plane. TheQ1 andQ2 parameters

Near- and mid-infrared colors of evolved stars in the Galactic plane. TheQ1 andQ2 parameters

A new survey of cool supergiants in the Magellanic Clouds

Red supergiants around the obscured open cluster Stephenson 2

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