Resolving the kinematic distance ambiguity of southern massive young stellar object candidates

Busfield, A. L.; Purcell, Cormac; Hoare, M. G.; Lumsden, S. L.; Moore, T. J. T.; Oudmaijer, R. D.

doi:10.1111/j.1365-2966.2005.09909.x

Cited by 57 publications

(72 citation statements)

References 20 publications

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“…As the previous one, this method still relies on the calculation of kinematic distances, which requires a good knowledge of the rotation curve of the Galaxy. Recently, Busfield et al (2006) used this method to successfully determine the distances of a number of massive young stellar object candidates in the fourth quadrant of our Galaxy. The authors succeeded to resolve the distance ambiguity for 80% of their targets, the main limitations being the coarse spatial resolution of the archival Hi data as well as the inability to apply the method for sources at galactic longitudes < |15 • |.…”

Section: Modelling the Maser Distribution And Luminosity Functionmentioning

confidence: 99%

A general catalogue of 6.7 GHz methanol masers

Pestalozzi

Chrysostomou

Collett

et al. 2006

A&A

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Context. Methanol masers at 6.7 GHz are recognised markers of high-mass star formation regions. The study of their distribution in the Galaxy gives important insights into the star formation activity of the Milky Way. We present a statistical analysis on the General Catalogue of 6.7 GHz methanol masers in the Galaxy with the aim of extracting global properties of the masers. Aims. We provide constraints on the luminosity function of 6.7 GHz methanol masers and on their total number in the Galaxy. Methods. We model the spatial distribution of the masers in the Milky Way by using their distribution in galactocentric distance which is unambiguous once a rotation curve for the Galaxy is assumed. This is the starting point for determining the luminosity function of the masers.Results. The luminosity function of 6.7 GHz methanol masers is modelled as a power-law with sharp cutoffs and having an index lying between −1.5 and −2. We also predict the number of detections of methanol masers assuming different sensitivity limits in the observations.

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Section: Modelling the Maser Distribution And Luminosity Functionmentioning

confidence: 99%

A general catalogue of 6.7 GHz methanol masers

Pestalozzi

Chrysostomou

Collett

et al. 2006

A&A

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“…Other sources from the radial velocity literature that we employ include Busfield et al (2006), who use H I self-absorption data while Sewilo et al (2004) use H 2 CO absorption data. Both Fish et al (2003) and Kolpak et al (2003) provide H I line absorption (measured against H II continuum background).…”

Section: Radial Velocities and Distancesmentioning

confidence: 99%

Milky Way Star-Forming Complexes and the Turbulent Motion of the Galaxy's Molecular Gas

Lee

Murray

Rahman

2012

ApJ

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We analyze Spitzer GLIMPSE, MSX, and WMAP images of the Milky Way to identify 8 micron and free-free sources in the Galaxy. Seventy-two of the eighty-eight WMAP sources have coverage in the GLIMPSE and MSX surveys suitable for identifying massive star forming complexes (SFC). We measure the ionizing luminosity functions of the SFCs and study their role in the turbulent motion of the Galaxy's molecular gas. We find a total Galactic free-free flux f ν = 46177.6 Jy; the 72 WMAP sources with full 8 micron coverage account for 34263.5 Jy (∼ 75%), with both measurements made at ν=94GHz (W band). We find a total of 280 SFCs, of which 168 have unique kinematic distances and free-free luminosities. We use a simple model for the radial distribution of star formation to estimate the free-free and ionizing luminosity for the sources lacking distance determinations. The total dust-corrected ionizing luminosity is Q = 2.9 ± 0.5 x 10 53 photons s −1 , which implies a galactic star formation rate oḟ M * = 1.2 ± 0.2 M ⊙ yr −1 . We present the (ionizing) luminosity function of the SFCs, and show that 24 sources emit half the ionizing luminosity of the Galaxy. The SFCs appear as bubbles in GLIMPSE or MSX images; the radial velocities associated with the bubble walls allow us to infer the expansion velocity of the bubbles. We calculate the kinetic luminosity of the bubble expansion and compare it to the turbulent luminosity of the inner molecular disk. SFCs emitting 80% of the total galactic free-free luminosity produce a kinetic luminosity equal to 65% of the turbulent luminosity in the inner molecular disk. This suggests that the expansion of the bubbles is a major driver of the turbulent motion of the inner Milky Way molecular gas.

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“…HI self-absorption (e.g. Knapp 1974;Jackson et al 2002;Busfield et al 2006;Roman-Duval et al 2009) relies on absorption of cold HI associated with molecular gas at the near distance from warmer HI at the far distance. In this scenario, the absorption is caused because the cold and warm HI share the same velocity.…”

Section: Distance Recommendation: Resolution Of the Kinematic Distancmentioning

confidence: 99%

Giving physical significance to the Hi-GAL data: determining the distance of cold dusty cores in the Milky Way

Russeil

Pestalozzi

Mottram

et al. 2011

A&A

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Context. Hi-GAL, an open time key-project of the Herschel satellite, was awarded 343 hours observing time to carry out a 5-band photometric imaging survey at 70, 160, 250, 350, and 500 μm of a |b| ≤ 1 • wide strip of the Milky Way Galactic plane in the longitude range −70 • ≤ l ≤ 70 • . Two 2 • × 2 • fields centred at l = 30 • and l = 59 • have been observed with the SPIRE and PACS photometric cameras in parallel mode during the Herschel science demonstration phase (SDP). From the images, compact sources are extracted for which the distance must be established in order to determine their physical properties. Aims. The aim of this paper is to present the distance determination strategy for the Hi-GAL compact sources. We illustrate this strategy for the two fields at l = 30 • and l = 59 • . Methods. The first step to determine the distance is to establish the LSR (local standard of rest) velocity of each compact source. The kinematic distance is then determined assuming a rotation curve for our Galaxy. To resolve the distance ambiguity for sources within the solar circle, we adopt a multiwavelength approach combining extinction maps, optical, and near infrared images, and velocity information from NH 3 , CO and HI data. When sources can be kinematically linked to optical H ii regions, the stellar distance of the exciting stars, when known, can be attributed to all linked sources. Results. In the two 2 • × 2 • SDP fields, 2678 compact sources have been identified and listed in the band-merged catalogue. About 93% of these sources have been assigned a radial velocity and distance. Conclusions. A multiwavelength approach is necessary to assign the correct velocity to sources (especially when CO spectra have a lot of features) and to determine the distance by solving the distance ambiguity. Also, several Hi-GAL sources seem to be in the interarm region. These sources have to be investigated with dedicated programme to be compared with sources located in the spiral arms.

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Resolving the kinematic distance ambiguity of southern massive young stellar object candidates

Cited by 57 publications

References 20 publications

A general catalogue of 6.7 GHz methanol masers

A general catalogue of 6.7 GHz methanol masers

Milky Way Star-Forming Complexes and the Turbulent Motion of the Galaxy's Molecular Gas

Giving physical significance to the Hi-GAL data: determining the distance of cold dusty cores in the Milky Way

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