Neutral hydrogen associated with shells and other fine structure in NGC 2865: A dynamically young elliptical?

Schiminovich, David; Vangorkom, Jh; Vanderhulst, Jm; Malin, D.

doi:10.1086/187864

Cited by 74 publications

(94 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These two features are typically associated with galaxy interactions. Stellar spectroscopy and UBV photometry set lower and upper limits to the age of the possible encounter to 1 and 4 Gyr respectively, which is consistent with major merger models (Schiminovich et al 1995). This encounter would have lead to the formation of NGC 2865.…”

Section: Introductionsupporting

confidence: 78%

“…In this paper, we study the surroundings of the elliptical galaxy NGC 2865, which has an unusual quantity of HI gas around it (M HI ∼ 1.2 × 10 9 M , Schiminovich et al 1995). The galaxy NGC 2865 is classified as an E3 in the RC3 catalog (de Vaucouleurs et al 1991), and it satisfies the Faber & Jackson (1976) relation (Lake & Dressler 1986).…”

Section: Introductionmentioning

confidence: 99%

“…(b) The central velocity dispersion σ C was taken from Hau et al (1999). (c) Taken from Schiminovich et al (1995).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A census of Hαemitters in the intergalactic medium of the NGC 2865 system

Urrutia-Viscarra

Arnaboldi

Oliveira

et al. 2014

A&A

View full text Add to dashboard Cite

Tidal debris, which are rich in HI gas and formed in interacting and merging systems, are suitable laboratories to study star formation outside galaxies. Recently, several such systems were observed, which contained many young star forming regions outside the galaxies. In previous works, we have studied young star forming regions outside galaxies in different systems with optical and/or gaseous tidal debris, in order to understand how often they occur and in which type of environments. In this paper, we searched for star forming regions around the galaxy NGC 2865, a shell galaxy that is circled by a ring of HI with a total mass of 1.2×10 9 M . Using the multi-slit imaging spectroscopy technique with the Gemini telescope, we detected all Hα emitting sources in the surroundings of the galaxy NGC 2865, down to a flux limit of 10 −18 erg cm −2 s −1 Å −1 . With the spectra information and the near and far-ultraviolet flux, we characterize the star formation rates, masses, ages, and metallicities for these HII regions. In total, we found 26 emission-line sources in a 60 × 60 Kpc field centered over the southeastern tail of the HI gas present around the galaxy NGC 2865. Out of the 26 Hα emitters, 19 are in the satellite galaxy FGCE 0745, and seven are intergalactic HII regions scattered over the south tail of the HI gas around NGC 2865. We found that the intergalactic HII regions are young (<200 Myr) with stellar masses in the range 4 × 10 3 M to 17 × 10 6 M . These are found in a region of low HI gas density, where the probability of forming stars is expected to be low. For one of the intergalactic HII regions, we estimated a solar oxygen abundance of 12 + log(O/H) ∼ 8.7. We also were able to estimate the metallicity for the satellite galaxy FGCE 0745 to be 12 + log(O/H) ∼ 8.0. Given these physical parameters, the intergalactic HII regions are consistent with young star forming regions (or clusters), which are born in situ outside the NGC 2865 galaxy from a pre-enriched gas removed from the host galaxies in a merger event. The relevance of these observations is discussed.

show abstract

Section: Introductionsupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A census of Hαemitters in the intergalactic medium of the NGC 2865 system

Urrutia-Viscarra

Arnaboldi

Oliveira

et al. 2014

A&A

View full text Add to dashboard Cite

show abstract

“…This blue colour is related a young stellar population (0.4-1.7 Gyr) which forms a KDC (Hau et al 1999). NGC 2865 also contains an incomplete HI disk (Schiminovich et al 1995). An interesting result is that a bright HI patch is coinciding with a bright shell observed earlier (labelled as shell 2 in this work and called shell 2B by Fort et al 1986).…”

Section: Ngc 2865mentioning

confidence: 99%

“…Observational evidence for significant amounts of dust residing in a shell was found in NGC 5128 (Stickel et al 2004). HI gas in shells has been found in M 83, NGC 2865 and NGC 3656 (Schiminovich et al 1995;Balcells et al 2001). A third, speculative, idea explaining the presence dust in shells, is that dust is swept up by the shell stars as they pass through the potential of the galaxy.…”

Section: Shell Coloursmentioning

confidence: 99%

HST/ACS observations of shell galaxies: inner shells, shell colours and dust

Sikkema

Carter²,

Peletier

et al. 2007

A&A

View full text Add to dashboard Cite

Context. Shells in Elliptical Galaxies are faint, sharp-edged features, believed to provide evidence for a merger event. Accurate photometry at high spatial resolution is needed to learn on presence of inner shells, population properties of shells, and dust in shell galaxies. Aims. Learn more about the origin of shells and dust in early type galaxies. Methods. V − I colours of shells and underlying galaxies are derived, using HST Advanced Camera for Surveys (ACS) data. A galaxy model is made locally in wedges and subtracted to determine shell profiles and colours. We applied Voronoi binning to our data to get smoothed colour maps of the galaxies. Comparison with N-body simulations from the literature gives more insight to the origin of the shell features. Shell positions and dust characteristics are inferred from model galaxy subtracted images. Results. The ACS images reveal shells well within the effective radius in some galaxies (at 0.24 r e = 1.7 kpc in the case of NGC 5982). In some cases, strong nuclear dust patches prevent detection of inner shells. Most shells have colours which are similar to the underlying galaxy. Some inner shells are redder than the galaxy. All six shell galaxies show out of dynamical equilibrium dust features, like lanes or patches, in their central regions. Our detection rate for dust in the shell ellipticals is greater than that found from HST archive data for a sample of normal early-type galaxies, at the 95% confidence level.Conclusions. The merger model describes better the shell distributions and morphologies than the interaction model. Red shell colours are most likely due to the presence of dust and/or older stellar populations. The high prevalence and out of dynamical equilibrium morphologies of the central dust features point towards external influences being responsible for visible dust features in early type shell galaxies. Inner shells are able to manifest themselves in relatively old shell systems.

show abstract

BV photometry of five shell galaxies

Pierfederici¹,

Rampazzo

2004

Astron Nachr

View full text Add to dashboard Cite

Abstract. Current views consider shell structures as bona fide signatures of a recent minor/major merging event though also weak interaction models (WIM) could produce long lasting shells on host galaxies possessing a stellar thick disc. We present a B V band photometric study of a sample of 5 shell galaxies belonging to the Malin & Carter (1983) compilation. The structural properties and colors of the galaxies, as well as the colors of their shells are examined in detail. We did not find signatures of the presence of double nuclei. NGC 7585 is the only E galaxy in the sample and has a moderately boxy structure. The other galaxies have either a discy structure or are mixed E/S0 type galaxies. NGC 474 is a true lenticular. NGC 6776 shows a diffuse asymmetric outer structure and a system of tails of the the same color of the galaxy body; but not clear shells. In general, the color of the shells in our sample is similar or slightly redder than that of the host galaxy, whose color, in turn, is typical of the early-type morphological class. One of the outer shells of NGC 474 is significantly bluer than the body of the galaxy. Since NGC 474 appears to be interacting with NGC 470, the color of this one shell could be explained as result of a recent acquisition of material through tidal interaction. The WIM hypothesis could explain both the red and the blue shells of NGC 474, this latter acquired from the fly-by of the nearby companion NGC 470, but the lack of the constancy of shell surface brightness as a ratio of the underlying galaxy brightness argues against WIM. We speculate about evidence, which also comes from different observations, that suggests a merging/accretion origin of the shells.

show abstract

Neutral hydrogen associated with shells and other fine structure in NGC 2865: A dynamically young elliptical?

Cited by 74 publications

References 0 publications

A census of Hαemitters in the intergalactic medium of the NGC 2865 system

A census of Hαemitters in the intergalactic medium of the NGC 2865 system

HST/ACS observations of shell galaxies: inner shells, shell colours and dust

BV photometry of five shell galaxies

Contact Info

Product

Resources

About