A Survey of Local Group Galaxies Currently Forming Stars. I.<i>UBVRI</i>Photometry of Stars in M31 and M33

Massey, Philip; Olsen, Knut; Hodge, P. W.; Strong, Shay B.; Jacoby, George H.; Schlingman, W. M.; Smith, R. C.

doi:10.1086/503256

Cited by 403 publications

(756 citation statements)

References 45 publications

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“…3, the early type WN source MC8 is by far the brightest source within the MA 1 nebula. Indeed, ground-based photometry from Massey et al (2006) indicates V = 16.14 mag, from which E(B−V) = 0.06 mag (via C Hβ = 0.09) implies M V = −8.7 mag for our assumed distance of 840 kpc. In contrast, absolute magnitudes of WN-type stars in the Large Magellanic Cloud range from -2 to -7.5 mag (Crockett et al 2007), with M V = −4 mag typical for single early-type WN stars.…”

Section: Stellar Atmosphere Models For the Wn Source Mc8mentioning

confidence: 89%

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Gemini GMOS spectroscopy of HeII nebulae in M 33

Kehrig

Oey

Crowther

et al. 2011

A&A

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We have carried out a narrow-band survey of the Local Group galaxy, M 33, in the HeII λ4686 emission line, to identify HeII nebulae in this galaxy. With spectroscopic follow-up observations, we confirm three of seven candidate objects, including identification of two new HeII nebulae, BCLMP651, HBW673. We also obtain spectra of associated ionizing stars for all the HII regions, identifying two new WN stars. We demonstrate that the ionizing source for the known HeII nebula, MA 1, is consistent with being the earlytype WN star MC8 (M 33-WR14), by carrying out a combined stellar and nebular analysis of MC8 and MA 1. We were unable to identify the helium ionizing sources for HBW 673 and BCLMP 651, which do not appear to be Wolf-Rayet stars. According to the [OIII]λ5007/Hβ vs.[NII]λ6584/Hα diagnostic diagram, excitation mechanisms apart from hot stellar continuum are needed to account for the nebular emission in HBW 673, which appears to have no stellar source at all.

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Section: Stellar Atmosphere Models For the Wn Source Mc8mentioning

confidence: 89%

“…Notes. (a) LGGS designation (JHHMMSS.ss+DDMMSS.s) from Massey et al (2006). ( Reddening-corrected emission-line intensities, normalized to Hβ, are shown in Table 4, together with the values of C(Hβ) and EW abs that provide the best match between the corrected and the theoretical Balmer line ratios.…”

Section: Spectrophotometric Datamentioning

confidence: 99%

Gemini GMOS spectroscopy of HeII nebulae in M 33

Kehrig

Oey

Crowther

et al. 2011

A&A

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“…Here we implement an extension of the ZCR09 method, based on a fully Bayesian approach, similar to that adopted and validated by a number of works in the literature of the last decade (e.g., Kauffmann et al 2003;Salim et al 2005;Gallazzi et al 2005;da Cunha et al 2008;Gallazzi & Bell 2009). Our imaging dataset is composed of mosaic maps in the B, V, and I bands from the Local Group Survey (Massey et al 2006) and g and i bands from the Sloan Digital Sky Survey (SDSS, York et al 2000). After processing the images as described in the following subsections, we perform a pixel by pixel stellar population analysis by comparing the measured magnitudes in the five bands with the corresponding magnitudes derived from a comprehensive model library of 150 000 synthetic spectral energy distributions (SED).…”

Section: Method: From Light To Stellar Massmentioning

confidence: 99%

Dynamical signatures of a ΛCDM-halo and the distribution of the baryons in M 33

Corbelli

Thilker

Zibetti

et al. 2014

A&A

153

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Aims. We determine the mass distribution of stars, gas, and dark matter in M 33 to test cosmological models of galaxy formation and evolution. Methods. We map the neutral atomic gas content of M 33 using high resolution Very Large Array and Green Bank Telescope observations of the 21 cm HI line emission. A tilted ring model is fitted to the HI datacube to determine the varying spatial orientation of the extended gaseous disk and the rotation curve. We derive the stellar mass surface density map of M 33's optical disk via pixel-SED fitting methods based on population synthesis models that allow for positional changes in star formation history. Stellar and gas maps are used in the dynamical analysis of the rotation curve to constrain the dark halo properties. Results. The disk of M 33 warps from 8 kpc outward without substantial change of its inclination with respect to the line of sight; the line of nodes rotates clockwise toward the direction of M 31. Rotational velocities rise steeply with radius in the inner disk, reaching 100 km s −1 in 4 kpc, then the rotation curve becomes more perturbed and flatter with velocities as high as 120-130 km s −1 out to 2.7 R 25 . The stellar surface density map highlights a star-forming disk with a varying mass-to-light ratio. At larger radii, a dynamically relevant fraction of the baryons are in gaseous form. A dark matter halo with a Navarro-Frenk-White density profile, as predicted by hierarchical clustering and structure formation in a ΛCDM cosmology, provides the best fits to the rotation curve. Dark matter is relevant at all radii in shaping the rotation curve and the most likely dark halo has a concentration C 9.5 and a total mass of 4.3(±1.0) × 10 11 M . This imples a baryonic fraction of order 0.02 and the evolutionary history of this galaxy should therefore account for loss of a large fraction of its original baryonic content.

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“…However, a systematic, modern survey including more distant dwarfs is lacking. Arguably the most systematic study of a subset of these galaxies is Massey et al (2006), who surveyed ten star forming galaxies to determine certain properties relating to star formation activity. In addition, the Local Cosmology from Isolated Dwarfs (LCID) survey studied six nearby isolated dwarf galaxies in the Local Group using deep HST imaging (see Gallart et al 2015 and references within).…”

Section: The Solo Dwarfsmentioning

confidence: 99%

Solo dwarfs I: survey introduction and first results for the Sagittarius dwarf irregular galaxy

Higgs¹,

McConnachie²,

Irwin³

et al. 2016

Mon. Not. R. Astron. Soc.

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We introduce the Solitary Local Dwarfs Survey (Solo), a wide field photometric study targeting every isolated dwarf galaxy within 3 Mpc of the Milky Way. Solo is based on (u)gi multi-band imaging from CFHT/MegaCam for northern targets, and Magellan/Megacam for southern targets. All galaxies fainter than M V −18 situated beyond the nominal virial radius of the Milky Way and M31 ( 300 kpc) are included in this volume-limited sample, for a total of 42 targets. In addition to reviewing the survey goals and strategy, we present results for the Sagittarius Dwarf Irregular Galaxy (Sag DIG), one of the most isolated, low mass galaxies, located at the edge of the Local Group. We analyze its resolved stellar populations and their spatial distributions. We provide updated estimates of its central surface brightness and integrated luminosity, and trace its surface brightness profile to a level fainter than 30 mag./sq.arcsec. Sag DIG is well described by a highly elliptical (disk-like) system following a single component Sersic model. However, a low-level distortion is present at the outer edges of the galaxy that, were Sag DIG not so isolated, would likely be attributed to some kind of previous tidal interaction. Further, we find evidence of an extremely low level, extended distribution of stars beyond ∼ 5 arcmins (> 1.5 kpc) that suggests Sag DIG may be embedded in a very low density stellar halo. We compare the stellar and HI structures of Sag DIG, and discuss results for this galaxy in relation to other isolated, dwarf irregular galaxies in the Local Group.

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A Survey of Local Group Galaxies Currently Forming Stars. I.UBVRIPhotometry of Stars in M31 and M33

Cited by 403 publications

References 45 publications

Gemini GMOS spectroscopy of HeII nebulae in M 33

Gemini GMOS spectroscopy of HeII nebulae in M 33

Dynamical signatures of a ΛCDM-halo and the distribution of the baryons in M 33

Solo dwarfs I: survey introduction and first results for the Sagittarius dwarf irregular galaxy

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