The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Anne Dutrey - One of the best experts on this subject based on the ideXlab platform.
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possible planet formation in the young low mass multiple Stellar System gg tau a
Nature, 2014Co-Authors: Anne Dutrey, Emmanuel Di Folco, S Guilloteau, Yann Boehler, Jeffrey S Bary, Tracy L Beck, Herve BeustAbstract:Investigation of the triple Stellar System GG Tau A reveals gas fragments within the central cavity between the Keplerian outer ring orbiting the entire System and the stars themselves; gas flow from this outer ring appears capable of sustaining the inner disk surrounding component star GG Tau Aa beyond the accretion lifetime, leaving time for planet formation to occur. Atacama Large Millimetre Array (ALMA) observations of G GTau A, one of the most intensively studied Stellar Systems, reveal a flow of fresh material that would make planet formation possible even in the unstable environment of young binary star Systems. This flow had previously been predicted by numerical simulation, but not confirmed observationally. New images show gas fragments traced by carbon monoxide emission within the GG Tau A cavity. Kinematic analysis suggests that the flow is capable of sustaining the inner disk around GG Tau Aa beyond the accretion lifetime, leaving sufficient time to allow planet formation. The formation of planets around binary stars may be more difficult than around single stars1,2,3. In a close binary star (with a separation of less than a hundred astronomical units), theory predicts the presence of circumStellar disks around each star, and an outer circumbinary disk surrounding a gravitationally cleared inner cavity around the stars4,5. Given that the inner disks are depleted by accretion onto the stars on timescales of a few thousand years, any replenishing material must be transferred from the outer reservoir to fuel planet formation (which occurs on timescales of about one million years). Gas flowing through disk cavities has been detected in single star Systems6. A circumbinary disk was discovered around the young low-mass binary System GG Tau A (ref. 7), which has recently been shown to be a hierarchical triple System8. It has one large inner disk9 around the single star, GG Tau Aa, and shows small amounts of shocked hydrogen gas residing within the central cavity10, but other than a single weak detection11, the distribution of cold gas in this cavity or in any other binary or multiple star System has not hitherto been determined. Here we report imaging of gas fragments emitting radiation characteristic of carbon monoxide within the GG Tau A cavity. From the kinematics we conclude that the flow appears capable of sustaining the inner disk (around GG Tau Aa) beyond the accretion lifetime, leaving time for planet formation to occur there. These results show the complexity of planet formation around multiple stars and confirm the general picture predicted by numerical simulations.
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Possible planet formation in the young, low-mass, multiple Stellar System GG Tau A
Nature, 2014Co-Authors: Anne Dutrey, Emmanuel Di Folco, S Guilloteau, Yann Boehler, Herve Beust, Jeff Bary, Tracy Beck, E. Chapillon, Fredéric Gueth, J.-m. HuréAbstract:The formation of planets around binary stars may be more difficult than around single stars1, 2, 3. In a close binary star (with a separation of less than a hundred astronomical units), theory predicts the presence of circumStellar disks around each star, and an outer circumbinary disk surrounding a gravitationally cleared inner cavity around the stars4, 5. Given that the inner disks are depleted by accretion onto the stars on timescales of a few thousand years, any replenishing material must be transferred from the outer reservoir to fuel planet formation (which occurs on timescales of about one million years). Gas flowing through disk cavities has been detected in single star Systems6. A circumbinary disk was discovered around the young low-mass binary System GG Tau A (ref. 7), which has recently been shown to be a hierarchical triple System8. It has one large inner disk9 around the single star, GG Tau Aa, and shows small amounts of shocked hydrogen gas residing within the central cavity10, but other than a single weak detection11, the distribution of cold gas in this cavity or in any other binary or multiple star System has not hitherto been determined. Here we report imaging of gas fragments emitting radiation characteristic of carbon monoxide within the GG Tau A cavity. From the kinematics we conclude that the flow appears capable of sustaining the inner disk (around GG Tau Aa) beyond the accretion lifetime, leaving time for planet formation to occur there. These results show the complexity of planet formation around multiple stars and confirm the general picture predicted by numerical simulations.
F R Ferraro - One of the best experts on this subject based on the ideXlab platform.
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the age of the young bulge like population in the Stellar System terzan 5 linking the galactic bulge to the high z universe
The Astrophysical Journal, 2016Co-Authors: F R Ferraro, B Lanzoni, E Dalessandro, R M Rich, L Origlia, D Massari, A MucciarelliAbstract:The Galactic bulge is dominated by an old, metal-rich Stellar population. The possible presence and the amount of a young (a few gigayears old) minor component is one of the major issues debated in the literature. Recently, the bulge Stellar System Terzan 5 was found to harbor three sub-populations with iron content varying by more than one order of magnitude (from 0.2 up to two times the solar value), with chemical abundance patterns strikingly similar to those observed in bulge field stars. Here we report on the detection of two distinct main-sequence turnoff points in Terzan 5, providing the age of the two main Stellar populations: 12 Gyr for the (dominant) sub-solar component and 4.5 Gyr for the component at super-solar metallicity. This discovery classifies Terzan 5 as a site in the Galactic bulge where multiple bursts of star formation occurred, thus suggesting a quite massive progenitor possibly resembling the giant clumps observed in star-forming galaxies at high redshifts. This connection opens a new route of investigation into the formation process and evolution of spheroids and their Stellar content. Based on data obtained with (1) the ESA/NASA HST, under programs GO-14061, GO-12933, GO-10845, (2) the Very Large Telescope of the European Southern Observatory during the Science Verification of the camera MAD; (3) the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA.
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the binary mass transfer origin of the red blue straggler sequence in m30
The Astrophysical Journal, 2015Co-Authors: F R Ferraro, B Lanzoni, E Dalessandro, P Lu, Licai Deng, G BeccariAbstract:Two separated sequences of blue straggler stars (BSSs) have been revealed by Ferraro et?al. in the color-magnitude diagram (CMD) of the Milky Way globular cluster M30. Their presence has been suggested to be related to the two BSS formation channels (namely, collisions and mass transfer in close binaries) operating within the same Stellar System. The blue sequence was indeed found to be well reproduced by collisional BSS models. In contrast, no specific models for mass-transfer BSSs were available for an old Stellar System like M30. Here we present binary evolution models, including case-B mass transfer and binary merging, specifically calculated for this cluster. We discuss in detail the evolutionary track of a 0.9 + 0.5 M ? binary, which spends approximately 4?Gyr in the BSS region of the CMD of a 13?Gyr old cluster. We also run Monte Carlo simulations to study the distribution of mass-transfer BSSs in the CMD and to compare it with the observational data. Our results show that (1) the color and magnitude distribution of synthetic mass-transfer BSSs defines a strip in the CMD that nicely matches the observed red-BSS sequence, thus providing strong support to the mass-transfer origin for these stars; (2) the CMD distribution of synthetic BSSs never attains the observed location of the blue-BSS sequence, thus reinforcing the hypothesis that the latter formed through a different channel (likely collisions); (3) most (~60%) of the synthetic BSSs are produced by mass-transfer models, while the remaining <40% requires the contribution from merger models.
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ceci n est pas a globular cluster the metallicity distribution of the Stellar System terzan 5
The Astrophysical Journal, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, E Valenti, Rodrigo A Ibata, L LovisiAbstract:We present new determinations of the iron abundance for 220 stars belonging to the Stellar System Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the Very Large Telescope of the European Southern Observatory and DEIMOS at the Keck II Telescope. This is by far the largest spectroscopic sample of stars ever observed in this Stellar System. From this data set, a subsample of targets with spectra unaffected by TiO bands was extracted and statistically decontaminated from field stars. Once combined with 34 additional stars previously published by our group, a total sample of 135 member stars covering the entire radial extent of the System has been used to determine the metallicity distribution function of Terzan 5. The iron distribution clearly shows three peaks: a super-solar component at [Fe/H] ≅ 0.25 dex, accounting for ∼29% of the sample, a dominant sub-solar population at [Fe/H] ≅ –0.30 dex, corresponding to ∼62% of the total, and a minor (6%) metal-poor component at [Fe/H] ≅ –0.8 dex. Such a broad, multi-modal metallicity distribution demonstrates that Terzan 5 is not a genuine globular cluster but the remnant of a much more complex Stellar System.
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ceci n est pas a globular cluster the metallicity distribution of the Stellar System terzan 5
arXiv: Solar and Stellar Astrophysics, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, E Valenti, Rodrigo A Ibata, L LovisiAbstract:We present new determinations of the iron abundance for 220 stars belonging to the Stellar System Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the Very Large Telescope of the European Southern Observatory and DEIMOS at the Keck II Telescope. This is by far the largest spectroscopic sample of stars ever observed in this Stellar System. From this dataset, a subsample of targets with spectra unaffected by TiO bands was extracted and statistically decontaminated from field stars. Once combined with 34 additional stars previously published by our group, a total sample of 135 member stars covering the entire radial extent of the System has been used to determine the metallicity distribution function of Terzan 5. The iron distribution clearly shows three peaks: a super-solar component at [Fe/H]$\simeq0.25$ dex, accounting for 29% of the sample, a dominant sub-solar population at [Fe/H]$\simeq-0.30$ dex, corresponding to 62% of the total, and a minor (6%) metal-poor component at [Fe/H]$\simeq-0.8$ dex. Such a broad, multi-modal metallicity distribution demonstrates that Terzan 5 is not a genuine globular cluster but the remnant of a much more complex Stellar System.
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chemical and kinematical properties of galactic bulge stars surrounding the Stellar System terzan 5
The Astrophysical Journal, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, Rodrigo A Ibata, L Lovisi, M BellazziniAbstract:As part of a study aimed at determining the kinematical and chemical proper- ties of Terzan 5, we present the first characterization of the bulge stars surround- ing this puzzling Stellar System. We observed 615 targets located well beyond the tidal radius of Terzan 5 and we found that their radial velocity distribution is well described by a Gaussian function peaked at = +21.0±4.6 kms −1 and with dispersionv = 113.0 ± 2.7 kms −1 . This is the one of the few high- precision spectroscopic survey of radial velocities for a large sample of bulge stars in such a low and positive latitude environment (b=+1.7°). We found no evi- dence for the peak at ∼ +200 kms −1 found in Nidever et al. (2012). The strong contamination of many observed spectra by TiO bands prevented us from deriving the iron abundance for the entire spectroscopic sample, introducing a selection bias. The metallicity distribution was finally derived for a sub-sample of 112 stars in a magnitude range where the effect of the selection bias is neg- ligible. The distribution is quite broad and roughly peaked at solar metallicity ((Fe/H)≃ +0.05 dex) with a similar number of stars in the super-solar and in the sub-solar ranges. The population number ratios in different metallicity ranges agree well with those observed in other low-latitude bulge fields suggesting (i) the possible presence of a plateau for |b| < 4° for the ratio between stars in the
B Lanzoni - One of the best experts on this subject based on the ideXlab platform.
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the age of the young bulge like population in the Stellar System terzan 5 linking the galactic bulge to the high z universe
The Astrophysical Journal, 2016Co-Authors: F R Ferraro, B Lanzoni, E Dalessandro, R M Rich, L Origlia, D Massari, A MucciarelliAbstract:The Galactic bulge is dominated by an old, metal-rich Stellar population. The possible presence and the amount of a young (a few gigayears old) minor component is one of the major issues debated in the literature. Recently, the bulge Stellar System Terzan 5 was found to harbor three sub-populations with iron content varying by more than one order of magnitude (from 0.2 up to two times the solar value), with chemical abundance patterns strikingly similar to those observed in bulge field stars. Here we report on the detection of two distinct main-sequence turnoff points in Terzan 5, providing the age of the two main Stellar populations: 12 Gyr for the (dominant) sub-solar component and 4.5 Gyr for the component at super-solar metallicity. This discovery classifies Terzan 5 as a site in the Galactic bulge where multiple bursts of star formation occurred, thus suggesting a quite massive progenitor possibly resembling the giant clumps observed in star-forming galaxies at high redshifts. This connection opens a new route of investigation into the formation process and evolution of spheroids and their Stellar content. Based on data obtained with (1) the ESA/NASA HST, under programs GO-14061, GO-12933, GO-10845, (2) the Very Large Telescope of the European Southern Observatory during the Science Verification of the camera MAD; (3) the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA.
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the binary mass transfer origin of the red blue straggler sequence in m30
The Astrophysical Journal, 2015Co-Authors: F R Ferraro, B Lanzoni, E Dalessandro, P Lu, Licai Deng, G BeccariAbstract:Two separated sequences of blue straggler stars (BSSs) have been revealed by Ferraro et?al. in the color-magnitude diagram (CMD) of the Milky Way globular cluster M30. Their presence has been suggested to be related to the two BSS formation channels (namely, collisions and mass transfer in close binaries) operating within the same Stellar System. The blue sequence was indeed found to be well reproduced by collisional BSS models. In contrast, no specific models for mass-transfer BSSs were available for an old Stellar System like M30. Here we present binary evolution models, including case-B mass transfer and binary merging, specifically calculated for this cluster. We discuss in detail the evolutionary track of a 0.9 + 0.5 M ? binary, which spends approximately 4?Gyr in the BSS region of the CMD of a 13?Gyr old cluster. We also run Monte Carlo simulations to study the distribution of mass-transfer BSSs in the CMD and to compare it with the observational data. Our results show that (1) the color and magnitude distribution of synthetic mass-transfer BSSs defines a strip in the CMD that nicely matches the observed red-BSS sequence, thus providing strong support to the mass-transfer origin for these stars; (2) the CMD distribution of synthetic BSSs never attains the observed location of the blue-BSS sequence, thus reinforcing the hypothesis that the latter formed through a different channel (likely collisions); (3) most (~60%) of the synthetic BSSs are produced by mass-transfer models, while the remaining <40% requires the contribution from merger models.
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ceci n est pas a globular cluster the metallicity distribution of the Stellar System terzan 5
The Astrophysical Journal, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, E Valenti, Rodrigo A Ibata, L LovisiAbstract:We present new determinations of the iron abundance for 220 stars belonging to the Stellar System Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the Very Large Telescope of the European Southern Observatory and DEIMOS at the Keck II Telescope. This is by far the largest spectroscopic sample of stars ever observed in this Stellar System. From this data set, a subsample of targets with spectra unaffected by TiO bands was extracted and statistically decontaminated from field stars. Once combined with 34 additional stars previously published by our group, a total sample of 135 member stars covering the entire radial extent of the System has been used to determine the metallicity distribution function of Terzan 5. The iron distribution clearly shows three peaks: a super-solar component at [Fe/H] ≅ 0.25 dex, accounting for ∼29% of the sample, a dominant sub-solar population at [Fe/H] ≅ –0.30 dex, corresponding to ∼62% of the total, and a minor (6%) metal-poor component at [Fe/H] ≅ –0.8 dex. Such a broad, multi-modal metallicity distribution demonstrates that Terzan 5 is not a genuine globular cluster but the remnant of a much more complex Stellar System.
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ceci n est pas a globular cluster the metallicity distribution of the Stellar System terzan 5
arXiv: Solar and Stellar Astrophysics, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, E Valenti, Rodrigo A Ibata, L LovisiAbstract:We present new determinations of the iron abundance for 220 stars belonging to the Stellar System Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the Very Large Telescope of the European Southern Observatory and DEIMOS at the Keck II Telescope. This is by far the largest spectroscopic sample of stars ever observed in this Stellar System. From this dataset, a subsample of targets with spectra unaffected by TiO bands was extracted and statistically decontaminated from field stars. Once combined with 34 additional stars previously published by our group, a total sample of 135 member stars covering the entire radial extent of the System has been used to determine the metallicity distribution function of Terzan 5. The iron distribution clearly shows three peaks: a super-solar component at [Fe/H]$\simeq0.25$ dex, accounting for 29% of the sample, a dominant sub-solar population at [Fe/H]$\simeq-0.30$ dex, corresponding to 62% of the total, and a minor (6%) metal-poor component at [Fe/H]$\simeq-0.8$ dex. Such a broad, multi-modal metallicity distribution demonstrates that Terzan 5 is not a genuine globular cluster but the remnant of a much more complex Stellar System.
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chemical and kinematical properties of galactic bulge stars surrounding the Stellar System terzan 5
The Astrophysical Journal, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, Rodrigo A Ibata, L Lovisi, M BellazziniAbstract:As part of a study aimed at determining the kinematical and chemical proper- ties of Terzan 5, we present the first characterization of the bulge stars surround- ing this puzzling Stellar System. We observed 615 targets located well beyond the tidal radius of Terzan 5 and we found that their radial velocity distribution is well described by a Gaussian function peaked at = +21.0±4.6 kms −1 and with dispersionv = 113.0 ± 2.7 kms −1 . This is the one of the few high- precision spectroscopic survey of radial velocities for a large sample of bulge stars in such a low and positive latitude environment (b=+1.7°). We found no evi- dence for the peak at ∼ +200 kms −1 found in Nidever et al. (2012). The strong contamination of many observed spectra by TiO bands prevented us from deriving the iron abundance for the entire spectroscopic sample, introducing a selection bias. The metallicity distribution was finally derived for a sub-sample of 112 stars in a magnitude range where the effect of the selection bias is neg- ligible. The distribution is quite broad and roughly peaked at solar metallicity ((Fe/H)≃ +0.05 dex) with a similar number of stars in the super-solar and in the sub-solar ranges. The population number ratios in different metallicity ranges agree well with those observed in other low-latitude bulge fields suggesting (i) the possible presence of a plateau for |b| < 4° for the ratio between stars in the
A Mucciarelli - One of the best experts on this subject based on the ideXlab platform.
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first phase space portrait of a hierarchical Stellar structure in the milky way
arXiv: Astrophysics of Galaxies, 2021Co-Authors: E Dalessandro, A Mucciarelli, M Bellazzini, L Origlia, Anna Lisa Varri, Maria A Tiongco, Enrico Vesperini, C Fanelli, S Saracino, E OlivaAbstract:We present the first detailed observational picture of a possible ongoing massive cluster hierarchical assembly in the Galactic disk as revealed by the analysis of the Stellar full phase-space (3D positions and kinematics and spectro-photometric properties) of an extended area ($6^{\circ}$ diameter) surrounding the well-known $\it h$ and $\chi$ Persei double Stellar cluster in the Perseus Arm. Gaia-EDR3 shows that the area is populated by seven co-moving clusters, three of which were previously unknown, and by an extended and quite massive ($M\sim10^5 M_{\odot}$) halo. All stars and clusters define a complex structure with evidence of possible mutual interactions in the form of intra-cluster over-densities and/or bridges. They share the same chemical abundances (half-solar metallicity) and age ($t\sim20$ Myr) within a small confidence interval and the Stellar density distribution of the surrounding diffuse Stellar halo resembles that of a cluster-like Stellar System. The combination of these evidences suggests that stars distributed within a few degrees from $\it h$ and $\chi$ Persei are part of a common, sub-structured Stellar complex that we named LISCA I. Comparison with results obtained through direct $N$-body simulations suggest that LISCA I may be at an intermediate stage of an ongoing cluster assembly that can eventually evolve in a relatively massive (a few $10^5 M_{\odot}$) Stellar System. We argue that such cluster formation mechanism may be quite efficient in the Milky Way and disk-like galaxies and, as a consequence, it has a relevant impact on our understanding of cluster formation efficiency as a function of the environment and redshift.
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the age of the young bulge like population in the Stellar System terzan 5 linking the galactic bulge to the high z universe
The Astrophysical Journal, 2016Co-Authors: F R Ferraro, B Lanzoni, E Dalessandro, R M Rich, L Origlia, D Massari, A MucciarelliAbstract:The Galactic bulge is dominated by an old, metal-rich Stellar population. The possible presence and the amount of a young (a few gigayears old) minor component is one of the major issues debated in the literature. Recently, the bulge Stellar System Terzan 5 was found to harbor three sub-populations with iron content varying by more than one order of magnitude (from 0.2 up to two times the solar value), with chemical abundance patterns strikingly similar to those observed in bulge field stars. Here we report on the detection of two distinct main-sequence turnoff points in Terzan 5, providing the age of the two main Stellar populations: 12 Gyr for the (dominant) sub-solar component and 4.5 Gyr for the component at super-solar metallicity. This discovery classifies Terzan 5 as a site in the Galactic bulge where multiple bursts of star formation occurred, thus suggesting a quite massive progenitor possibly resembling the giant clumps observed in star-forming galaxies at high redshifts. This connection opens a new route of investigation into the formation process and evolution of spheroids and their Stellar content. Based on data obtained with (1) the ESA/NASA HST, under programs GO-14061, GO-12933, GO-10845, (2) the Very Large Telescope of the European Southern Observatory during the Science Verification of the camera MAD; (3) the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA.
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ceci n est pas a globular cluster the metallicity distribution of the Stellar System terzan 5
The Astrophysical Journal, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, E Valenti, Rodrigo A Ibata, L LovisiAbstract:We present new determinations of the iron abundance for 220 stars belonging to the Stellar System Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the Very Large Telescope of the European Southern Observatory and DEIMOS at the Keck II Telescope. This is by far the largest spectroscopic sample of stars ever observed in this Stellar System. From this data set, a subsample of targets with spectra unaffected by TiO bands was extracted and statistically decontaminated from field stars. Once combined with 34 additional stars previously published by our group, a total sample of 135 member stars covering the entire radial extent of the System has been used to determine the metallicity distribution function of Terzan 5. The iron distribution clearly shows three peaks: a super-solar component at [Fe/H] ≅ 0.25 dex, accounting for ∼29% of the sample, a dominant sub-solar population at [Fe/H] ≅ –0.30 dex, corresponding to ∼62% of the total, and a minor (6%) metal-poor component at [Fe/H] ≅ –0.8 dex. Such a broad, multi-modal metallicity distribution demonstrates that Terzan 5 is not a genuine globular cluster but the remnant of a much more complex Stellar System.
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ceci n est pas a globular cluster the metallicity distribution of the Stellar System terzan 5
arXiv: Solar and Stellar Astrophysics, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, E Valenti, Rodrigo A Ibata, L LovisiAbstract:We present new determinations of the iron abundance for 220 stars belonging to the Stellar System Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the Very Large Telescope of the European Southern Observatory and DEIMOS at the Keck II Telescope. This is by far the largest spectroscopic sample of stars ever observed in this Stellar System. From this dataset, a subsample of targets with spectra unaffected by TiO bands was extracted and statistically decontaminated from field stars. Once combined with 34 additional stars previously published by our group, a total sample of 135 member stars covering the entire radial extent of the System has been used to determine the metallicity distribution function of Terzan 5. The iron distribution clearly shows three peaks: a super-solar component at [Fe/H]$\simeq0.25$ dex, accounting for 29% of the sample, a dominant sub-solar population at [Fe/H]$\simeq-0.30$ dex, corresponding to 62% of the total, and a minor (6%) metal-poor component at [Fe/H]$\simeq-0.8$ dex. Such a broad, multi-modal metallicity distribution demonstrates that Terzan 5 is not a genuine globular cluster but the remnant of a much more complex Stellar System.
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chemical and kinematical properties of galactic bulge stars surrounding the Stellar System terzan 5
The Astrophysical Journal, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, Rodrigo A Ibata, L Lovisi, M BellazziniAbstract:As part of a study aimed at determining the kinematical and chemical proper- ties of Terzan 5, we present the first characterization of the bulge stars surround- ing this puzzling Stellar System. We observed 615 targets located well beyond the tidal radius of Terzan 5 and we found that their radial velocity distribution is well described by a Gaussian function peaked at = +21.0±4.6 kms −1 and with dispersionv = 113.0 ± 2.7 kms −1 . This is the one of the few high- precision spectroscopic survey of radial velocities for a large sample of bulge stars in such a low and positive latitude environment (b=+1.7°). We found no evi- dence for the peak at ∼ +200 kms −1 found in Nidever et al. (2012). The strong contamination of many observed spectra by TiO bands prevented us from deriving the iron abundance for the entire spectroscopic sample, introducing a selection bias. The metallicity distribution was finally derived for a sub-sample of 112 stars in a magnitude range where the effect of the selection bias is neg- ligible. The distribution is quite broad and roughly peaked at solar metallicity ((Fe/H)≃ +0.05 dex) with a similar number of stars in the super-solar and in the sub-solar ranges. The population number ratios in different metallicity ranges agree well with those observed in other low-latitude bulge fields suggesting (i) the possible presence of a plateau for |b| < 4° for the ratio between stars in the
L Origlia - One of the best experts on this subject based on the ideXlab platform.
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first phase space portrait of a hierarchical Stellar structure in the milky way
arXiv: Astrophysics of Galaxies, 2021Co-Authors: E Dalessandro, A Mucciarelli, M Bellazzini, L Origlia, Anna Lisa Varri, Maria A Tiongco, Enrico Vesperini, C Fanelli, S Saracino, E OlivaAbstract:We present the first detailed observational picture of a possible ongoing massive cluster hierarchical assembly in the Galactic disk as revealed by the analysis of the Stellar full phase-space (3D positions and kinematics and spectro-photometric properties) of an extended area ($6^{\circ}$ diameter) surrounding the well-known $\it h$ and $\chi$ Persei double Stellar cluster in the Perseus Arm. Gaia-EDR3 shows that the area is populated by seven co-moving clusters, three of which were previously unknown, and by an extended and quite massive ($M\sim10^5 M_{\odot}$) halo. All stars and clusters define a complex structure with evidence of possible mutual interactions in the form of intra-cluster over-densities and/or bridges. They share the same chemical abundances (half-solar metallicity) and age ($t\sim20$ Myr) within a small confidence interval and the Stellar density distribution of the surrounding diffuse Stellar halo resembles that of a cluster-like Stellar System. The combination of these evidences suggests that stars distributed within a few degrees from $\it h$ and $\chi$ Persei are part of a common, sub-structured Stellar complex that we named LISCA I. Comparison with results obtained through direct $N$-body simulations suggest that LISCA I may be at an intermediate stage of an ongoing cluster assembly that can eventually evolve in a relatively massive (a few $10^5 M_{\odot}$) Stellar System. We argue that such cluster formation mechanism may be quite efficient in the Milky Way and disk-like galaxies and, as a consequence, it has a relevant impact on our understanding of cluster formation efficiency as a function of the environment and redshift.
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the age of the young bulge like population in the Stellar System terzan 5 linking the galactic bulge to the high z universe
The Astrophysical Journal, 2016Co-Authors: F R Ferraro, B Lanzoni, E Dalessandro, R M Rich, L Origlia, D Massari, A MucciarelliAbstract:The Galactic bulge is dominated by an old, metal-rich Stellar population. The possible presence and the amount of a young (a few gigayears old) minor component is one of the major issues debated in the literature. Recently, the bulge Stellar System Terzan 5 was found to harbor three sub-populations with iron content varying by more than one order of magnitude (from 0.2 up to two times the solar value), with chemical abundance patterns strikingly similar to those observed in bulge field stars. Here we report on the detection of two distinct main-sequence turnoff points in Terzan 5, providing the age of the two main Stellar populations: 12 Gyr for the (dominant) sub-solar component and 4.5 Gyr for the component at super-solar metallicity. This discovery classifies Terzan 5 as a site in the Galactic bulge where multiple bursts of star formation occurred, thus suggesting a quite massive progenitor possibly resembling the giant clumps observed in star-forming galaxies at high redshifts. This connection opens a new route of investigation into the formation process and evolution of spheroids and their Stellar content. Based on data obtained with (1) the ESA/NASA HST, under programs GO-14061, GO-12933, GO-10845, (2) the Very Large Telescope of the European Southern Observatory during the Science Verification of the camera MAD; (3) the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA.
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ceci n est pas a globular cluster the metallicity distribution of the Stellar System terzan 5
The Astrophysical Journal, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, E Valenti, Rodrigo A Ibata, L LovisiAbstract:We present new determinations of the iron abundance for 220 stars belonging to the Stellar System Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the Very Large Telescope of the European Southern Observatory and DEIMOS at the Keck II Telescope. This is by far the largest spectroscopic sample of stars ever observed in this Stellar System. From this data set, a subsample of targets with spectra unaffected by TiO bands was extracted and statistically decontaminated from field stars. Once combined with 34 additional stars previously published by our group, a total sample of 135 member stars covering the entire radial extent of the System has been used to determine the metallicity distribution function of Terzan 5. The iron distribution clearly shows three peaks: a super-solar component at [Fe/H] ≅ 0.25 dex, accounting for ∼29% of the sample, a dominant sub-solar population at [Fe/H] ≅ –0.30 dex, corresponding to ∼62% of the total, and a minor (6%) metal-poor component at [Fe/H] ≅ –0.8 dex. Such a broad, multi-modal metallicity distribution demonstrates that Terzan 5 is not a genuine globular cluster but the remnant of a much more complex Stellar System.
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ceci n est pas a globular cluster the metallicity distribution of the Stellar System terzan 5
arXiv: Solar and Stellar Astrophysics, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, E Valenti, Rodrigo A Ibata, L LovisiAbstract:We present new determinations of the iron abundance for 220 stars belonging to the Stellar System Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the Very Large Telescope of the European Southern Observatory and DEIMOS at the Keck II Telescope. This is by far the largest spectroscopic sample of stars ever observed in this Stellar System. From this dataset, a subsample of targets with spectra unaffected by TiO bands was extracted and statistically decontaminated from field stars. Once combined with 34 additional stars previously published by our group, a total sample of 135 member stars covering the entire radial extent of the System has been used to determine the metallicity distribution function of Terzan 5. The iron distribution clearly shows three peaks: a super-solar component at [Fe/H]$\simeq0.25$ dex, accounting for 29% of the sample, a dominant sub-solar population at [Fe/H]$\simeq-0.30$ dex, corresponding to 62% of the total, and a minor (6%) metal-poor component at [Fe/H]$\simeq-0.8$ dex. Such a broad, multi-modal metallicity distribution demonstrates that Terzan 5 is not a genuine globular cluster but the remnant of a much more complex Stellar System.
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chemical and kinematical properties of galactic bulge stars surrounding the Stellar System terzan 5
The Astrophysical Journal, 2014Co-Authors: D Massari, B Lanzoni, F R Ferraro, E Dalessandro, A Mucciarelli, R M Rich, L Origlia, Rodrigo A Ibata, L Lovisi, M BellazziniAbstract:As part of a study aimed at determining the kinematical and chemical proper- ties of Terzan 5, we present the first characterization of the bulge stars surround- ing this puzzling Stellar System. We observed 615 targets located well beyond the tidal radius of Terzan 5 and we found that their radial velocity distribution is well described by a Gaussian function peaked at = +21.0±4.6 kms −1 and with dispersionv = 113.0 ± 2.7 kms −1 . This is the one of the few high- precision spectroscopic survey of radial velocities for a large sample of bulge stars in such a low and positive latitude environment (b=+1.7°). We found no evi- dence for the peak at ∼ +200 kms −1 found in Nidever et al. (2012). The strong contamination of many observed spectra by TiO bands prevented us from deriving the iron abundance for the entire spectroscopic sample, introducing a selection bias. The metallicity distribution was finally derived for a sub-sample of 112 stars in a magnitude range where the effect of the selection bias is neg- ligible. The distribution is quite broad and roughly peaked at solar metallicity ((Fe/H)≃ +0.05 dex) with a similar number of stars in the super-solar and in the sub-solar ranges. The population number ratios in different metallicity ranges agree well with those observed in other low-latitude bulge fields suggesting (i) the possible presence of a plateau for |b| < 4° for the ratio between stars in the