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Mikami, Takamasa; Ogura, K.

doi:10.1023/a:1002872708738

Cited by 12 publications

(9 citation statements)

References 9 publications

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“…(v) l ∼ 110.5, b ∼ 3.0: This area lies within the Cep OB3 association which contains many previously known Hα emitters (see e.g. Mikami & Ogura 2001).…”

Section: The 2d Distribution Of Hα Emittersmentioning

confidence: 80%

“…Drew et al (2005) present multi‐object spectroscopy entered on l ∼ 105.6, b ∼ 4.0 and find 29 definite Hα emitters in the magnitude range 17 ≤ r ′≤ 20.5. l ∼ 110.5, b ∼ 3.0: This area lies within the Cep OB3 association which contains many previously known Hα emitters (see e.g. Mikami & Ogura 2001). l ∼ 135, b ∼ 1.5: This location lies close to several bright rim clouds (BRCs) that are known to harbour Hα emitters.…”

Section: Resultsmentioning

confidence: 96%

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The IPHAS catalogue of Hα emission-line sources in the northern Galactic plane

Witham

Knigge

Drew

et al. 2008

Monthly Notices of the Royal Astronomical Society

111

148

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We present a catalogue of point‐source Hα emission‐line objects selected from the INT/WFC Photometric Hα Survey (IPHAS) of the northern Galactic plane. The catalogue covers the magnitude range 13 ≤r′≤ 19.5 and includes Northern hemisphere sources in the Galactic latitude range −5° < b < 5°. It is derived from ∼1500 deg2 worth of imaging data, which represents 80 per cent of the final IPHAS survey area. The electronic version of the catalogue will be updated once the full survey data become available. In total, the present catalogue contains 4853 point sources that exhibit strong photometric evidence for Hα emission. We have so far analysed spectra for ∼300 of these sources, confirming more than 95 per cent of them as genuine emission‐line stars. A wide range of stellar populations are represented in the catalogue, including early‐type emission‐line stars, active late‐type stars, interacting binaries, young stellar objects and compact nebulae. The spatial distribution of catalogue objects shows overdensities near sites of recent or current star formation, as well as possible evidence for the warp of the Galactic plane. Photometrically, the incidence of Hα emission is bimodally distributed in (r′−i′). The blue peak is made up mostly of early‐type emission‐line stars, whereas the red peak may signal an increasing contribution from other objects, such as young/active low‐mass stars. We have cross‐matched our Hα‐excess catalogue against the emission‐line star catalogue of Kohoutek & Wehmeyer, as well as against sources in SIMBAD. We find that fewer than 10 per cent of our sources can be matched to known objects of any type. Thus IPHAS is uncovering an order of magnitude more faint (r′ > 13) emission‐line objects than were previously known in the Milky Way.

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“…(v) l ∼ 110.5, b ∼ 3.0: This area lies within the Cep OB3 association which contains many previously known Hα emitters (see e.g. Mikami & Ogura 2001).…”

Section: The 2d Distribution Of Hα Emittersmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 96%

The IPHAS catalogue of Hα emission-line sources in the northern Galactic plane

Witham

Knigge

Drew

et al. 2008

Monthly Notices of the Royal Astronomical Society

111

148

View full text Add to dashboard Cite

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“…In addition to the methods discussed above, there are a number of other techniques that can or have been used to identify young stars in OB associations. Historically one of the most common methods has been the use of objective prism surveys or Hα photometry to identify young stars from the excess Hα emission due to accretion or chromospheric activity (e.g., Liu et al 1981;Wiramihardja et al 1989;Mikami & Ogura 2001). The recent Hα Galactic plane surveys IPHAS and VPHAS+ (Drew et al 2005(Drew et al , 2014 have facilitated deep, large-area surveys for young stars with the Hα excess method, with recent applications in Cyg OB2 and Cep OB2 (Vink et al 2008;Barentsen et al 2011).…”

Section: Other Methodsmentioning

confidence: 99%

OB Associations and their origins

Wright

2020

New Astronomy Reviews

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OB associations are unbound groups of young stars made prominent by their bright OB members, and have long been thought to be the expanded remnants of dense star clusters. They have been important in astrophysics for over a century thanks to their luminous massive stars, though their low-mass members have not been well studied until the last couple of decades. This has changed thanks to data from X-ray observations, spectroscopic surveys and astrometry from Gaia that allows their full stellar content to be identified and their dynamics to be studied, which in turn is leading to changes in our understanding of these systems and their origins, with the old picture of Blaauw (1964a) now being superseded. It is clear now that OB associations have considerably more substructure than once envisioned, both spatially, kinematically and temporally. These changes have implications for the star formation process, the formation and evolution of planetary systems, and the build-up of stellar populations across galaxies.

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“…The other four candidates are bluer and with positions in the CMD consistent with being B stars. One of them, [MO2001] 77, is listed as an object with Hα emission by Mikami & Ogura (2001).…”

Section: Villafranca O-013 = Sh 2-158 = Ngc 7538mentioning

confidence: 99%

The Villafranca catalog of Galactic OB groups

Apellániz

Bellido

Barbá

et al. 2020

A&A

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Context. The spectral classifications of the Galactic O-Star Spectroscopic Survey (GOSSS) and the astrometric and photometric data from Gaia have significantly improved our ability to measure distances and determine memberships of stellar groups (clusters, associations, or parts thereof) with OB stars. In the near future, the situation will be further improved thanks to subsequent Gaia data releases and new photometric and spectroscopic surveys. Aims. We initiated a program to identify and determine the membership of Galactic stellar groups with OB stars and measure distances to them. Given the data currently available, we started with the identification and distance determinations of groups with O stars. In this paper, we concentrate on groups that contain stars with the earliest spectral subtypes. Methods. We used GOSSS to select Galactic stellar groups with O2–O3.5 stars and the method described in paper 0 of this series, which combines Gaia DR2 G + GBP + GRP photometry, positions, proper motions, and parallaxes to assign robust memberships and measure distances. We also included Collinder 419 and NGC 2264, the clusters cited in that paper, to generate our first list of 16 O-type Galactic stellar groups. Results. We derived distances, determined the membership, and analyzed the structure of sixteen Galactic stellar groups with O stars, Villafranca O-001 to Villafranca O-016, including the fourteen groups with the earliest-O-type optically accessible stars known in the Milky Way. We compared our distance with previous results from the literature and establish that the best consistency is with (the small number of) VLBI parallaxes and the worst is with kinematic distances. Our results indicate that very massive stars can form in relatively low-mass clusters or even in near-isolation, as is the case for the Bajamar star in the North America nebula. This lends support to the hierarchical scenario of star formation, where some stars are born in well-defined bound clusters but others are born in associations that are unbound from the beginning: groups of newborn stars come in many shapes and sizes. We propose that HD 64 568 and HD 64 315 AB could have been ejected simultaneously from Haffner 18 (Villafranca O-012 S). Our results are consistent with a difference of ≈20 μas in the Gaia DR2 parallax zero point between bright and faint stars.

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Cited by 12 publications

References 9 publications

The IPHAS catalogue of Hα emission-line sources in the northern Galactic plane

The IPHAS catalogue of Hα emission-line sources in the northern Galactic plane

OB Associations and their origins

The Villafranca catalog of Galactic OB groups

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