- ID:
- ivo://CDS.VizieR/J/AJ/152/19
- Title:
- Pan-Pacific Planet Search (PPPS). V. 164 stars
- Short Name:
- J/AJ/152/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopic stellar parameters for the complete target list of 164 evolved stars from the Pan-Pacific Planet Search, a five-year radial velocity campaign using the 3.9m Anglo-Australian Telescope. For 87 of these bright giants, our work represents the first determination of their fundamental parameters. Our results carry typical uncertainties of 100K, 0.15dex, and 0.1dex in T_eff_, logg, and [Fe/H] and are consistent with literature values where available. The derived stellar masses have a mean of 1.31_-0.25_^+0.28^M_{Sun}_, with a tail extending to ~2M_{Sun}_, consistent with the interpretation of these targets as "retired" A-F type stars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/133/2464
- Title:
- Parameters and abundances of nearby giants
- Short Name:
- J/AJ/133/2464
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present parameter and abundance data for a sample of 298 nearby giants. The spectroscopic data for this work have a resolution of R~60000S/N>150, and spectral coverage from 475 to 685nm. Overall trends in the Z>10 abundances are dominated by Galactic chemical evolution, while the light-element abundances are influenced by stellar evolution, as well as Galactic evolution. We find several super-Li stars in our sample and confirm that Li abundances in the first giant branch are related to mixing depths.
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/2006
- Title:
- Phoenix dwarf galaxy RV and [Fe/H] catalog
- Short Name:
- J/MNRAS/466/2006
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Transition type dwarf galaxies are thought to be systems undergoing the process of transformation from a star-forming into a passively evolving dwarf, which makes them particularly suitable to study evolutionary processes driving the existence of different dwarf morphological types. Here we present results from a spectroscopic survey of ~200 individual red giant branch stars in the Phoenix dwarf, the closest transition type with a comparable luminosity to 'classical' dwarf galaxies. We measure a systemic heliocentric velocity Vhelio=-21.2+/-1.0km/s. Our survey reveals the clear presence of prolate rotation that is aligned with the peculiar spatial distribution of the youngest stars in Phoenix. We speculate that both features might have arisen from the same event, possibly an accretion of a smaller system. The evolved stellar population of Phoenix is relatively metal-poor (<[Fe/H]>=-1.49+/-0.04dex) and shows a large metallicity spread (sigma_[Fe/H]_=0.51+/-0.04dex), with a pronounced metallicity gradient of -0.13+/-0.01dex/arcmin similar to luminous, passive dwarf galaxies. We also report a discovery of an extremely metal-poor star candidate in Phoenix and discuss the importance of correcting for spatial sampling when interpreting the chemical properties of galaxies with metallicity gradients. This study presents a major leap forward in our knowledge of the internal kinematics of the Phoenix transition type dwarf galaxy and the first wide area spectroscopic survey of its metallicity properties.
- ID:
- ivo://CDS.VizieR/J/MNRAS/495/3087
- Title:
- Photometric sample of 2.6million red clump stars
- Short Name:
- J/MNRAS/495/3087
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Large pristine samples of red clump stars are highly sought after given that they are standard candles and give precise distances even at large distances. However, it is difficult to cleanly select red clumps stars because they can have the same Teff and logg as red giant branch stars. Recently, it was shown that the asteroseismic parameters, {DELTA}P and {DELTA}{nu}, which are used to accurately select red clump stars, can be derived from spectra using the change in the surface carbon to nitrogen ratio ([C/N]) caused by mixing during the red giant branch. This change in [C/N] can also impact the spectral energy distribution. In this study, we predict the {DELTA}P, {DELTA}{nu}, Teff and logg using 2MASS, AllWISE, Gaia, and Pan-STARRS data in order to select a clean sample of red clump stars. We achieve a contamination rate of ~20%, equivalent to what is achieved when selecting from Teff and logg derived from low resolution spectra. Finally, we present two red clump samples. One sample has a contamination rate of ~20% and ~405000 red clump stars. The other has a contamination of ~33% and ~2.6 million red clump stars which includes ~75000 stars at distances >10kpc. For |b|>30 degrees we find ~15000 stars with contamination rate of ~9%. The scientific potential of this catalog for studying the structure and formation history of the Galaxy is vast given that it includes millions of precise distances to stars in the inner bulge and distant halo where astrometric distances are imprecise.
- ID:
- ivo://CDS.VizieR/J/A+A/403/93
- Title:
- Photometry of AGB stars in NGC 185 and NGC 147
- Short Name:
- J/A+A/403/93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The tables represent results of an ongoing photometric survey of Local Group galaxies, using a four filter technique based on the method of Wing (1971, Proc. of the Conference on Late-Type Stars, ed. G.W. Lockwood and H.M. Dyck, KPNO Contribution 554, 145) to identify and characterise the late-type stellar content. Two narrow band filters centred on spectral features of TiO and CN allow us to distinguish between AGB stars of different chemistries [M-type (O-rich) and C-type (C-rich)]. The major parts of two dwarf galaxies, NGC 185 and NGC 147, were observed; 154 new AGB carbon stars in NGC 185 and 146 in NGC 147 were identified. All detected stars (called sample 1 in the paper) are included in the tables, with coordinates and photometric properties. All stars of sample 1 have photometry in the filters V and i. For all stars, which are in addition included in the smaller sample 2 (and have also photometry in the narrowband filters TiO and CN) the colour index (TiO-CN) is provided, too. In the tables a chemistry flag F marks in which classification group the star falls. All stars of sample 2 can have "c" for Carbon star, "o" for oxygen-rich M-type star or "r" for the rest. This correspond to the selection areas in Figure 4 of the paper. The flag for all stars of sample 1, which are not already included in sample 2 (only Vi-photometry) is "u" for unclassified.
- ID:
- ivo://CDS.VizieR/J/AJ/147/76
- Title:
- Photometry of M giant candidates in the Milky Way
- Short Name:
- J/AJ/147/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of 404 M giant candidates found in the UKIRT Infrared Deep Sky Survey (UKIDSS). The 2400deg^2^ available in the UKIDSS Large Area Survey Data Release 8 resolve M giants through a volume four times larger than that of the entire Two Micron All Sky Survey. Combining near-infrared photometry with optical photometry and proper motions from the Sloan Digital Sky Survey yields an M giant candidate catalog with less M dwarf and quasar contamination than previous searches for similarly distant M giants. Extensive follow-up spectroscopy of this sample will yield the first map of our Galaxy's outermost reaches over a large area of sky. Our initial spectroscopic follow-up of ~30 bright candidates yielded the positive identification of five M giants at distances ~20-90kpc. Each of these confirmed M giants have positions and velocities consistent with the Sagittarius stream. The fainter M giant candidates in our sample have estimated photometric distances ~200kpc (assuming [Fe/H]=0.0), but require further spectroscopic verification. The photometric distance estimates extend beyond the Milky Way's virial radius, and increase by ~50% for each 0.5dex decrease in assumed [Fe/H]. Given the number of M giant candidates, initial selection efficiency, and volume surveyed, we loosely estimate that at least one additional Sagittarius-like accretion event could have contributed to the hierarchical build-up of the Milky Way's outer halo.
- ID:
- ivo://CDS.VizieR/J/A+A/651/A102
- Title:
- Photometry of M31 globular cluster EXT8
- Short Name:
- J/A+A/651/A102
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We recently found the globular cluster (GC) EXT8 in M31 to have an extremely low metallicity of [Fe/H]=-2.91+/-0.04 using high-resolution spectroscopy. Here we present a colour-magnitude diagram (CMD) for EXT8, obtained with the Wide Field Camera 3 on board the Hubble Space Telescope. Compared with the CMDs of metal-poor Galactic GCs, we find that the upper red giant branch (RGB) of EXT8 is about 0.03mag bluer in F606W-F814W and slightly steeper, as expected from the low spectroscopic metallicity. The observed colour spread on the upper RGB is consistent with being caused entirely by the measurement uncertainties, and we place an upper limit of sigma(F606W-F814W)=0.015mag on any intrinsic colour spread. The corresponding metallicity spread can be up to sigma([Fe/H])=0.2dex or >0.7dex, depending on the isochrone library adopted. The horizontal branch (HB) is located mostly on the blue side of the instability strip and has a tail extending to at least M(F606W)=+3, as in the Galactic GC M15. We identify two candidate RR Lyrae variables and several UV-luminous post-HB/post-AGB star candidates, including one very bright (M(F300X)=-3.2) source near the centre of EXT8. The surface brightness of EXT8 out to a radius of 25 arcsec is well fitted by a Wilson-type profile with an ellipticity of epsilon=0.20, a semi-major axis core radius of 0.25", and a central surface brightness of 15.2mag per square arcsec in the F606W band, with no evidence of extra-tidal structure. Overall, EXT8 has properties consistent with it being a "normal", but very metal-poor GC, and its combination of relatively high mass and very low metallicity thus remains challenging to explain in the context of GC formation theories operating within the hierarchical galaxy assembly paradigm.
- ID:
- ivo://CDS.VizieR/J/A+A/497/497
- Title:
- Physical parameters from JHK flux
- Short Name:
- J/A+A/497/497
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The effective temperature scale of FGK stars, especially at the lowest metallicities remains a major problem in the chemical abundance analysis of metal-poor stars. We present a new implementation of the infrared flux method (IRFM) using the 2MASS catalogue.
- ID:
- ivo://CDS.VizieR/J/A+A/543/A45
- Title:
- Planets around metal-poor stars
- Short Name:
- J/A+A/543/A45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of about 700 extrasolar planets, so far, has lead to the first statistics concerning extrasolar planets. The presence of giant planets seems to depend on stellar metallicity and mass. For example, they are more frequent around metal-rich stars, with an exponential increase in planet occurrence rates with metallicity. We analyzed two samples of metal-poor stars (-2.0<[Fe/H]<0.0) to see if giant planets are indeed rare around these objects. Radial velocity datasets were obtained with two different spectrographs (HARPS and HIRES). Detection limits for these data, expressed in minimum planetary mass and period, are calculated. These produce trustworthy numbers for the planet frequency. A general Lomb Scargle (GLS) periodogram analysis was used together with a bootstrapping method to produce the detection limits. Planet frequencies were calculated based on a binomial distribution function within metallicity bins. Almost all hot Jupiters and most giant planets should have been found in these data. Hot Jupiters around metal-poor stars have a frequency lower than 1.0% at one sigma. Giant planets with periods up to 1800 days, however, have a higher frequency of 2.63^+2.5^_-0.89_%. Taking into account the different metallicities of the stars, we show that giant planets appear to be very frequent (4.48^+4.04^_-1.38_%) around stars with [Fe/H]>-0.7, while they are rare around stars with [Fe/H]<-0.7. We conclude that giant planet frequency is indeed a strong function of metallicity, even in the low-metallicity tail. However, the frequencies are most likely higher than previously thought.
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/2948
- Title:
- Polarimetry of 53 post-AGB stars
- Short Name:
- J/MNRAS/466/2948
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new optical broad-band (UBVRI) aperture polarimetric observations of 53 post-asymptotic giant branch (AGB) stars selected to exhibit a large near-infrared excess. 24 out of the 53 stars (45% of our sample) are presented for the first time. A statistical analysis shows four distinctive groups of polarized post-AGB stars: unpolarized or very lowly polarized (degree of polarization or DoP<1%), lowly polarized (1%<DoP<4%), moderately polarized (4%<DoP<8%) and highly polarized (DoP>8%). 23 out of the 53 (66%) belong to the first group, 10 (19%) to the second, five ( %) to the third and only three (6%) to the last group. Approximately 34%of our sample was found to be unpolarized objects, which is close to the percentage of round planetary nebulae. On average, the low and moderate groups show a wavelength-dependent polarization that increases towards shorter wavelengths, implying an intrinsic origin of the polarization, which signifies a Rayleigh-like scattering spectrum typical for non-symmetrical envelopes composed principally of small dust grains. The moderately polarized stars exhibit higher K-W3 and W1-W3 colour indices compared with the group of lowly polarized stars, suggesting a possible relation between DoP and mass-loss rate. Moreover, they are found to be systematically colder (redder in B-V), which may be associated with the condensation process close to these stars that results in a higher degree of polarization. We also provide evidence that multiple scattering in optically thin polar outflows is the mechanism that gives high DoP in post-AGB stars with bipolar or multi-polar envelopes.
