Herbig Ae/Be Stars in the Magellanic Bridge

Nishiyama, Shogo; Haba, Y.; Kato, Daisuke; Baba, Daisuke; Hatano, Hitoshi; Tamura, Motohide; Ishihara, Akika; Nagata, T.; Sugitani, Koji; Matsunaga, Noriyuki; Fukushi, H.; Kusakabe, Nobuhiko; Sato, Shuji

doi:10.1086/511326

Cited by 18 publications

(33 citation statements)

References 36 publications

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“…Finally, there are others types of young objects, such as Herbig–Haro stars (e.g. Subramaniam et al 2006; Nishiyama et al 2007), but we do not attempt to identify these specifically in this work.…”

Section: Analysesmentioning

confidence: 99%

Spectrophotometric distances to Galactic H ii regions

Moisés¹,

Damineli²,

Figuerêdo³

et al. 2010

Monthly Notices of the Royal Astronomical Society

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We present a near‐infrared study of the stellar content of 35 H ii regions in the Galactic plane, 24 of which have been classified as giant H ii regions. We have selected these optically obscured star‐forming regions from the catalogues of Russeil, Conti & Crowther and Bica et al. In this paper, we have used the near‐infrared domain J‐, H‐ and Ks‐band colour images to visually inspect the sample. Also, we have used colour‐colour and colour–magnitude diagrams to indicate ionizing star candidates, as well as the presence of young stellar objects such as classical T Tauri stars and massive young stellar objects (MYSOs). We have obtained Spitzer Infrared Array Camera images for each region to help further characterize them. Spitzer and near‐infrared morphology were used to place each cluster in an evolutionary phase of development. Spitzer photometry was also used to classify the MYSOs. A comparison of the main sequence in the colour–magnitude diagrams for each observed cluster was used to infer whether or not the cluster kinematic distance is consistent with brightnesses of the stellar sources. We find qualitative agreement for a dozen of the regions, but about half the regions have near‐infrared photometry that suggests they may be closer than the kinematic distance. A significant fraction of these already have spectrophotometric parallaxes that support smaller distances. These discrepancies between kinematic and spectrophotometric distances are not a result of the spectrophotometric methodologies, as independent non‐kinematic measurements are in agreement with the spectrophotometric results. For instance, the trigonometric parallaxes of star‐forming regions were collected from the literature and show the same effect of smaller distances when compared to the kinematic results. In our sample of H ii regions, most of the clusters are evident in the near‐infrared images. Finally, it is possible to distinguish among qualitative evolutionary stages for these objects.

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Section: Analysesmentioning

confidence: 99%

Spectrophotometric distances to Galactic H ii regions

Moisés¹,

Damineli²,

Figuerêdo³

et al. 2010

Monthly Notices of the Royal Astronomical Society

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“…Muller et al (2004) reported that the MB is composed of two kinematically and morphologically distinct structures and shows a remarkable velocity offset around δ = −73.5 • in the δ-V rad plane. The discovery of molecular clouds (Mizuno et al 2006) and the possible detection of pre-mainsequence stars (Nishiyama et al 2007) in the MB strongly suggest that star formation in the MB is currently ongoing and possibly triggered by the last LMC-SMC interaction. Harris (2007) did not detect an older stellar population in the MB and thus suggested that the MB originates purely from gaseous components of the MCs.…”

Section: On the Possible Absence Of Older Stars In The Mbmentioning

confidence: 99%

Origin of Structural and Kinematic Properties of the Small Magellanic Cloud

Bekki

Chiba

2009

Publ. – Astron. Soc. Aust

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Abstract:We investigate structural, kinematic and chemical properties of stars and gas in the Small Magellanic Cloud (SMC) interacting with the Large Magellanic Cloud (LMC) and the Galaxy based on a series of selfconsistent chemodynamical simulations. We adopt a new 'dwarf spheroidal model' in which the SMC initially has both old stars with a spherical spatial distribution and an extended Hi gas disk. We mainly investigate the evolution of the SMC for the last ∼3 Gyr, during which the Magellanic Stream (MS) and the Magellanic Bridge (MB) could have formed as a result of the LMC-SMC-Galaxy interaction. Our principal results, which can be tested against observations, are as follows: The final spatial distribution of the old stars projected onto the sky is spherical, even after strong LMC-SMC-Galaxy interaction, whereas that of the new ones is significantly flattened and appears to form a bar structure. Old stars have a line-of-sight velocity dispersion σ 30 km s −1 and slow rotation, with a maximum rotational velocity, V < 20 km s −1 and show asymmetry in the radial profiles. New stars have a smaller σ than old ones and a significant amount of rotation (V/σ > 1). Hi gas shows velocity dispersions of σ = 10-40 km s −1 , a high maximum rotational velocity (V ∼ 50 km s −1 ) and a spatial distribution similar to that of new stars. New stars with ages younger than 3 Gyr show a negative metallicity gradient in the sense that more metal-rich stars are located in the inner regions of the SMC. The MB inevitably contains old stars with surface mass densities of 6-300 × 10 4 M deg −2 depending on initial stellar distributions of the modeled SMC. We find that the dwarf spheroidal model can explain more selfconsistently the observed kinematic properties of stars and gas, compared with another type of the model ('the disk model') in which the SMC initially consists of stellar and gas disks. We suggest that, to better understand its evolution, the SMC needs to be modeled as having a spheroidal component, rather than being a pure disk.

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“…What is the fate of the MCs and will they merge with the MW? Will the Bridge evolve into a dwarf galaxy (Nishiyama et al 2007)? Does the LMC have an ordinary bar and how does it influence the LMC evolution?…”

Section: Introductionmentioning

confidence: 99%

The VMC survey

Cioni

Clementini

Girardi

et al. 2011

A&A

322

304

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Context. The new VISual and Infrared Telescope for Astronomy (VISTA) has started operations. Over its first five years it will be collecting data for six public surveys, one of which is the near-infrared Y JK s VISTA survey of the Magellanic Clouds system (VMC). This survey comprises the Large Magellanic Cloud (LMC), the Small Magellanic Cloud, the Magellanic Bridge connecting the two galaxies and two fields in the Magellanic Stream. Aims. This paper provides an overview of the VMC survey strategy and presents first science results. The main goals of the VMC survey are the determination of the spatially-resolved star-formation history and the three-dimensional structure of the Magellanic system. The VMC survey is therefore designed to reach stars as faint as the oldest main sequence turn-off point and to constrain the mean magnitude of pulsating variables such as RR Lyrae stars and Cepheids. This paper focuses on observations of VMC fields in the LMC obtained between November 2009 and March 2010. These observations correspond to a completeness of 7% of the planned LMC fields. Methods. The VMC data are comprised of multi-epoch observations which are executed following specific time constraints. The data were reduced using the VISTA Data Flow System pipeline with source catalogues, including astrometric and photometric corrections, produced and made available via the VISTA Science Archive. The VMC data will be released to the astronomical community following the European Southern Observatory's Public Survey policy. The analysis of the data shows that the sensitivity in each wave band agrees with expectations. Uncertainties and completeness of the data are also derived. Results. The first science results, aimed at assessing the scientific quality of the VMC data, include an overview of the distribution of stars in colour-magnitude and colour-colour diagrams, the detection of planetary nebulae and stellar clusters, and the K s band light-curves of variable stars. Conclusions. The VMC survey represents a tremendous improvement, in spatial resolution and sensitivity, on previous panoramic observations of the Magellanic system in the near-infrared, providing a powerful complement to deep observations at other wavelengths.

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Herbig Ae/Be Stars in the Magellanic Bridge

Cited by 18 publications

References 36 publications

Spectrophotometric distances to Galactic H ii regions

Spectrophotometric distances to Galactic H ii regions

Origin of Structural and Kinematic Properties of the Small Magellanic Cloud

The VMC survey

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