Resolving stellar populations outside the Local Group: MAD observations of UKS 2323-326

Gullieuszik, Marco; Greggio, L.; Held, E. V.; Moretti, Alessia; Arcidiacono, Carmelo; Bagnara, Paolo; Baruffolo, A.; Diolaiti, Emiliano; Falomo, R.; Farinato, Jacopo; Lombini, Matteo; Ragazzoni, Roberto; Brast, R.; Donaldson, Rob; Kolb, Johann; Marchetti, Enrico; Tordo, Sebastien

doi:10.1051/0004-6361:200809631

Cited by 19 publications

(25 citation statements)

References 22 publications

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“…Observationally, however, our task was somewhat more difficult. On the one hand, NGC5128 is by a factor of ∼ 1.5 − 2 more distant than UKS 2323-326, while on the other, the observations of Gullieuszik et al (2008) were by a factor of ∼ 3 − 4 deeper 18 than our Subaru data. This is easily visible on the CMD of Fig.…”

Section: Resolving Extra-galactic Stars Beyond Our Lgcontrasting

confidence: 65%

High-resolution Observations of Cen A: Yellow and Red Supergiants in a Region of Jet-induced Star Formation?*

Markakis¹,

Eckart²,

Castro³

et al. 2018

ApJ

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We present the analysis of near infrared (NIR), adaptive optics (AO) Subaru and archived HST imaging data of a region near the northern middle lobe (NML) of the Centaurus A (Cen A) jet, at a distance of ∼ 15 kpc north-east (NE) from the center of NGC5128. Low-pass filtering of the NIR images reveals strong -> 3σ above the background mean -signal at the expected position of the brightest star in the equivalent HST field. Statistical analysis of the NIR background noise suggests that the probability to observe > 3σ signal at the same position, in three independent measurements due to stochastic background fluctuations alone is negligible (≤ 10 −7 %) and, therefore, that this signal should reflect the detection of the NIR counterparts of the brightest HST star. An extensive photometric analysis of this star yields V − I, visual-NIR, and NIR colors expected from a yellow supergiant (YSG) with an estimated age ∼ 10 +4 −3 Myr. Furthermore, the second and third brighter HST stars are, likely, also supergiants in Cen A, with estimated ages ∼ 16 +6 −3 Myr and ∼ 25 +15 −9 Myr, respectively. The ages of these three supergiants are in good agreement with the ages of the young massive stars that were previously found in the vicinity and are thought to have formed during the later phases of the jet-HI cloud interaction that appears to drive the star formation (SF) in the region for the past ∼ 100 Myr.

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Section: Resolving Extra-galactic Stars Beyond Our Lgcontrasting

confidence: 65%

High-resolution Observations of Cen A: Yellow and Red Supergiants in a Region of Jet-induced Star Formation?*

Markakis¹,

Eckart²,

Castro³

et al. 2018

ApJ

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“…1.4, and confirmed in the near-infrared, SagDIG study of Gullieuszik et al (2008). Battinelli & Demers (2005b) address the standard candle aspect of carbon stars and conclude that their average M I luminosity is viable as long as the parent galaxy contains some hundred C stars or more.…”

Section: Carbon-rich Starsmentioning

confidence: 83%

The H i hole and AGB stellar population of the Sagittarius dwarf irregular galaxy

Momany

Clemens

Bedin

et al. 2014

A&A

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Using two HST/ACS data sets that are separated by about two years has allowed us to derive the relative proper motion for the Sagittarius dwarf irregular (SagDIG) and reduce the heavy foreground Galactic contamination. The proper-motion decontaminated SagDIG catalog provides a much clearer view of the young red-supergiant and intermediate-age asymptotic giant branch populations. Previously identified carbon-and oxygen-rich star samples, which are based on narrow-band filter photometry, were complemented by membership criteria. We report identifying three Milky Way carbon-rich dwarf stars, which probably belong to the thin disk, and pointing to the high incidence of this class at low Galactic latitudes. A subgroup of four oxygen-rich candidate stars depicts a faint, red extension of the well-defined SagDIG carbon-rich sequence. The origin of these oxygen-rich candidate stars remains unclear, reflecting the uncertainty in the ratio of carbon-and oxygen-rich stars. Finally, SagDIG is a gas-rich galaxy characterized by a single large cavity in the gas disk (H  hole), which is offset by ∼360 pc from the optical center of the galaxy. We nonetheless investigate the stellar feedback hypothesis by comparing the proper-motion cleaned stellar populations within the H  hole with appropriately selected comparison regions that have higher H  densities external to the hole. The comparison shows no significant differences. In particular, the center of the H  hole (and the comparison regions) lack stellar populations younger than ∼400 Myr, which are otherwise abundant in the inner body of the galaxy. We conclude that there is no convincing evidence that the SagDIG H  hole is the result of stellar feedback and that gravitational and thermal instabilities in the gas are the most likely mechanism for its formation.

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“…In this mode MAD is equipped with three optical ShackHartmann wavefront sensors to measure the atmospheric turbulence from three guide stars located, ideally, at the vertexes of an equilateral triangle within a field of 2 arcmin diameter. MAD has also a "layer-oriented" wavefront sensing mode, built by INAF, and this mode may use up to 8 natural guide stars, which can be fainter than the guide stars in the star-oriented mode (see Momany et al 2008;Gullieuszik et al 2008;Moretti et al 2009, for details). This mode was not offered for science demonstration observations.…”

Section: Mad Observationsmentioning

confidence: 99%

MAD about the Large Magellanic Cloud

Fiorentino

Tolstoy

Diolaiti

et al. 2011

A&A

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We present J, H, K s photometry from the the Multi conjugate Adaptive optics Demonstrator (MAD), a visitor instrument at the VLT, of a resolved stellar population in a small crowded field in the bar of the Large Magellanic Cloud near the globular cluster NGC 1928. In a total exposure time of 6, 36 and 20 min, magnitude limits were achieved of J ∼ 20.5 mag, H ∼ 21 mag, and K s ∼ 20.5 mag respectively, with S /N > 10. This does not reach the level of the oldest Main Sequence Turnoffs, however the resulting ColourMagnitude Diagrams are the deepest and most accurate obtained so far in the infrared for the LMC bar. We combined our photometry with deep optical photometry from the Hubble Space Telescope/Advanced Camera for Surveys, which is a good match in spatial resolution. The comparison between synthetic and observed CMDs shows that the stellar population of the field we observed is consistent with the star formation history expected for the LMC bar, and that all combinations of IJHK s filters can, with some care, produce the same results. We used the red clump magnitude in K s to confirm the LMC distance modulus as, μ 0 = 18.50 ± 0.06 r ± 0.09 s mag. We also addressed a number of technical aspects related to performing accurate photometry with adaptive optics images in crowded stellar fields, which has implications for how we should design and use the Extremely Large Telescopes of the future for studies of this kind.

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Resolving stellar populations outside the Local Group: MAD observations of UKS 2323-326

Cited by 19 publications

References 22 publications

High-resolution Observations of Cen A: Yellow and Red Supergiants in a Region of Jet-induced Star Formation?*

High-resolution Observations of Cen A: Yellow and Red Supergiants in a Region of Jet-induced Star Formation?*

The H i hole and AGB stellar population of the Sagittarius dwarf irregular galaxy

MAD about the Large Magellanic Cloud

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