Stellar parameters for Pop II A-type stars from IUE spectra and new-ODF ATLAS9 model atmospheres

Castelli, F.; Cacciari, C.

doi:10.1051/0004-6361:20011445

Cited by 13 publications

(10 citation statements)

References 17 publications

(38 reference statements)

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“…Stellar parameters (log g, [Fe/H] and [α/Fe]) were determined using a minimum χ 2 program written for this dataset. The program compares each observed spectrum to a large grid of synthetic spectra, generated using the LTE stellar synthesis program MOOG 2010 (Sneden 1973, and subsequent updates) from the Castelli & Cacciari (2001) 1D model atmospheres with no convective overshooting (Castelli & Kurucz 2004). An assumption of a constant microturbulent velocity may be a source of error in our analysis.…”

Section: Overview: Measuring Stellar Parametersmentioning

confidence: 99%

ARGOS – II. The Galactic bulge survey

Freeman¹,

Ness²,

Wylie-de-Boer³

et al. 2012

Monthly Notices of the Royal Astronomical Society

144

164

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We describe the motivation, field locations and stellar selection for the ARGOS spectroscopic survey of 28,000 stars in the bulge and inner disk of the Milky Way galaxy across latitudes of b = −5 • to −10 • . The primary goal of this survey is to constrain the formation processes of the bulge and establish whether it is predominantly a merger or instability remnant. From the spectra (R = 11,000), we have measured radial velocities and determined stellar parameters, including metallicities and [α/Fe] ratios. Distances were estimated from the derived stellar parameters and about 14,000 stars are red giants within 3.5 kpc of the Galactic centre. In this paper, we present the observations and analysis methods. Subsequent papers (III and IV) will discuss the stellar metallicity distribution and kinematics of the Galactic bulge and inner disk, and the implications for the formation of the bulge.

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Section: Overview: Measuring Stellar Parametersmentioning

confidence: 99%

ARGOS – II. The Galactic bulge survey

Freeman¹,

Ness²,

Wylie-de-Boer³

et al. 2012

Monthly Notices of the Royal Astronomical Society

144

164

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“…4). These populations were created using IAC-STAR (Aparicio & Gallart 2004) using Teramo stellar evolution libraries (Pietrinferni et al 2004); bolometric corrections libraries (Castelli & Cacciari 2001) and we assumed a Salpeter Initial Mass function. The stellar populations in Fig.…”

Section: The Stellar Populationmentioning

confidence: 99%

An E-ELT case study: colour–magnitude diagrams of an old galaxy in the Virgo cluster

Deep

Fiorentino

Tolstoy

et al. 2011

A&A

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One of the key science goals for a diffraction limited imager on an Extremely Large Telescope (ELT) is the resolution of individual stars down to faint limits in distant galaxies. The aim of this study is to test the proposed capabilities of a multi-conjugate adaptive optics (MCAO) assisted imager working at the diffraction limit, in IJHK s filters, on a 42m diameter ELT to carry out accurate stellar photometry in crowded images in an Elliptical-like galaxy at the distance of the Virgo cluster. As the basis for realistic simulations we have used the phase A studies of the European-ELT project, including the MICADO imager (Davies & Genzel 2010) and the MAORY MCAO module (Diolaiti 2010). We convolved a complex resolved stellar population with the telescope and instrument performance expectations to create realistic images. We then tested the ability of the currently available photometric packages STARFINDER and DAOPHOT to handle the simulated images. Our results show that deep Colour-Magnitude Diagrams (photometric error, ±0.25 at I≥27.2; H≥25. and K s ≥24.6) of old stellar populations in galaxies, at the distance of Virgo, are feasible at a maximum surface brightness, µ V ∼ 17 mag/arcsec 2 (down to M I > −4 and M H ∼ M K > −6), and significantly deeper (photometric error, ±0.25 at I≥29.3; H≥26.6 and K s ≥26.2) for µ V ∼ 21 mag/arcsec 2 (down to M I ≥ −2 and M H ∼ M K ≥ −4.5). The photometric errors, and thus also the depth of the photometry should be improved with photometry packages specifically designed to adapt to an ELT MCAO Point Spread Function. We also make a simple comparison between these simulations and what can be expected from a Single Conjugate Adaptive Optics feed to MICADO and also the James Webb Space Telescope.

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“…The work by Castelli & Cacciari (2001) suggests that this worry is well founded. They carried out an extensive FUV analysis of Pop II A-stars, based on the same set of Kurucz models that we employ here.…”

Section: Star 999: a Bright And Probably Massive Bluementioning

confidence: 99%

Stellar Exotica in 47 Tucanae

Knigge

Dieball

Apellániz

et al. 2008

Astrophysical Journal

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We present far-UV spectroscopy obtained with HST for 48 blue objects in the core of 47 Tuc. Based on their position in a FUV-optical colour-magnitude diagram, these were expected to include cataclysmic variables (CVs), blue stragglers (BSs), white dwarfs (WDs) and other exotic objects. For a subset of these sources, we also construct FUV-NIR SEDs. Based on our analysis of this extensive data set, we report the following main results. (1) We spectroscopically confirm 3 previously known or suspected CVs via the detection of emission lines and find new evidence for dwarf nova eruptions in two of these. (2) Only one other source in our spectroscopic sample exhibits marginal evidence for line emission, but predicted and observed CV numbers still agree to within a factor of about 2-3. (3) We have discovered a hot (T_eff = 8700 K), low-mass (M = 0.05 M_sun) secondary star in a previously known 0.8 day binary system. This exotic object is probably the remnant of a subgiant that has been stripped of its envelope and may represent the ``smoking gun'' of a recent dynamical encounter. (4) We have found a Helium WD, the second to be optically detected in 47 Tuc, and the first outside a millisecond-pulsar system. (5) We have discovered a BS-WD binary system, the first known in any globular cluster. (6) We have found two additional candidate WD binary systems with putative main sequence and subgiant companions. (7) We estimate the WD binary fraction in the core of 47 Tuc to be 15 +17/-9 (stat) +8/-7 (sys). (8) One BS in our sample may exceed twice the cluster turn-off mass, but the uncertainties are large. Taken as a whole, our study illustrates the wide range of stellar exotica that are lurking in the cores of GCs, most of which are likely to have undergone significant dynamical encounters. [abridged]Comment: 28 pages, 22 figures, 1 table, accepted for publication in ApJ; abstract below is abridged; new version corrects some typos and updates some references; a copy with some higher resolution figures is available from http://www.astro.soton.ac.uk/~christian (under "Research"

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Stellar parameters for Pop II A-type stars from IUE spectra and new-ODF ATLAS9 model atmospheres

Cited by 13 publications

References 17 publications

ARGOS – II. The Galactic bulge survey

ARGOS – II. The Galactic bulge survey

An E-ELT case study: colour–magnitude diagrams of an old galaxy in the Virgo cluster

Stellar Exotica in 47 Tucanae

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