Stellar tracers of the Cygnus Arm

Negueruela, I.; Marco, A.

doi:10.1051/0004-6361:20030605

Cited by 34 publications

(32 citation statements)

References 44 publications

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“…For S166 Foster & MacWilliams (2006) give a spectrophotometric stellar distance of 2.57 ± 0.6 kpc for the exciting star BD+60 2607. S164 is excited by the B0.2III star (Negueruela & Marco 2003) ALS13056. Using SIMBAD we collect its photometry and calculate a distance of 2.87 ± 0.26 kpc.…”

Section: The Distance Of Star-forming Complexesmentioning

confidence: 99%

Revised distances of Northern HII regions

Russeil¹,

Adami²,

Georgelin³

2007

A&A

152

174

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Aims. Our aim is to determine the distance of outer Galaxy star-forming complexes in order to model the kinematic structure of our Galaxy. Methods. We searched for exciting star(s) of HII regions, with poor or unknown stellar distance, in the second and third galactic quadrants. We carried out spectroscopic and photometric (when necessary) observations in order to establish their spectral type and their U, B and V magnitudes. From these data, complemented with literature data, we determine the spectro-photometric distance of their associated complexes. Results. We (re)established the stellar distance of 23 star forming complexes. Reinvestigating the kinematics of the Perseus and Cygnus arms, we determined the velocity departures from circular rotation and we interpreted them as streaming motions in the spiral arms. Indeed, in addition to the Perseus arm where such departures were known for a long time, we added evidence for velocity deviations in the Cygnus arm. Most significant is that we found the opposite sign for these departures in the Perseus and Cygnus arms, which suggests that the co-rotation radius is located between these two arms at ∼13 kpc from the galactic center.

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Section: The Distance Of Star-forming Complexesmentioning

confidence: 99%

Revised distances of Northern HII regions

Russeil¹,

Adami²,

Georgelin³

2007

A&A

152

174

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“…The use of such models entails making several assumptions about unobserved conditions. Negueruela & Marco (2003) studied distant O-and B-type stars in the second Galactic quadrant, calculated their distances from their colors and spectral types, and found many to be tracers of the distant Cygnus arm. Melnik (2003) studied the local spiral structure of the Milky Way using the velocity field of nearby OB associations.…”

Section: Evaluation and Weightingmentioning

confidence: 99%

The Spiral Arms and Interarm Separation of the Milky Way: An Updated Statistical Study

2005

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Measurements of the spiral arms (their pitch angle, number, shape, and the interarm separation) in the Milky Way have been published in the period from 1980 to early 2005, using different methods that yielded slightly or widely differing values, depending on hidden or unknown biases. A meta-analysis would be useful for searching for trends among these individual studies. First, we find a convergence for three parameters: the pitch angle, the number of arms, and the shape of the arms. Second, we find a change for the interarm separation near the Sun, a decrease of about 25%; it is our determination of these parameters that evolves, not the actual physical arms. Third, we recalibrate a recent arm model to take account of that gradual change and compare it with the spread in each arm parameter.

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“…In view of this difficulty, we prefer to assume the distance derived from spectroscopic parallaxes using a standard R = 3.1 reddening law, i.e., a value d ∼ 5 kpc, as this is in line with the distances to tracers of the Outer Arm in the vicinity of NGC 1893 (Negueruela & Marco 2003).…”

Section: Distance Reddening and Extentmentioning

confidence: 99%

Pre-main-sequence stars in the young open cluster NGC 1893

Negueruela

Marco

Israel

et al. 2007

A&A

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Context. The open cluster NGC 1893 illuminating the H ii region IC 410 contains a moderately large population of O-type stars and is one of the youngest clusters observable in the optical range. It is suspected of harbouring a large population of pre-main-sequence (PMS) stars. Aims. We have probed the stellar population of NGC 1893 in an attempt to determine its size and extent. In particular, we look for signs of sequential star formation. Methods. We classify a large sample of cluster members with new intermediate-resolution spectroscopy. We used Hα slitless spectroscopy of the field to search for emission-line objects, identifying 18 emission-line PMS stars. We then combined existing optical photometry with the 2MASS JHK S photometry to detect stars with infrared excesses, finding close to 20 more PMS candidates.Results. While almost all stars earlier than B2 indicate standard reddening, all later cluster members show strong deviations from a standard reddening law, which we interpret in terms of infrared excess emission. Emission-line stars and IR-excess objects show the same spatial distribution, concentrating around two localised areas, the immediate vicinity of the pennant nebulae Sim 129 and Sim 130 and the area close to the cluster core where the rim of the molecular cloud associated with IC 410 is illuminated by the nearby O-type stars. In and around the emission nebula Sim 130, we find three Herbig Be stars with spectral types in the B1-4 range and several other fainter emission-line stars. We obtain a complete census of B-type stars by combining Strömgren, Johnson and 2MASS photometry and find a deficit of intermediate mass stars compared to massive stars. We observe a relatively extended halo of massive stars surrounding the cluster without an accompanying population of intermediate-mass stars. Conclusions. Stars in NGC 1893 show strong indications of being extremely young. The pennant nebula Sim 130 is an area of active massive star formation, displaying very good evidence of triggering by the presence of nearby massive stars. The overall picture of star formation in NGC 1893 suggests a very complex process.

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Stellar tracers of the Cygnus Arm

Cited by 34 publications

References 44 publications

Revised distances of Northern HII regions

Revised distances of Northern HII regions

The Spiral Arms and Interarm Separation of the Milky Way: An Updated Statistical Study

Pre-main-sequence stars in the young open cluster NGC 1893

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