scholarly journals Galactic or extragalactic chemical tagging for NGC 3201?

2018 ◽  
Vol 614 ◽  
pp. A146 ◽  
Author(s):  
B. Dias ◽  
I. Araya ◽  
J. P. Nogueira-Cavalcante ◽  
L. Saker ◽  
A. Shokry
Keyword(s):  
High Resolution ◽  
Globular Cluster ◽  
High Resolution Spectroscopy ◽  
Low Resolution ◽  
Element Abundances ◽  
Giant Stars ◽  
Mass Size ◽  
Red Giant ◽  
Process Element ◽  
Size Relation

Context. The origin of the globular cluster (GC) NGC 3201 is under debate. Its retrograde orbit points to an extragalactic origin, but no further chemical evidence supports this idea. Light-element chemical abundances are useful to tag GCs and can be used to shed light on this discussion. Aims. Recently it was shown that the CN and CH indices are useful to identify GCs that are anomalous to those typically found in the Milky Way. A possible origin of anomalous clusters is the merger of two GCs and/or the nucleus of a dwarf galaxy. We aim to derive CN and CH band strengths for red giant stars in NGC3201 and compare these with photometric indices and high-resolution spectroscopy and discuss in the context of GC chemical tagging. Methods. We measure molecular band indices of S(3839) and G4300 for CN and CH, respectively from low-resolution spectra of red giant stars. Gravity and temperature effects are removed. Photometric indices are used to indicate further chemical information on C+N+O or s-process element abundances that are not derived from low-resolution spectra. Results. We found three groups in the CN–CH distribution. A main sequence (S1), a secondary less-populated sequence (S2), and a group of peculiar (pec) CN-weak and CH-weak stars, one of which was previously known. The three groups seem to have different C+N+O and/or s-process element abundances, to be confirmed by high-resolution spectroscopy. These are typical characteristics of anomalous GCs. The CN distribution of NGC 3201 is quadrimodal, which is more common in anomalous clusters. However, NGC 3201 does not belong to the trend of anomalous GCs in the mass-size relation. Conclusions. The globular cluster NGC 3201 shows signs that it can be chemically tagged as anomalous: it has an unusual CN–CH relation, indications that pec-S1-S2 is an increasing sequence of C+N+O or s-process element abundances, and a multi-modal CN distribution that seems to correlate with s-process element abundances. The non-anomalous characteristics are that it has a debatable Fe-spread and it does not follow the trend of mass size of all anomalous clusters. Three scenarios are postulated here: (i) if the sequence pec-S1-S2 has increasing C+N+O and s-process element abundances, NGC 3201 would be the first anomalous GC outside of the mass-size relation; (ii) if the abundances are almost constant, NGC 3201 would be the first non-anomalous GC with multiple CN–CH anti-correlation groups; or (iii) it would be the first anomalous GC without variations in C+N+O and s-process element abundances. In all cases, the definition of anomalous clusters and the scenario in which they have an extragalactic origin must be revised.

scholarly journals Stellar spectra analysis of giant stars: ARCTURUS

2020 ◽  
pp. 347-348
Author(s):  
Maria Rah
Keyword(s):  
High Resolution ◽  
Early Universe ◽  
Chemical Evolution ◽  
The Other ◽  
High Resolution Spectroscopy ◽  
Spectra Analysis ◽  
Stellar Spectra ◽  
Giant Stars ◽  
Low Metallicity ◽  
Red Giant

In this study, we analyzed the evolved red giant ARCTURUS using high-resolution spectroscopy that was taken by HARPS. The other names of this star is α Boo - Arcturus - HR 5340 - HD 124897 - HIP 69673. This evolved (log g = 1.66 dex) star shows low metallicity nature ([Fe/H] = -0.52), which could be employed to study the chemical evolution of the early universe.

scholarly journals Globular cluster contributions to Galactic halo assembly

2012 ◽  
Vol 10 (H16) ◽  
pp. 286-287
Author(s):  
Sarah L. Martell
Keyword(s):  
Star Formation ◽  
Globular Cluster ◽  
Second Generation ◽  
Galactic Halo ◽  
Cluster Formation ◽  
Light Element ◽  
Element Abundances ◽  
Giant Stars ◽  
Red Giant

AbstractI discuss a search for red giant stars in the Galactic halo with light-element abundances similar to second-generation globular cluster stars, and discuss the implications of such a population for globular cluster formation models and the balance between in situ star formation and accretion for the assembly of the Galactic halo.

scholarly journals Joint Discussion 4 UV astronomy: stars from birth to death

2006 ◽  
Vol 2 (14) ◽  
pp. 169-194
Author(s):  
Ana I. Gómez de Castro ◽  
Martin A. Barstow
Keyword(s):  
High Resolution ◽  
Uv Spectroscopy ◽  
Broad Band ◽  
Mission Planning ◽  
High Resolution Spectroscopy ◽  
Low Resolution ◽  
Short Term ◽  
Uv Astronomy ◽  
Optical Telescope ◽  
The Moment

AbstractThe scientific program is presented as well a the abstracts of the contributions. An extended account is published in “The Ultraviolet Universe: stars from birth to death” (Ed. Gómez de Castro) published by the Editorial Complutense de Madrid (UCM), that can be accessed by electronic format through the website of the Network for UV Astronomy (www.ucm.es/info/nuva).There are five telescopes currently in orbit that have a UV capability of some description. At the moment, only FUSE provides any medium- to high-resolution spectroscopic capability. GALEX, the XMM UV-Optical Telescope (UVOT) and the Swift. UVOT mainly delivers broad-band imaging, but with some low-resolution spectroscopy using grisms. The primary UV spectroscopic capability of HST was lost when the Space Telescope Imaging Spectrograph failed in 2004, but UV imaging is still available with the HST-WFPC2 and HST-ACS instruments.With the expected limited lifetime of sl FUSE, UV spectroscopy will be effectively unavailable in the short-term future. Even if a servicing mission of HST does go ahead, to install COS and repair STIS, the availability of high-resolution spectroscopy well into the next decade will not have been addressed. Therefore, it is important to develop new missions to complement and follow on from the legacy of FUSE and HST, as well as the smaller imaging/low resolution spectroscopy facilities. This contribution presents an outline of the UV projects, some of which are already approved for flight, while others are still at the proposal/study stage of their development.This contribution outlines the main results from Joint Discussion 04 held during the IAU General Assembly in Prague, August 2006, concerning the rationale behind the needs of the astronomical community, in particular the stellar astrophysics community, for new UV instrumentation. Recent results from UV observations were presented and future science goals were laid out. These goals will lay the framework for future mission planning.

scholarly journals On the synergy between Ariel and ground-based high-resolution spectroscopy

2022 ◽  
Author(s):  
Gloria Guilluy ◽  
Alessandro Sozzetti ◽  
Paolo Giacobbe ◽  
Aldo S. Bonomo ◽  
Giuseppina Micela
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Major Axis ◽  
High Resolution Spectroscopy ◽  
Correlation Technique ◽  
Temperature Structure ◽  
Low Resolution ◽  
Semi Major Axis ◽  
Species Discovery ◽  
Orbital Parameters

AbstractSince the first discovery of an extra-solar planet around a main-sequence star, in 1995, the number of detected exoplanets has increased enormously. Over the past two decades, observational instruments (both onboard and on ground-based facilities) have revealed an astonishing diversity in planetary physical features (i. e. mass and radius), and orbital parameters (e.g. period, semi-major axis, inclination). Exoplanetary atmospheres provide direct clues to understand the origin of these differences through their observable spectral imprints. In the near future, upcoming ground and space-based telescopes will shift the focus of exoplanetary science from an era of “species discovery” to one of “atmospheric characterization”. In this context, the Atmospheric Remote-sensing Infrared Exoplanet Large (Ariel) survey, will play a key role. As it is designed to observe and characterize a large and diverse sample of exoplanets, Ariel will provide constraints on a wide gamut of atmospheric properties allowing us to extract much more information than has been possible so far (e.g. insights into the planetary formation and evolution processes). The low resolution spectra obtained with Ariel will probe layers different from those observed by ground-based high resolution spectroscopy, therefore the synergy between these two techniques offers a unique opportunity to understanding the physics of planetary atmospheres. In this paper, we set the basis for building up a framework to effectively utilise, at near-infrared wavelengths, high-resolution datasets (analyzed via the cross-correlation technique) with spectral retrieval analyses based on Ariel low-resolution spectroscopy. We show preliminary results, using a benchmark object, namely HD 209458 b, addressing the possibility of providing improved constraints on the temperature structure and molecular/atomic abundances.

scholarly journals Chemical analysis of NGC 6528: one of the most metal-rich bulge globular clusters

2018 ◽  
Vol 620 ◽  
pp. A96 ◽  
Author(s):  
C. Muñoz ◽  
D. Geisler ◽  
S. Villanova ◽  
I. Saviane ◽  
C. C. Cortés ◽  
...  
Keyword(s):  
High Resolution ◽  
Chemical Analysis ◽  
Iron Content ◽  
Globular Clusters ◽  
Chemical Characterization ◽  
Heavy Elements ◽  
High Resolution Spectroscopy ◽  
Origin And Evolution ◽  
Red Giant ◽  
Good Agreement

Context. The bulge globular clusters (GCs) are key tracers of the bulge, a central and ancient component of our Galaxy. It is essential to understand their formation and evolution to study that of the bulge, as well as their relationship with the other Galactic GC systems (halo and disk GCs). High-resolution spectroscopy is a powerful tool for such studies, allowing us to obtain a detailed chemical characterization and kinematics of the clusters and to compare their chemical patterns with those of their halo and disk counterparts. Aims. Our main goals are to obtain detailed abundances for a sample of seven red giant members of NGC 6528 in order to characterize their chemical composition and study the relationship of this GC with the bulge, and with other bulge, halo, and disk GCs. Moreover, we analyze this cluster’s behavior associated with the multiple-populations phenomenon. Methods. We obtained the stellar parameters and chemical abundances of light elements (Na, Al), iron-peak elements (V, Cr, Mn, Fe, Co, Ni, Cu), α-elements (O, Mg, Si, Ca, Ti) and heavy elements (Zr, Ba, Eu) in seven red giant members of NGC 6528 using high-resolution spectroscopy from FLAMES-UVES. Results. In six stars of our sample we obtained a mean iron content of [Fe/H] = − 0.14 ± 0.03 dex, in good agreement with other studies. We found no significant internal iron spread. We detected one candidate variable star, which was excluded from the mean in iron content, and derived a metallicity in this star of [Fe/H] = − 0.55 ± 0.04 dex. Moreover, we found no extended O-Na anticorrelation but instead only an intrinsic Na spread. In addition, NGC 6528 does not exhibit a Mg-Al anticorrelation, and no significant spread in either Mg or Al. The α and iron-peak elements show good agreement with the bulge field star trend. The heavy elements are slightly dominated by the r-process. The chemical analysis suggests an origin and evolution similar to that of typical old Galactic bulge field stars. Finally, we find remarkable agreement in the chemical patterns of NGC 6528 and another bulge GC, NGC 6553, suggesting a similar origin and evolution.

scholarly journals H-band discovery of additional second-generation stars in the Galactic bulge globular cluster NGC 6522 as observed by APOGEE and Gaia

2019 ◽  
Vol 627 ◽  
pp. A178 ◽  
Author(s):  
J. G. Fernández-Trincado ◽  
O. Zamora ◽  
Diogo Souto ◽  
R. E. Cohen ◽  
F. Dell’Agli ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Second Generation ◽  
Elemental Abundance ◽  
Agb Stars ◽  
Giant Stars ◽  
Abundance Patterns ◽  
Evolution Experiment ◽  
Band Spectra ◽  
Stellar Sources ◽  
Process Element

We present an elemental abundance analysis of high-resolution spectra for five giant stars spatially located within the innermost regions of the bulge globular cluster NGC 6522 and derive Fe, Mg, Al, C, N, O, Si, and Ce abundances based on H-band spectra taken with the multi-object APOGEE-north spectrograph from the SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. Of the five cluster candidates, two previously unremarked stars are confirmed to have second-generation (SG) abundance patterns, with the basic pattern of depletion in C and Mg simultaneous with enrichment in N and Al as seen in other SG globular cluster populations at similar metallicity. In agreement with the most recent optical studies, the NGC 6522 stars analyzed exhibit (when available) only mild overabundances of the s-process element Ce, contradicting the idea that NGC 6522 stars are formed from gas enriched by spinstars and indicating that other stellar sources such as massive AGB stars could be the primary polluters of intra-cluster medium. The peculiar abundance signatures of SG stars have been observed in our data, confirming the presence of multiple generations of stars in NGC 6522.

scholarly journals Solar-like oscillations in subgiant and red-giant stars: mixed modes

2013 ◽  
Vol 9 (S301) ◽  
pp. 325-331 ◽  
Author(s):  
S. Hekker ◽  
A. Mazumdar
Keyword(s):  
High Resolution ◽  
Outer Part ◽  
Space Missions ◽  
Giant Stars ◽  
Internal Structures ◽  
Different Depths ◽  
Mixed Modes ◽  
Red Giant Stars ◽  
Red Giant

AbstractThanks to significant improvements in high-resolution spectrographs and the launch of dedicated space missions MOST, CoRoT and Kepler, the number of subgiants and red-giant stars with detected oscillations has increased significantly over the last decade. The amount of detail that can now be resolved in the oscillation patterns does allow for in-depth investigations of the internal structures of these stars. One phenomenon that plays an important role in such studies are mixed modes. These are modes that carry information of the inner radiative region as well as from the convective outer part of the star allowing to probe different depths of the stars.Here, we describe mixed modes and highlight some recent results obtained using mixed modes observed in subgiants and red-giant stars.

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