A search for late-type supergiants in the inner regions of the Milky Way

Comerón, F.; Torra, J.; Chiappini, Cristina; Figueras, F.; Ivanov, V. D.; Ribas, Salvador J.

doi:10.1051/0004-6361:20040312

Cited by 17 publications

(26 citation statements)

References 66 publications

(124 reference statements)

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“…The reference continuum was taken on both sides of the feature and interpolated, with the exception of the CO(λ = 2.293 µm) molecular band for which two reference continuum intervals on the shorter wavelength side were used for extrapolation, because there is no suitable continuum near the red edge of the feature. The positions and widths of the passbands used to measure the equivalent widths of the features and their chosen continuum reference points are the same as described in Comerón et al (2004). Uncertainties in the equivalent width measured in this way were estimated by repeating the measurements with different choices of the continuum level.…”

Section: Spectroscopymentioning

confidence: 99%

Red supergiants and the past of Cygnus OB2

Comerón

Djupvik

Schneider

et al. 2016

A&A

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Context. Red supergiants are the evolved descendants of massive stars with initial masses between 7 and 40 M . Their brightness makes them easily detectable in the near infrared, making them useful probes of star formation that occurred several tens of Myr ago. Aims. We investigate the past star formation history of Cygnus OB2, the nearest very massive OB association, using red supergiants as a probe. Our aim is to confirm the evidence, found by previous studies, that star formation in the Cygnus OB2 region started long before the latest burst that gave rise to the dense aggregate of early O-type stars that dominate the appearance of the association at present. Methods. Near-infrared star counts in the Cygnus region reveal moderate evidence for a peak in the areal density of bright, reddened stars approximately coincident with Cygnus OB2. A total of 11 sources are found within a circle of 1 • radius centered on the association, of which 4 are non-supergiants based on existing observations. Near-infrared spectroscopy is presented of the remaining seven candidates, including four that have been already classified as M supergiants in the literature. Results. We confirm the presence of seven red supergiants in the region and argue that they are probably physically associated with Cygnus OB2. Their location is roughly coincident with that of the older population identified by previous studies, supporting the scenario in which the main star formation activity in the association has been shifting toward higher Galactic longitudes with time. Their luminosities are compared with the predictions of evolutionary tracks with and without rotation to estimate the mass of their progenitors and ages. In this way, we confirm that massive star formation was already taking place in the area of Cygnus OB2 over 20 Myr ago, and we estimate that the star formation rate in the latest 6 Myr represents a six-fold increase over the massive star formation rate at the time when the progenitors of the current red supergiants were formed. Conclusions. The Cygnus OB2 association has a history of star formation extending into the past for at least about 20 Myr, probably dovetailing with the general history of star formation in the region that gave rise to other associations like the neighboring Cygnus OB9. The sustained massive star formation history also argues for a long lifetime of the giant molecular complex from which Cygnus OB2 formed, whose remnants constitute the present-day Cygnus X complex.

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Section: Spectroscopymentioning

confidence: 99%

Red supergiants and the past of Cygnus OB2

Comerón

Djupvik

Schneider

et al. 2016

A&A

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“…SiO and OH/IR stars show even redder H−K s colors, which are due to continuum absorption in H-band by water (e.g., Figs. 6 and 7 in Messineo et al 2005;Blum et al 2003;Frogel & Whitford 1987;Comerón et al 2004).…”

Section: H-k S Versus J-h Diagrammentioning

confidence: 99%

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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“…With a similar technique, Comerón et al (2004) identified 18 RSGs located in the Inner Galaxy. We observed nine of these RSGs, but maser emission was not detected.…”

Section: Trumpler 27mentioning

confidence: 99%

“…With our average rms noise of 0.23 Jy, we report the first unsuccessful searches toward targets in RSGC3, GLIMPSE9, MFD2008 and SGR 1900+14, as well as the isolated RSGs (Blum et al 2003;Comerón et al 2004) discussed in Sect. 6.11 (see Table 3).…”

Section: Clusters Without Sio Maser Detections -Summarymentioning

confidence: 99%

SiO maser emission from red supergiants across the Galaxy

Verheyen¹,

Messineo²,

Menten³

2012

A&A

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Aims. Red supergiants (RSGs) are among the most luminous of all stars, easily detectable in external galaxies, and may ideally serve as kinematic tracers of Galactic structure. Some RSGs are surrounded by circumstellar envelopes detectable by their dust and molecular and, in particular, maser emission. This study consists of a search for maser emission from silicon monoxide (SiO) toward a significant number of RSGs that are members of massive stellar clusters, many of which have only recently been discovered. Further, we aim to relate the occurrence of maser action to properties of the host stars. Methods. Using the IRAM 30 m telescope, we searched for maser emission in the J = 2−1 rotational transition within the first vibrationally excited state of SiO toward a sample of 88 RSGs. Results. With an average rms noise level of 0.25 Jy, we detected maser emission in 15% of the sample, toward most of the sources for the first time in this transition. The peak of the emission provides accurate radial velocities for the RSGs. The dependence of the detection rate on infrared colors supports a radiative pumping mechanism for the SiO masers.

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A search for late-type supergiants in the inner regions of the Milky Way

Cited by 17 publications

References 66 publications

Red supergiants and the past of Cygnus OB2

Red supergiants and the past of Cygnus OB2

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

SiO maser emission from red supergiants across the Galaxy

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