Long‐slit échelle spectroscopy of galactic outflows: The case ofNGC 4449

Bomans, D. J.; Weis, Karsten

doi:10.1002/asna.201312019

Cited by 6 publications

(5 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, the similarity in oxygen abundance between H II regions and PNe suggests that this is not the case. The galactic outflow observed in NGC 4449 (Della Ceca et al 1997;Summers et al 2003;Bomans & Weis 2014) may have played an important role, expelling the recently produced α-elements. Accretion of metal poor gas or acquisition of smaller gaseous systems may have also contributed to dilute the metals in the ISM.…”

Section: Distributionsmentioning

confidence: 99%

Planetary Nebulae and H ii Regions in the Starburst Irregular Galaxy NGC 4449 from LBT MODS Data

Annibali

Tosi

Romano

et al. 2017

ApJ

View full text Add to dashboard Cite

We present deep 3500−10000Å spectra of H II regions and planetary nebulae (PNe) in the starburst irregular galaxy NGC 4449, acquired with the Multi Object Double Spectrograph at the Large Binocular Telescope. Using the "direct" method, we derived the abundance of He, N, O, Ne, Ar, and S in six H II regions and in four PNe in NGC 4449. This is the first case of PNe studied in a starburst irregular outside the Local Group. Our H II region and PN sample extends over a galactocentric distance range of ≈2 kpc and spans ≈0.2 dex in oxygen abundance, with average values of 12 + log(O/H) = 8.37 ± 0.05 and 8.3 ± 0.1 for H II regions and PNe, respectively. PNe and H II regions exhibit similar oxygen abundances in the galacto-centric distance range of overlap, while PNe appear more than ∼1 dex enhanced in nitrogen with respect to H II regions. The latter result is the natural consequence of N being mostly synthesized in intermediate-mass stars and brought to the stellar surface during dredge-up episodes. On the other hand, the similarity in O abundance between H II regions and PNe suggests that NGC 4449' s interstellar medium has been poorly enriched in α-elements since the progenitors of the PNe were formed. Finally, our data reveal the presence of a negative oxygen gradient for both H II regions and PNe, whilst nitrogen does not exhibit any significant radial trend. We ascribe the (unexpected) nitrogen behaviour as due to local N enrichment by the conspicuous Wolf-Rayet population in NGC 4449.

show abstract

Section: Distributionsmentioning

confidence: 99%

Planetary Nebulae and H ii Regions in the Starburst Irregular Galaxy NGC 4449 from LBT MODS Data

Annibali

Tosi

Romano

et al. 2017

ApJ

View full text Add to dashboard Cite

show abstract

“…High-resolution imaging of this galaxy by the Hubble Space Telescope (HST) (Figure 2) reveals populations of young and old stellar clusters which are indicative of an active star-formation history (Annibali et al 2011). 0.017±0.001 a Taken from NED b Foreground Galactic extinction (Schlafly & Finkbeiner 2011) Long-slitéchelle spectroscopy has revealed interesting kinematic features in NGC 4449 -expanding bubbles, supergiant shells and high velocity filaments, along with diffuse ionised gas (Bomans & Weis 2014;Hunter & Gallagher 1997). The heavy-element (O i, Si ii, Fe ii) absorption lines of NGC 4449 suggest the occurrence of turbulent broadening within the neutral gas (James et al 2014).…”

Section: Introductionmentioning

confidence: 99%

A GMOS-N IFU study of the central H ii region in the blue compact dwarf galaxy NGC 4449: kinematics, nebular metallicity and star formation★

Kumari

James

Irwin

2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We use integral field spectroscopic (IFS) observations from the Gemini North Multi-Object Spectrograph (GMOS-N) to study the central H ii region in a nearby blue compact dwarf (BCD) galaxy NGC 4449. The IFS data enable us to explore the variation of physical and chemical conditions of the star-forming region and the surrounding gas on spatial scales as small as 5.5 pc. Our kinematical analysis shows possible signatures of shock ionisation and shell structures in the surroundings of the star-forming region. The metallicity maps of the region, created using direct T e and indirect strong line methods (R 23 , O3N2 and N2), do not show any chemical variation. From the integrated spectrum of the central H ii region, we find a metallicity of 12 + log(O/H) = 7.88 ± 0.14 (∼ 0.15 +0.06 −0.04 Z ) using the direct method. Comparing the central H ii region metallicity derived here with those of H ii regions throughout this galaxy from previous studies, we find evidence of increasing metallicity with distance from the central nucleus. Such chemical inhomogeneities can be due to several mechanisms, including gas-loss via supernova blowout, galactic winds, or metal-poor gas accretion. However, we find that the localised area of decreased metallicity aligns spatially with the peak of star-forming activity in the galaxy, suggesting that gasaccretion may be at play here. Spatially-resolved IFS data for the entire galaxy is required to confirm the metallicity inhomogeneity found in this study, and determine its possible cause.

show abstract

“…First such analyses are already appearing for galaxies in the Scultor group: NGC 300 [184] and NGC 7793 [185]. An unfortunate weakness in the currently available instrumentation are high-dispersion spectrographs fed by long-slits and IFUs, an important capability for kinematics/energetics of nebulae, which is becoming rare [186] at the intermediate and large telescopes. High-multiplex spectroscopic survey instruments at large telescopes, like e.g., Hectospec at the MMT, and soon MOONS and 4MOST at ESO telescopes, as well as WEAVE at the WHT, can be very useful tools to set LBVs in context to their massive star environment, as they are capable of providing good quality spectra for many photometrically selected LBV candidates (as well as other supergiants).…”

Section: Discussionmentioning

confidence: 99%

Luminous Blue Variables

Weis

Bomans

2020

Galaxies

View full text Add to dashboard Cite

Luminous Blue Variables are massive evolved stars, here we introduce this outstanding class of objects. Described are the specific characteristics, the evolutionary state and what they are connected to other phases and types of massive stars. Our current knowledge of LBVs is limited by the fact that in comparison to other stellar classes and phases only a few “true” LBVs are known. This results from the lack of a unique, fast and always reliable identification scheme for LBVs. It literally takes time to get a true classification of a LBV. In addition the short duration of the LBV phase makes it even harder to catch and identify a star as LBV. We summarize here what is known so far, give an overview of the LBV population and the list of LBV host galaxies. LBV are clearly an important and still not fully understood phase in the live of (very) massive stars, especially due to the large and time variable mass loss during the LBV phase. We like to emphasize again the problem how to clearly identify LBV and that there are more than just one type of LBVs: The giant eruption LBVs or η Car analogs and the S Dor cycle LBVs.

show abstract

Long‐slit échelle spectroscopy of galactic outflows: The case ofNGC 4449

Cited by 6 publications

References 38 publications

Planetary Nebulae and H ii Regions in the Starburst Irregular Galaxy NGC 4449 from LBT MODS Data

Planetary Nebulae and H ii Regions in the Starburst Irregular Galaxy NGC 4449 from LBT MODS Data

A GMOS-N IFU study of the central H ii region in the blue compact dwarf galaxy NGC 4449: kinematics, nebular metallicity and star formation★

Luminous Blue Variables

Contact Info

Product

Resources

About