<i>Erratum</i>The chemical abundances in a sample of dwarf irregular galaxies

Gamez, Ana María Hidalgo; Masegosa, J.; Olofsson, Katarina

doi:10.1051/0004-6361:20010864

Cited by 2 publications

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“…It appears to be detached from the main body. Furthermore, Hidalgo‐Gámez, Masegosa & Olofsson (2001) pointed out that it differs significantly from the main body in oxygen abundance. Therefore, the question arises whether it is an own system interacting with IC 4662 (e.g.…”

Section: Discussionmentioning

confidence: 99%

A kinematic study of the neutral and ionized gas in the irregular dwarf galaxies IC 4662 and NGC 5408★

Eymeren

Koribalski

López-Sánchez

et al. 2010

Monthly Notices of the Royal Astronomical Society

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The feedback between massive stars and the interstellar medium is one of the most important processes in the evolution of dwarf galaxies. This interaction results in numerous neutral and ionized gas structures that have been found both in the disc and in the halo of these galaxies. However, their origin and fate are still poorly understood. We here present new H i and optical data of two Magellanic irregular dwarf galaxies in the Local Volume: IC 4662 and NGC 5408. The H i line data were obtained with the Australia Telescope Compact Array and are part of the ‘Local Volume H i Survey’. They are complemented by optical images and spectroscopic data obtained with the European Southern Observatory (ESO) New Technology Telescope and the ESO 3.6‐m telescope. Our main aim is to study the kinematics of the neutral and ionized gas components in order to search for outflowing gas structures and to make predictions about their fate. Therefore, we perform a Gaussian decomposition of the H i and Hα line profiles. We find the H i gas envelopes of IC 4662 and NGC 5408 to extend well beyond the optical discs, with H i to optical diameter ratios of above 4. The optical disc is embedded into the central H i maximum in both galaxies. However, higher resolution H i maps show that the H i intensity peaks are typically offset from the prominent H ii regions. While NGC 5408 shows a fairly regular H i velocity field, which allows us to derive a rotation curve, IC 4662 reveals a rather twisted H i velocity field, possibly caused by a recent merger event. We detect outflows with velocities between 20 and 60 km s−1 in our Hα spectra of both galaxies, sometimes with H i counterparts of similar velocity. We suggest the existence of expanding superbubbles, especially in NGC 5408. This is also supported by the detection of full width at half‐maxima as high as 70 km s−1 in Hα, which cannot be explained by thermal broadening alone. In the case of NGC 5408, we compare our results with the escape velocity of the galaxy, which shows that the measured expansion velocities are in all cases too low to allow the gas to escape from the gravitational potential of NGC 5408. This result is consistent with studies of other dwarf galaxies.

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Section: Discussionmentioning

confidence: 99%

A kinematic study of the neutral and ionized gas in the irregular dwarf galaxies IC 4662 and NGC 5408★

Eymeren

Koribalski

López-Sánchez

et al. 2010

Monthly Notices of the Royal Astronomical Society

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show abstract

“…It appears to be detached from the main body. Furthermore, Hidalgo-Gámez et al (2001) pointed out that it differs significantly from the main body in oxygen abundance. Therefore, the question arises whether it is an own system interacting with IC 4662 (e.g., H. Lee, private communication) or just an unusually placed OB association.…”

Section: The Southern H II Region In Ic 4662mentioning

confidence: 99%

A kinematic study of the neutral and ionised gas in the irregular dwarf galaxies IC 4662 and NGC 5408

van Eymeren,

Koribalski,

Lopez-Sanchez

et al. 2010

Preprint

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The feedback between massive stars and the interstellar medium is one of the most important processes in the evolution of dwarf galaxies. This interaction results in numerous neutral and ionised gas structures that have been found both in the disc and in the halo of these galaxies. However, their origin and fate are still poorly understood. We here present new H i and optical data of two Magellanic irregular dwarf galaxies in the Local Volume: IC 4662 and NGC 5408. The H i line data were obtained with the Australia Telescope Compact Array and are part of the "Local Volume H i Survey". They are complemented by optical images and spectroscopic data obtained with the ESO New Technology Telescope and the ESO 3.6m telescope. Our main aim is to study the kinematics of the neutral and ionised gas components in order to search for outflowing gas structures and to make predictions about their fate. Therefore, we perform a Gaussian decomposition of the H i and Hα line profiles. We find the H i gas envelopes of IC 4662 and NGC 5408 to extend well beyond the optical discs, with H i to optical diameter ratios above four. The optical disc is embedded into the central H i maximum in both galaxies. However, higher resolution H i maps show that the H i intensity peaks are typically offset from the prominent H ii regions. While NGC 5408 shows a fairly regular H i velocity field, which allows us to derive a rotation curve, IC 4662 reveals a rather twisted H i velocity field, possibly caused by a recent merger event. We detect outflows with velocities between 20 and 60 km s −1 in our Hα spectra of both galaxies, sometimes with H i counterparts of similar velocity. We suggest the existence of expanding superbubbles, especially in NGC 5408. This is also supported by the detection of FWHMs as high as 70 km s −1 in Hα, which cannot be explained by thermal broadening alone. In case of NGC 5408, we compare our results with the escape velocity of the galaxy, which shows that the measured expansion velocities are in all cases too low to allow the gas to escape from the gravitational potential of NGC 5408. This result is consistent with studies of other dwarf galaxies.

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ErratumThe chemical abundances in a sample of dwarf irregular galaxies

Abstract: Due to a mistake, Figs. 1a, 1b, 1c and 2b are incorrect. Those spectra have been replaced and appear in the electronic version of the article.Send offprint requests to: K. Olofsson,

Cited by 2 publications

References 0 publications

A kinematic study of the neutral and ionized gas in the irregular dwarf galaxies IC 4662 and NGC 5408★

A kinematic study of the neutral and ionized gas in the irregular dwarf galaxies IC 4662 and NGC 5408★

A kinematic study of the neutral and ionised gas in the irregular dwarf galaxies IC 4662 and NGC 5408

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