The Central Regions of M82 – Scattered Light and Extinction

Notni, P.; Bronkalla, W.

doi:10.1002/asna.2113050402

Cited by 11 publications

(6 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Foreground extinction from our galaxy is very low, Ag x 0.15 mag (Burstein and Heiles 1984) or Av x 0.1 f .15 mag (Freedman et al 1994). In M82 itself, the outer parts are only moderately dusty save for a dense extinction belt along the southern boundary which is the probable locus of the main plane of M82 (Notni and Bronkalla 1984). The outer part of this extinction belt passes through the south-eastern (right) part of our field; in the other regions the extinction is expected to be low, but not zero.…”

Section: Extinction In M82mentioning

confidence: 95%

“…The outer parts are relatively extinction-free, however (Notni and Bronkalla 1984). It is these regions, therefore, where we can look for young stars in the disk.…”

Section: Brouillet Et Al 1991)mentioning

confidence: 98%

“…Isophote B-V = +0.8 mag in the upper part of the field from surface photometry. Photographic measurements (Notni and Bronkalla 1984), adaptively smoothed to 47 x 47". Left of the nearly vertical contour the colour is bluer, to the right it is redder (with some blue islands).…”

Section: Extinction In M82mentioning

confidence: 99%

See 2 more Smart Citations

Young stars in the disk of M82

1996

Self Cite

View full text Add to dashboard Cite

We present CCD V l c photometry in a field 1.9 x 1 . 3 square arcmin and positioned about 3 arcmin north-east of the centre of M82. More than 100 stars have been identified and measured above the photometric limits V = 23m5, I = 22m. Most of the objects fainter than V Starlike as well as 2-3 somewhat diffuse objects -candidates of globular clusters -preferentially occupy yellow colours in the colour-magnitude diagram; extreme blue and red objects are missing. The colour-magnitude diagram indicates continuing star formation in this part of the disk. The absence of blue stars is caused by reddening; no convincing explanation is found for the missing red supergiants. Young stars are distributed throughout the whole field, the youngest being concentrated in associations at the SW edge of the field. To cope with the very irregular background created by the galaxy's main body and with the low contrast of many of the stars against this background, a modified photometric method is introduced in which the background is estimated using the intensities in a ring drawn very tightly around the star in the wings of the point spread function.Key words: interacting galaxies -young stars -M82 A A A subject classification: 158 20" should be members of M82 as expected from the statistics of foreground stars. IntroductionThe galaxy M82, a member of the M81 group of galaxies, has been a favourite object to observers ever since Lynds and Sandage (1963) found evidence of energetic events in its central region, now known to be the seat of a huge starburst. Despite the vigorous starforming activity at its centre, the outer parts of M82 seem to show no sign of recent star formation; no HI1 regions, no bright young objects, and no spiral arms are seen. This led Sandage and Brucato (1979) to include it as a member of the small morphological group of "Amorphous Galaxies" showing no structure in their main body. The whole central M81 group is embedded in a huge cloud of intergalactic HI. It is now generally agreed that this cloud is the result of a passage of one or two galaxies (M82, NGC3077) near M81, leading to tidal disturbances especially in the interstellar medium of these galaxies. Tidal tails of HI are now seen joining the three galaxies (Appleton et al. 1981, Yun et al. 1994. The time passed since these events has been estimated by numerical modelling of the interaction; for M82 values between. 2...5 . lo8 yr have been found (for instance Kilian 1980, Brouillet et al. 1991).It has been suggested already by O'Connell and Mangano (1978) that the absence of young stars in the outer parts of M82 may be the result of this interaction, which severely disturbed the interstellar medium in M82, making further star formation impossible. Scattered star formation occured, however, in some limited regions in the disk, probably triggered by interaction with backfalling intergalactic material. If this scenario applies, the age 16 Astron. Nachr. 317 (1996) 4 226 Astron. Nachr. 317 (1996) 4 and the distribution of the youngest stars in the outskir...

show abstract

Section: Extinction In M82mentioning

confidence: 95%

“…The outer parts are relatively extinction-free, however (Notni and Bronkalla 1984). It is these regions, therefore, where we can look for young stars in the disk.…”

Section: Brouillet Et Al 1991)mentioning

confidence: 98%

See 1 more Smart Citation

Young stars in the disk of M82

1996

Self Cite

View full text Add to dashboard Cite

show abstract

“…Along each sight-line through the galaxy there is a combination of emission due to reflection off dust, as indicated by polarisation measurements (e.g. Notni & Bronkalla 1984;Scarrott et al 1991;Jones 2000), as well as sources that are seen directly. Bland & Tully (1988) discovered a weak, uniform, broad (300 km s −1 ) emission component in the M82 halo which they associated with scattered light from the nuclear region.…”

Section: The Broad Component (C2)mentioning

confidence: 99%

The Optical Structure of the Starburst Galaxy M82. I. Dynamics of the Disk and Inner-Wind

Westmoquette

Smith

Gallagher

et al. 2009

ApJ

View full text Add to dashboard Cite

We present Gemini-North GMOS-IFU observations of the central starburst clumps and inner wind of M82, together with WIYN DensePak IFU observations of the inner 2 × 0.9 kpc of the disk. These cover the emission lines of Hα, [N ii], [S ii], and [S iii] at a spectral resolution of 45-80 km s −1 . The high signal-to-noise of the data is sufficient to accurately decompose the emission line profiles into multiple narrow components (FWHM ∼ 30-130 km s −1 ) superimposed on a broad (FWHM ∼ 150-350 km s −1 ) feature. This paper is the first of a series examining the optical structure of M82's disk and inner wind; here we focus on the ionized gaseous and stellar dynamics and present maps of the relevant emission line properties.Our observations show that ionized gas in the starburst core of M82 is dynamically complex with many overlapping expanding structures located at different radii. Localised line splitting of up to 100 km s −1 in the narrow component is associated with expanding shells of compressed, cool, photoionized gas at the roots of the superwind outflow. We have been able to associate some of this inner-wind gas with a distinct outflow channel characterised by its dynamics and gas density patterns, and we discuss the consequences of this discovery in terms of the developing wind outflow.The broad optical emission line component is observed to become increasingly important moving outward along the outflow channel, and in general with increasing height above/below the plane. Following our recent work on the origins of this component, we associate it with turbulent gas in wind-clump interface layers and hence sites of mass loading, meaning that the turbulent mixing of cooler gas into the outflowing hot gas must become increasingly important with height, and provides powerful direct evidence for the existence of mass-loading over a large, spatially extended area reaching far into the inner wind. We discuss the consequences and implications of this.We confirm that the rotation axis of the ionized emission-line gas is offset from the stellar rotation axis and the photometric major axis by ∼12 • , not only within the nuclear regions but over the whole inner 2 kpc of the disk. This attests to the perturbations introduced from M82's past interactions within the M81 group. Finally, finding a turn-over in the stellar and ionized gas rotation curves on both sides of the galaxy indicates that our sight line, in places, extends at least half way through disk, and conflicts with the high levels of obscuration usually associated with the nuclear regions of M82.

show abstract

“…In contrast, Notni and Bronkalla (1984) derived the population distribution in the inner regions of M82 assumimg two distinct populations (each with small τ ) in each pixel in their analysis of photographic data. Similarly, the integrated colour for a sample of dwarf galaxies was interpreted by Almoznino and Brosch (1998) as a combination of a young (3-13Myr) and an old (1-2 Gyr) stellar populations.…”

Section: Introductionmentioning

confidence: 99%

Stellar population analysis from broad-band colours

Abdel-Hamid

Notni

2000

Astron. Nachr.

Self Cite

View full text Add to dashboard Cite

We have developed an analytical method to investigate the stellar populations in a galaxy using the broad-band colours. The method enables us to determine the relative contribution, spatial distribution and age for different stellar populations and gives a hint about the dust distribution in a galaxy. We apply this method to the irregular galaxy NGC 3077, using CCD images in U, B , V and R filters.

show abstract

The Central Regions of M82 – Scattered Light and Extinction

Cited by 11 publications

References 22 publications

Young stars in the disk of M82

Young stars in the disk of M82

The Optical Structure of the Starburst Galaxy M82. I. Dynamics of the Disk and Inner-Wind

Stellar population analysis from broad-band colours

Contact Info

Product

Resources

About