The Full-fledged Dwarf Irregular Galaxy Leo A

Vansevičius, Vladas; Arimoto, N.; Hasegawa, Takashi; Ikuta, Chisato; Jablonka, P.; Narbutis, D.; Ohta, Kouji; Stonkutė, R.; Tamura, Naoyuki; Vansevičius, V.; Yamada, Yoshiyuki

doi:10.1086/423802

Cited by 66 publications

(96 citation statements)

References 21 publications

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“…Considering two Gaussian functions, we find values of about 5 and 10 km s −1 for the narrow and broad components, respectively. This maybe be the same indication of two-phase interstellar medium as seen in other dwarf galaxies (e.g., Young & Lo 1997;Ryan-Weber et al 2008), including VV124 (Paper I).…”

Section: Neutral Hydrogensupporting

confidence: 78%

“…13, derived using the first moment of the line-of-sight velocity distribution. The kinematics is complex, and there seems to be no clear pattern of rotation or a systematic segregation of blue-shifted and redshifted regions (see also Young & Lo 1997). To test the possible presence of low-level rotation, we extracted a position-velocity (p − v) diagram from the data cube along the major axis of the stellar distribution.…”

Section: Neutral Hydrogenmentioning

confidence: 99%

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The extended structure of the dwarf irregular galaxy Sagittarius

Beccari¹,

Bellazzini²,

Fraternali³

et al. 2014

A&A

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We present a detailed study of the stellar and H  structure of the dwarf irregular galaxy Sagittarius. We use new deep and wide field photometry to trace the surface brightness profile of the galaxy out to 5.0 (corresponding to 1600 pc) and down to µ V 30.0 mag/arcsec 2 , thus showing that the stellar body of the galaxy is much more extended than previously believed, and it is similarly (or more) extended than the overall H  distribution. The whole major-axis profile is consistent with a pure exponential, with a scale radius of 340 pc. The surface density maps reveal that the distribution of old and intermediate-age stars is smooth and remarkably flattened out to its edges, while the associated H  has a much rounder shape, is off-centred and presents multiple density maxima and a significant hole. No clear sign of systemic rotation is detectable in the complex H  velocity field. No metallicity gradient is detected in the old and intermediate age population of the galaxy, and we confirm that this population has a much more extended distribution than young stars (age < ∼ 1 Gyr).

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Section: Neutral Hydrogensupporting

confidence: 78%

Section: Neutral Hydrogenmentioning

confidence: 99%

The extended structure of the dwarf irregular galaxy Sagittarius

Beccari¹,

Bellazzini²,

Fraternali³

et al. 2014

A&A

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“…Rather, there is a secondary, much more extended, lower surface brightness and lower luminosity component to the galaxy that surrounds the highly elliptical main body i.e., a stellar halo. Indeed, such a scenario is not particularly unusual; bright galaxies are known to possess multiple stellar components and more recent work on nearby dwarf galaxies suggests that multiple components are ubiquitous even at low stellar mass (e.g., Martínez-Delgado et al 1999;Lee & Kim 2000;Kleyna et al 2003;Tolstoy et al 2004;Kleyna et al 2004;Vansevičius et al 2004;Battaglia et al 2006Battaglia et al , 2008Battaglia et al , 2011McConnachie et al 2007a;Hidalgo et al 2008;Bellazzini et al 2014). We note that the recent analysis of Sag DIG by Beccari et al (2014) trace the profile to approximately 4 arcmin.…”

Section: On the Content And Structure Of Sag Digmentioning

confidence: 62%

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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“…Seth et al 2007;Seth et al 2008;de Jong et al 2009, for the results on giant spiral galaxies from the GHOST project; Tikhonov 2006a, for the massive irregular M 82; Vansevičius et al 2004, for the very low-mass dIrr Leo A). Recent advanced simulations allow one to make predictions regarding halo chemical abundance trends (Zolotov et al 2010) and their surface brightness profiles following different formation scenarios (e.g.…”

Section: Introductionmentioning

confidence: 99%

HubbleSpace Telescope study of resolved red giant stars in the outer halos of nearby dwarf starburst galaxies

Ryś

Grocholski

Marel

et al. 2011

A&A

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Context. Central starbursts in galaxies are an extreme example of ongoing galaxy evolution. The outer parts of galaxies contain a fossil record of galaxy formation and evolution processes in the more distant past. The characterization of resolved stellar populations allows one a detailed study of these topics. Aims. We observed the outer parts of NGC 1569 and NGC 4449, two of the closest and strongest dwarf starburst galaxies in the local universe, to characterize their stellar density and populations, and obtain new insights into the structure, formation, and evolution of starburst galaxies and galaxy halos. Methods. We obtained HST/WFPC2 images between 5 and 8 scale radii from the center, along the intermediate and minor axes. We performed point-source photometry to determine color magnitude diagrams of I vs. V − I. We compared the results at different radii, including also our prior HST/ACS results for more centrally located fields. Results. We detect stars in the RGB and TP-AGB (carbon star) phases in all outer fields, but not younger stars such as those present at smaller radii. The RGB star density profile is well fit by either a de Vaucouleurs profile or a power-law profile, but has more stars at large radii than a single exponential. To within the uncertainties, there are no radial gradients in the RGB color or carbon-to-RGB-star ratio at large radii. Conclusions. The galaxies have faint outer stellar envelopes that are not tidally truncated within the range of radii addressed by our study. The density profiles suggest that these are not outward extensions of the inner disks, but are instead distinct stellar halos. This agrees with other work on galaxies of similar morphology. The presence of such halos is consistent with predictions of hierarchical galaxy formation scenarios. The halos consist of intermediate-age/old stars, confirming the results of other studies that have shown the starburst phenomenon to be very centrally concentrated. There is no evidence for stellar-population age/metallicity gradients within the halos themselves.

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The Full-fledged Dwarf Irregular Galaxy Leo A

Cited by 66 publications

References 21 publications

The extended structure of the dwarf irregular galaxy Sagittarius

The extended structure of the dwarf irregular galaxy Sagittarius

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

HubbleSpace Telescope study of resolved red giant stars in the outer halos of nearby dwarf starburst galaxies

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