The STREGA survey – II. Globular cluster Palomar 12★

Musella, I.; Criscienzo, M. Di; Marconi, M.; Raimondo, Gabriella; Ripepi, V.; Cignoni, M.; Bono, G.; Brocato, E.; Dall’Ora, M.; Ferraro, I.; Grado, A.; Iannicola, G.; Limatola, L.; Molinaro, R.; Moretti, M. I.; Stetson, P. B.; Capaccioli, M.; Cioni, M. R. L.; Getman, F.; Schipani, P.

doi:10.1093/mnras/stx2543

Cited by 12 publications

(8 citation statements)

References 49 publications

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“…More recent measurements of Pal 12 byMusella et al (2018) indicate a smaller half-light radius of 5.4 pc and attribute the larger size found previously to contamination from the Sagittarius stream.…”

supporting

confidence: 49%

Eridanus II: A Fossil from Reionization with an Off-center Star Cluster

Simon

Brown

Drlica-Wagner

et al. 2021

ApJ

124

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We present deep Hubble Space Telescope (HST) photometry of the ultra-faint dwarf galaxy Eridanus II (Eri II). Eri II, which has an absolute magnitude of M V = −7.1, is located at a distance of 339 kpc, just beyond the virial radius of the Milky Way. We determine the star formation history of Eri II and measure the structure of the galaxy and its star cluster. We find that a star formation history consisting of two bursts, constrained to match the spectroscopic metallicity distribution of the galaxy, accurately describes the Eri II stellar population. The best-fit model implies a rapid truncation of star formation at early times, with >80% of the stellar mass in place before z ∼ 6. A small fraction of the stars could be as young as 8 Gyr, but this population is not statistically significant; Monte Carlo simulations recover a component younger than 9 Gyr only 15% of the time, where they represent an average of 7 ± 4% of the population. These results are consistent with theoretical expectations for quenching by reionization. The HST depth and angular resolution enable us to show that Eri II’s cluster is offset from the center of the galaxy by a projected distance of 23 ± 3 pc. This offset could be an indication of a small (∼50–75 pc) dark matter core in Eri II. Moreover, we demonstrate that the cluster has a high ellipticity of and is aligned with the orientation of Eri II within 3° ± 6°, likely due to tides. The stellar population of the cluster is indistinguishable from that of Eri II itself.

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supporting

confidence: 49%

Eridanus II: A Fossil from Reionization with an Off-center Star Cluster

Simon

Brown

Drlica-Wagner

et al. 2021

ApJ

124

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“…Relatively metal rich clusters show a small dispersion and an average [Y/Fe] abundance close to solar, with the exception of the outer Halo cluster Pal 12. The peculiarity of this cluster is not surprising, since there are photometric and spectroscopic reasons to believe that Pal 12 is an accreted cluster (Musella et al 2018, and 15), but ones in clusters do not (Figure 14). The metal-rich RRLs mainly come from the dataset collected by Liu et al (2013), with the exception of two stars provided by Clementini et al (1995) 11).…”

Section: S-process Element: Yttriummentioning

confidence: 93%

Chemical Compositions of Field and Globular Cluster RR Lyrae Stars. I. NGC 3201^∗

Magurno

Sneden

Braga

et al. 2018

ApJ

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We present a detailed spectroscopic analysis of horizontal branch stars in the globular cluster NGC 3201. We collected optical (4580-5330Å), high resolution (∼34,000), high signal-to-noise ratio (∼200) spectra for eleven RR Lyrae stars and one red horizontal branch star with the multifiber spectrograph M2FS at the 6.5m Magellan telescope at the Las Campanas Observatory. From measured equivalent widths we derived atmospheric parameters and abundance ratios for α (Mg, Ca, Ti), iron peak (Sc, Cr, Ni, Zn) and s-process (Y) elements. We found that NGC 3201 is a homogeneous, monometallic ([Fe/H]=−1.47 ± 0.04), α-enhanced ([α/Fe]=0.37 ± 0.04) cluster. The relative abundances of the iron peak and s-process elements were found to be consistent with solar values. In comparison with other large stellar samples, NGC 3201 RR Lyraes have similar chemical enrichment histories as do those of other old (t≥10 Gyr) Halo components (globular clusters, red giants, blue and red horizontal branch stars, RR Lyraes). We also provided a new average radial velocity estimate for NGC 3201 by using a template velocity curve to overcome the limit of single epoch measurements of variable stars: V rad = 494 ± 2 km s −1 (σ=8 km s −1 ).

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“…The adoption of this additional selection cut to the GCs sample leaves us with just the four main body clusters; however the membership of Pal 12 to the trailing arm, for instance, is confirmed by matching the orbit, detection of stream stars in the surroundings, and chemical tagging (see e.g. Sohn et al 2018;Vasiliev 2019;Musella et al 2018;Cohen 2004, and references therein). The set of criteria adopted in this work allowed us to trace very clearly the youngest stream arms while leaving open the possibility for the tentative detection of older structures.…”

Section: Adopted Samplesmentioning

confidence: 99%

Globular clusters in the Sagittarius stream

Bellazzini¹,

Ibata

Malhan

et al. 2020

A&A

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We reconsider the case for the association of Galactic globular clusters to the tidal stream of the Sagittarius dwarf spheroidal galaxy (Sgr dSph) using Gaia DR2 data. We used RR Lyrae variables to trace the stream in 6D and we selected clusters matching the observed stream in position and velocity. In addition to the clusters residing in the main body of the galaxy (M 54, Ter 8, Ter 7, Arp 2) we confirm the membership of Pal 12 and Whiting 1 to the portion of the trailing arm populated by stars lost during recent perigalactic passages. NGC 2419, NGC 5634, and NGC 4147 are very interesting candidates, possibly associated with more ancient wraps of the Sagittarius stream. With the exception of M 54, which lies within the stellar nucleus of the galaxy, we note that all these clusters are found in the trailing arm of the stream. The selected clusters are fully consistent with the [Fe/H] versus [Mg/Fe], [Ca/Fe] patterns and the age-metallicity relation displayed by field stars in the main body of Sgr dSph.

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The STREGA survey – II. Globular cluster Palomar 12★

Cited by 12 publications

References 49 publications

Eridanus II: A Fossil from Reionization with an Off-center Star Cluster

Eridanus II: A Fossil from Reionization with an Off-center Star Cluster

Chemical Compositions of Field and Globular Cluster RR Lyrae Stars. I. NGC 3201^∗

Globular clusters in the Sagittarius stream

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The STREGA survey – II. Globular cluster Palomar 12★

Cited by 12 publications

References 49 publications

Eridanus II: A Fossil from Reionization with an Off-center Star Cluster

Eridanus II: A Fossil from Reionization with an Off-center Star Cluster

Chemical Compositions of Field and Globular Cluster RR Lyrae Stars. I. NGC 3201∗

Globular clusters in the Sagittarius stream

Contact Info

Product

Resources

About

Chemical Compositions of Field and Globular Cluster RR Lyrae Stars. I. NGC 3201^∗