An H i threshold for star cluster formation in tidal debris*

Maybhate, A.; Masiero, J.; Hibbard, J. E.; Charlton, Jane C.; Palma, Christopher; Knierman, Karen; English, Jayanne

doi:10.1111/j.1365-2966.2007.12265.x

Cited by 31 publications

(61 citation statements)

References 38 publications

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“…However, in all of these cases, the recent star formation has occurred in areas with higher H i column densities (N H i > 4 − 8 × 10 20 cm −2 ) than that observed in our field, and is thus consistent with the lack of recent (i.e., τ 10 8 yr) star formation in our field. This is also consistent with the findings of Maybhate et al (2007), who find recent lowlevel star formation at levels N H i ∼ 4×10 20 cm −2 ). We note that while recent episodes of star formation in the outermost regions of late-types galaxies have been observed at column densities similar to that in our field (∼10 20 cm −2 ; e.g., de Blok & Walter 2003;Thilker et al 2007), we do not see evidence of this in our (small) field.…”

Section: Blue Starssupporting

confidence: 82%

DEEPHST/ACS PHOTOMETRY OF THE M81 HALO

Durrell

Sarajedini

Chandar

2010

ApJ

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We present a deep color-magnitude diagram (CMD) for individual stars in the halo of the nearby spiral galaxy M81, at a projected distance of 19 kpc, based on data taken with the Advanced Camera for Surveys on the Hubble Space Telescope (HST). The CMD reveals a red giant branch (RGB) that is narrow and fairly blue, and a horizontal branch that has stars that lie mostly redward of the RR Lyrae instability strip. We derive a mean metallicity of [M/H] = −1.15 ± 0.11 and age of 9 ± 2 Gyr for the dominant population in our field, from the shape of the RGB, the magnitude of the red clump, and the location of the RGB bump. We compare our metallicity and age results with those found previously for stars in different locations within M81 and in the spheroids of other nearby galaxies.

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Section: Blue Starssupporting

confidence: 82%

DEEPHST/ACS PHOTOMETRY OF THE M81 HALO

Durrell

Sarajedini

Chandar

2010

ApJ

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“…Toomre & Toomre 1972. In this sense Maybhate et al (2007) studied star clusters in interacting galaxies. They used 21 cm Hi maps and the Hubble Space Telescope Wide Field Planetary Camera 2.…”

Section: The Evolutionary Stage Of Ngc 6845mentioning

confidence: 99%

“…These authors studied the relation between the formation of star clusters and the Hi column density. The study performed by Maybhate et al (2007) reveals that the star clusters are formed in regions with log(NHI )≥ 20.6 cm −2 . According to the above the Hi emission in NGC 6845 is log(NHI )∼20.8 cm −2 (see Gordon et al 2003), this value is higher than the threshold proposed by Maybhate et al (2007) for the formation of star clusters in debris of tidal interactions.…”

Section: The Evolutionary Stage Of Ngc 6845mentioning

confidence: 99%

“…The study performed by Maybhate et al (2007) reveals that the star clusters are formed in regions with log(NHI )≥ 20.6 cm −2 . According to the above the Hi emission in NGC 6845 is log(NHI )∼20.8 cm −2 (see Gordon et al 2003), this value is higher than the threshold proposed by Maybhate et al (2007) for the formation of star clusters in debris of tidal interactions. Smith et al (2008), Bastian et al (2009) and TorresFlores et al (2014) have studied the ages of star-forming regions in interacting galaxies (NGC 2856/4, NGC 4038/9 and NGC 92, respectively).…”

Section: The Evolutionary Stage Of Ngc 6845mentioning

confidence: 99%

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NGC 6845: metallicity gradients and star formation in a complex compact group

Olave-Rojas

Torres-Flores

Carrasco

et al. 2015

Mon. Not. R. Astron. Soc.

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We have obtained Gemini/GMOS spectra of 28 regions located across the interacting group NGC 6845, spanning from the inner regions of the four major galaxies (NGC 6845A, B, C, D) to the tidal tails of NGC 6845A. All regions in the tails are starforming objects with ages younger than 10 Myr. We derived the gas-phase metallicity gradients across NGC 6845A and its two tails and we find that these are shallower than those for isolated galaxies. NGC 6845A has a gas-phase oxygen central metallicity of 12+log(O/H)∼8.5 and a flat gas-phase metallicity gradient (β=0.002±0.004 dex kpc −1 ) out to ∼4 × R 25 (to the end of the longest tidal tail). Considering the mass-metallicity relation, the central region of NGC 6845A displays a lower oxygen abundance than the expected for its mass. Taking into account this fact and considering the flat oxygen distribution measured along the eastern tidal tail, we suggest that an interaction event has produced a dilution in the central metallicity of this galaxy and the observed flattening in its metal distribution. We found that the star formation process along the eastern tidal structure has not been efficient enough to increase the oxygen abundances in this place, suggesting that this structure was formed from enriched material.

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“…All these regions are located in low-density of HI gas (HI ≥ 10 19 cm −2 , Schiminovich et al 1995), where the probability of forming stars is low, in general (Maybhate et al 2007). …”

Section: Intergalactic Hii Regionsmentioning

confidence: 99%

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

Urrutia-Viscarra

Arnaboldi

Oliveira

et al. 2014

A&A

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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.

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An H i threshold for star cluster formation in tidal debris*

Cited by 31 publications

References 38 publications

DEEPHST/ACS PHOTOMETRY OF THE M81 HALO

DEEPHST/ACS PHOTOMETRY OF THE M81 HALO

NGC 6845: metallicity gradients and star formation in a complex compact group

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

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