Redshift observations in the Hydra-Centaurus region

Fairall, A. P.; Willmer, C. N. A.; Calderón, J. H.; Latham, David W.; Costa, L. N. da; Pellegrini, P. S.; Nunes, Miguel; Focardi, P.; Vettolani, G.

doi:10.1086/116037

Cited by 26 publications

(16 citation statements)

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“…4). UGC 8939, whose redshift is already known (z = 0.0248, Fairall et al 1992), we identify with the stronger, less redshifted line. One might expect a signal from MCG+00-36-011, but this galaxy has a redshift of 0.0249 and may blend with the signal from UGC 8939; also because it is located just outside the FWHM circle and because elliptical galaxies in general show much weaker H I emission than spirals or irregulars we conclude that this galaxy was entirely not detected or is at least only very slightly affecting the detection of UGC 8939.…”

Section: H I Spectroscopymentioning

confidence: 63%

Supernovae without host galaxies?

Zinn

Stritzinger

Braithwaite

et al. 2012

A&A

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Context. A remarkable fraction of supernovae (SNe) have no obvious host galaxy. Two possible explanations are that (i) the host galaxy is simply not detected within the sensitivity of the available data or that (ii) the progenitor is a hypervelocity star that has escaped its parent galaxy. Aims. We use the Type IIb SN 2009Z as a prototype of case (i), an example of how a very faint (here low surface brightness; LSB) galaxy can be discovered via the observation of a seemingly host-less SN. By identifying and studying LSB galaxies that host SNe related to the death of massive stars, we can place constraints on the stellar population and environment of LSB galaxies, which at present are poorly understood. Methods. We use archival ultraviolet (UV) and optical imaging, as well as an H I spectrum taken with the 100 m Effelsberg Radio Telescope to measure various parameters of the host galaxy, in particular its redshift, stellar and H I mass, and metallicity. Results. From the Effelsberg spectrum, a redshift z = 0.02513 ± 0.00001 and an H I mass of 2.96 ± 0.12 × 10 9 M are computed. This redshift is consistent with that obtained from optical emission lines of SN 2009Z. Furthermore, a gas mass fraction of f g = 0.87±0.04 is obtained, one of the highest fractions ever measured. The host galaxy shows signs of recently enhanced star formation activity with a far-UV derived extinction-corrected star formation rate (SFR) of 0.44 ± 0.34 M yr −1 . Based on the B-band luminosity we estimate an extinction-corrected metallicity following the calibration by Pilyugin (2001) of 12 + log O H = 8.24 ± 0.70. Conclusions. The presence of a Type IIb SN in an LSB galaxy suggests, contrary to popular belief, that massive stars can be formed in this type of galaxies. Furthermore, our results imply that LSB galaxies undergo phases of small, local burst activity intermittent with longer phases of inactivity, rather than a continuous but very low SFR. Discovering faint (LSB) galaxies via bright supernova events happening in them offers an excellent opportunity to improve our understanding of the nature of LSB galaxies.

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Section: H I Spectroscopymentioning

confidence: 63%

Supernovae without host galaxies?

Zinn

Stritzinger

Braithwaite

et al. 2012

A&A

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“…In fact, Cellone et al (1994) noted that the two largest photographic surveys in the Fornax Cluster (namely those by Davies et al 1988 and Notes. a v r from Fairall et al (1992). b v r from Huchra et al (1983).…”

Section: Nucleated Dwarfsmentioning

confidence: 99%

The low-luminosity galaxy population in the NGC 5044 Group

Cellone

Buzzoni

2005

Monthly Notices of the Royal Astronomical Society

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We present multicolour imaging for 33 dwarf and intermediate-luminosity galaxies in the field of the NGC 5044 Group, complemented with mid-resolution spectroscopy for a subsample of 13 objects. With these data, a revised membership and morphological classification is made for the galaxies in the sample. We were able to confirm all but one of the "definite members" included in the spectroscopic subsample, which were originally classified based on morphological criteria; however, an important fraction of background galaxies is probably present among "likely" and "possible" members. The presence of a nucleus could be detected in just five out of the nine galaxies originally classified as dE,N, thus confirming the intrisic difficulty of photographic-plate morphological classification for this kind of object. Our deep surface photometry provided clear evidences for disc structure in at least three galaxies previously catalogued as dE or dS0. Their transition-type properties are also evident from the colour-magnitude diagram, where they lie near the late-type galaxies locus, suggesting an evolutionary connection between a parent disc-galaxy population and at least part of present-day dEs. Six new dSph candidates were also found, most of them at small projected distances from NGC 5044, the central galaxy of the Group. The NGC 5044 Group appears clearly defined in redshift space, with a mean heliocentric radial velocity, =2461 +/- 84 km/s (z=0.0082), and a moderate dispersion, \sigma_{v_r}=431 km/s. Our data show no luminosity segregation for early-type galaxies: both dwarf and bright E/S0 systems show very similar velocity distributions (\sigma_{v_r} ~ 290 km/s), in contrast to late-type galaxies that seem to display a broader distribution (\sigma_{v_r} ~ 680 km/s).Comment: 12 pages, 6 figures, uses mn2e.cls. To be published in MNRAS. For more info, full-resolution paper and colour figures see http://www.bo.astro.it/~eps/home.htm

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“…ii) Tully (1988); j) Richter et al (1987); k) Davies et al (1989); l) de Vaucouleurs et al (1991), ll) Thuan et al (1981); m) Strauss et al (1992); n) Fairall et al (1988); o) Staveley-Smith et al (1987); p) Dressler et al (1991); q) Fairall et al (1991); r) Chengalur et al (1993); s) Tifft et al (1988); t) Giovanelli et al (1997); u) Fairall et al (1992); v) Bottinelli et al (1993); w) Loveday et al (1996); 1) Mathewson et al (1992);…”

Section: Optical Dataunclassified

Warps and correlations with intrinsic parameters of galaxies in the visible and radio

Castro-Rodríguez

López-Corredoira

Sánchez-Saavedra

et al. 2002

A&A

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Abstract. From a comparison of the different parameters of warped galaxies in the radio, and especially in the visible, we find that: a) No large galaxy (large mass or radius) has been found to have high amplitude in the warp, and there is no correlation of size/mass with the degree of asymmetry of the warp. b) The disc density and the ratio of dark to luminous mass show an opposing trend: smaller values give more asymmetric warps in the inner radii (optical warps) but show no correlation with the amplitude of the warp; however, in the external radii is there no correlation with asymmetry. c) A third anticorrelation appears in a comparison of the amplitude and degree of asymmetry in the warped galaxies. Hence, it seems that very massive dark matter haloes have nothing to do with the formation of warps but only with the degree of symmetry in the inner radii, and are unrelated to the warp shape for the outermost radii. Denser discs show the same dependence.

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Redshift observations in the Hydra-Centaurus region

Cited by 26 publications

References 0 publications

Supernovae without host galaxies?

Supernovae without host galaxies?

The low-luminosity galaxy population in the NGC 5044 Group

Warps and correlations with intrinsic parameters of galaxies in the visible and radio

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