Measurements of rotation and turbulence in F, G, and K dwarfs

Gray, David F.

doi:10.1086/162149

Cited by 123 publications

(106 citation statements)

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“…The 0.55 scale factor implies that the granulation velocities in αSer are slightly more than half as large as the solar values. Although this is consistent with the general drop in macroturbulence with declining effective temperature (Gray 1984(Gray , 1988Gray & Nagar 1985;Gray & Toner 1986), a value of 0.55 is one of the lowest yet measured (Gray & Pugh 2012, Papers 1 and 2). It is small compared to 0.80 for βGem and 1.10 for εCyg, but is not inconsistent with the run of values in Figure 7 of Gray & Pugh (2012).…”

Section: The Third Signature Of Granulation-convective Blueshiftssupporting

confidence: 81%

“…Early Fourier analyses were uncertain for a number of reasons with values of 2.3±1.0 km s −1 (Gray & Martin 1979), 2.0±0.3 (Smith & Dominy 1979), and no detectable rotation (Gray 1982, Gray & Pallavicini 1989. Other values include an upper limit of ∼1.6 km s −1 by de Medeiros & Mayor (1999), who used the template-correlation spectrograph CORAVEL with an empirical correction for macroturbulence broadening (Benz & Mayor 1981, 1984. Apparently this value was revised to 1.9 km s −1 by Pasquini et al (2000).…”

Section: Introductionmentioning

confidence: 99%

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Rotation and Granulation of the K2 Giant Α Ser

Gray

2016

ApJ

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The red giant α Ser was observed over 10 seasons, 2001-2010, at the Elginfield Observatory with the highresolution coudé spectrograph. Season-mean radial velocities appear to show a small secular rise ∼11±3 m s −1 yr −1 . The absolute spectroscopic radial velocity with convective blueshifts taken into account is 2730 m s −1 . Ten line-depth ratios were investigated and show that the starʼs temperature is constant with any secular variation below 1.3±1.0 K over the 11 years of observation. Fourier analysis of the line broadening yields vsini = 2.0±0.3 km s −1 and a radial-tangential macroturbulence dispersion ζ RT =4.50±0.10 km s −1 . The third-granulation-signature plot shows that the granulation velocities of αSer are only 0.55±0.10 as large as the Sunʼs. The line bisector of Fe I λ6253 has the usual "C" shape and when mapped onto the third-signature plot results in a flux deficit that is slightly broader than seen in other measured K giants. The deficit fractional area of 12.3±1.5% suggests a temperature difference between granules and lanes of 105 K as seen averaged over the stellar disk.

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Section: The Third Signature Of Granulation-convective Blueshiftssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Rotation and Granulation of the K2 Giant Α Ser

Gray

2016

ApJ

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“…For both stars, only an upper limit on v sin i of about 3 km s −1 could be established. The Fourier analysis of the spectral lines combined with the availability of dedicated libraries of synthetic spectra may allow one to separate the contribution of rotation and macroturbulence (e.g., Gray 1984). Here, exploratory calculations of the mean profile Fourier transform suggest, based on the relative height and shape of the sidelobes (in particular the squeezing of the first one; Gray 2005), that macroturbulence is the dominant broadening mechanism.…”

Section: Methods Of Analysismentioning

confidence: 99%

Abundance study of the two solar-analogue CoRoT targets HD 42618 and HD 43587 from HARPS spectroscopy

Morel

Rainer

Poretti

et al. 2013

A&A

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We present a detailed abundance study based on spectroscopic data obtained with HARPS of two solar-analogue main targets for the asteroseismology programme of the CoRoT satellite: HD 42618 and HD 43587. The atmospheric parameters and chemical composition are accurately determined through a fully differential analysis with respect to the Sun observed with the same instrumental set-up. Several sources of systematic errors largely cancel out with this approach, which allows us to narrow down the 1-σ error bars to typically 20 K in effective temperature, 0.04 dex in surface gravity, and less than 0.05 dex in the elemental abundances. Although HD 42618 fulfils many requirements for being classified as a solar twin, its slight deficiency in metals and its possibly younger age indicate that, strictly speaking, it does not belong to this class of objects. On the other hand, HD 43587 is slightly more massive and evolved. In addition, marked differences are found in the amount of lithium present in the photospheres of these two stars, which might reveal different mixing properties in their interiors. These results will put tight constraints on the forthcoming theoretical modelling of their solar-like oscillations and contribute to increase our knowledge of the fundamental parameters and internal structure of stars similar to our Sun.

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“…This difference may be of the order of 1−3 km s −1 for giants and supergiants (Gray 1981;Gray & Toner 1987) and somewhat larger for main sequence stars (Gray 1984). Since giants and supergiants are likely to dominate the line widths in both clusters, the importance of macroturbulence will be small, and will not be considered further.…”

Section: Cross-correlation Analysis: Radial Velocities and Line-of-simentioning

confidence: 99%

Dynamical masses of two young globular clusters in the blue compact galaxy ESO 338–IG04

Östlin

Cumming

Bergvall³

2006

A&A

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We present high-resolution échelle spectroscopy, obtained with the UVES spectrograph on ESO/VLT, of two luminous star clusters in the metal-poor blue compact galaxy ESO 338-IG04 at a distance of 37.5 Mpc. Cross-correlating with template stars, we obtain line-of-sight velocity dispersions of 33 and 17 km s −1 . By combining with size estimates from Hubble Space Telescope images we infer dynamical masses of 1.3 × 10 7 M and 4.0 × 10 6 M for the two clusters, making them among the most massive known. The less massive cluster is the faintest cluster for which a dynamical mass has yet been obtained. In both clusters we detect Balmer absorption lines which we use to estimate their ages. From the younger (∼6 Myr) and more massive cluster, we detect He ii λ4686 emission of intermediate width, indicating the presence of very massive O-stars. Moreover, analysis of the [O iii] λ5007 and Hα emission lines from the region near the younger cluster indicates that it is associated with a bubble expanding at ∼40 km s −1 . We also see from the Na i D absorption lines indications of neutral gas flows towards the younger cluster. We compare the dynamical masses with those derived from photometry and discuss implications for the stellar initial mass function (IMF) in each cluster. Both clusters are compatible with rather normal IMFs which will favour their long-term survival and evolution into massive bona fide globular clusters.

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Measurements of rotation and turbulence in F, G, and K dwarfs

Cited by 123 publications

References 0 publications

Rotation and Granulation of the K2 Giant Α Ser

Rotation and Granulation of the K2 Giant Α Ser

Abundance study of the two solar-analogue CoRoT targets HD 42618 and HD 43587 from HARPS spectroscopy

Dynamical masses of two young globular clusters in the blue compact galaxy ESO 338–IG04

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