- ID:
- ivo://CDS.VizieR/J/ApJ/883/175
- Title:
- First release of the MaNGA Stellar Library (MaStar)
- Short Name:
- J/ApJ/883/175
- Date:
- 29 Nov 2021 07:46:33
- Publisher:
- CDS
- Description:
- We present the first release of the MaNGA Stellar Library (MaStar), which is a large, well-calibrated, high-quality empirical library covering the wavelength range 3622-10354{AA} at a resolving power of R~1800. The spectra were obtained using the same instrument as used by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) project, by piggybacking on the Sloan Digital Sky Survey (SDSS-IV)/Apache Point Observatory Galaxy Evolution Experiment 2-N (APOGEE-2N) observations. Compared to previous empirical libraries, the MaStar library will have a higher number of stars and a more comprehensive stellar-parameter coverage, especially of cool dwarfs, low-metallicity stars, and stars with different [{alpha}/Fe], achieved by a sophisticated target-selection strategy that takes advantage of stellar-parameter catalogs from the literature. This empirical library will provide a new basis for stellar-population synthesis and is particularly well suited for stellar-population analysis of MaNGA galaxies. The first version of the library contains 8646 high-quality per-visit spectra for 3321 unique stars. Compared to photometry, the relative flux calibration of the library is accurate to 3.9% in g-r, 2.7% in r-i, and 2.2% in i-z. The data are released as part of SDSS Data Release 15. We expect the final release of the library to contain more than 10000 stars.
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- ID:
- ivo://CDS.VizieR/J/AJ/159/187
- Title:
- First RVs with the EXPRES spectrograph: 51Peg
- Short Name:
- J/AJ/159/187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The EXtreme-PREcision Spectrograph (EXPRES) is an environmentally stabilized, fiber-fed, R=137500, optical spectrograph. It was recently commissioned at the 4.3m Lowell Discovery Telescope near Flagstaff, Arizona. The spectrograph was designed with a target radial-velocity (RV) precision of 30cm/s. In addition to instrumental innovations, the EXPRES pipeline, presented here, is the first on-sky, optical, fiber-fed spectrograph to employ many novel techniques-including an "extended flat" fiber used for wavelength-dependent quantum efficiency characterization of the CCD, a flat-relative optimal extraction algorithm, chromatic barycentric corrections, chromatic calibration offsets, and an ultra-precise laser frequency comb for wavelength calibration. We describe the reduction, calibration, and RV analysis pipeline used for EXPRES and present an example of our current sub-meter-per-second RV measurement precision, which reaches a formal, single-measurement error of 0.3m/s for an observation with a per-pixel signal-to-noise ratio of 250. These velocities yield an orbital solution on the known exoplanet host 51Peg that matches literature values with a residual rms of 0.895m/s.
- ID:
- ivo://CDS.VizieR/J/AJ/133/2097
- Title:
- FIRST "Winged" and X-shaped radio source candidates
- Short Name:
- J/AJ/133/2097
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A small number of double-lobed radio galaxies (17 from our own census of the literature) show an additional pair of low surface brightness "wings," thus forming an overall X-shaped appearance. Using the VLA FIRST survey database, we are compiling a large sample of winged and X-shaped radio sources for such studies. As a first step toward this goal, an initial sample of 100 new candidate objects of this type are presented in this paper.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A199
- Title:
- Fit parameters & ephemerides of 650 mCP stars
- Short Name:
- J/A+A/622/A199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Magnetic, chemically peculiar stars are known for exhibiting surface abundance inhomogeneities (chemical spots) that lead to photometric and spectroscopic variability with the rotation period. It is commonly assumed that the surface structures are causally connected with the global magnetic field that dominates the photospheric and subphotospheric layers of these stars. As a rule, the observed magnetic fields show a simple dipole-like geometry, with the magnetic axis being noncollinear to the rotational one. The present study aims at detecting underlying patterns in the distribution of photometric spots in a sample of 650 magnetic, chemically peculiar stars and examines their link to the magnetic field topology. Photometric time-series observations from the ASAS-3 archive were employed to inspect the light-curve morphology of our sample stars and divide them into representative classes described using a principal component analysis. Theoretical light curves were derived from numerous simulations assuming different spot parameters and following the symmetry of a simple dipole magnetic field. These were subsequently compared with the observed light curves. The results from our simulations are in contradiction with the observations and predict a much higher percentage of double-wave light curves than is actually observed. We thereby conclude that the distribution of the chemical spots does not follow the magnetic field topology, which indicates that the role of the magnetic field in the creation and maintenance of the surface structures may be more subsidiary than what is predicted by theoretical studies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/399/432
- Title:
- Fitted UBV magnitude for MS stars
- Short Name:
- J/MNRAS/399/432
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We fit the colour-magnitude diagrams of stars between the zero-age main-sequence and terminal-age main sequence in young clusters and associations. The ages we derive are a factor of 1.5-2 longer than the commonly used ages for these regions, which are derived from the positions of pre-main-sequence stars in colour-magnitude diagrams. From an examination of the uncertainties in the main-sequence and pre-main-sequence models, we conclude that the longer age scale is probably the correct one, which implies that we must revise upwards the commonly used ages for young clusters and associations. Such a revision would explain the discrepancy between the observational lifetimes of protoplanetary discs and theoretical calculations of the time to form planets. It would also explain the absence of clusters with ages between 5 and 30Myr.
- ID:
- ivo://CDS.VizieR/J/ApJ/704/1570
- Title:
- Fitting LINERs within the AGN family
- Short Name:
- J/ApJ/704/1570
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we study the nuclear obscuration of galaxies hosting low ionization narrow emission regions (LINERs) based on their X-ray and optical emission. They show column densities at soft energies (0.5-2keV) mostly related to the diffuse emission around the active galactic nucleus (AGN), showing a correlation with the optical extinction. Column densities at hard energies (2-10keV) seem to be much higher than what would be expected from the optical extinction. They might be associated with the inner regions of the AGN, buried at optical wavelengths.
- ID:
- ivo://CDS.VizieR/J/AJ/158/63
- Title:
- Five new transiting hot Jupiters:HATS-54b-HATS-58b
- Short Name:
- J/AJ/158/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery by the HATSouth project of five new transiting hot Jupiters (HATS-54b through HATS-58Ab). HATS-54b, HATS-55b, and HATS-58Ab are prototypical short-period (P=2.5-4.2 days, R_p_~1.1-1.2 R_J_) hot Jupiters that span effective temperatures from 1350 to 1750 K, putting them in the proposed region of maximum radius inflation efficiency. The HATS-58 system is composed of two stars, HATS-58A and HATS-58B, which are detected thanks to Gaia DR2 data and which we account for in the joint modeling of the available data-with this, we are led to conclude that the hot Jupiter orbits the brighter HATS-58A star. HATS-57b is a short-period (2.35 day), massive (3.15 M_J_), 1.14 R_J_, dense (2.65+/-0.21 g/cm^3^) hot Jupiter orbiting a very active star (2% peak-to-peak flux variability). Finally, HATS-56b is a short-period (4.32 day), highly inflated hot Jupiter (1.7 R_J_, 0.6 M_J_), which is an excellent target for future atmospheric follow-up, especially considering the relatively bright nature (V=11.6) of its F dwarf host star. This latter exoplanet has another very interesting feature: the radial velocities show a significant quadratic trend. If we interpret this quadratic trend as arising from the pull of an additional planet in the system, we obtain a period of P_c_=815_-143_^+253^ days for the possible planet HATS-56c, and a minimum mass of M_c_sini_c_=5.11+/-0.94 M_J_. The candidate planet HATS-56c would have a zero-albedo equilibrium temperature of T_eq_=332+/-50 K, and thus would be orbiting close to the habitable zone of HATS-56. Further radial-velocity follow-up, especially over the next two years, is needed to confirm the nature of HATS-56c.
- ID:
- ivo://CDS.VizieR/J/AJ/145/68
- Title:
- Five new transit light curves of TrES-3
- Short Name:
- J/AJ/145/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Five newly observed transit light curves of the TrES-3 planetary system are presented. Together with other light-curve data from the literature, 23 transit light curves in total, which cover an overall timescale of 911 epochs, have been analyzed through a standard procedure. From these observational data, the system's orbital parameters are determined and possible transit timing variations (TTVs) are investigated. Given that a null TTV produces a fit with reduced {chi}^2^=1.52, our results agree with previous work, that TTVs might not exist in these data. However, a one-frequency oscillating TTV model, giving a fit with a reduced {chi}^2^=0.93, does possess a statistically higher probability. It is thus concluded that future observations and dynamical simulations for this planetary system will be very important.
- ID:
- ivo://CDS.VizieR/J/AJ/151/142
- Title:
- Five years of blazar observations with VERITAS
- Short Name:
- J/AJ/151/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Between the beginning of its full-scale scientific operations in 2007 and 2012, the VERITAS Cherenkov telescope array observed more than 130 blazars; of these, 26 were detected as very-high-energy (VHE; E>100 GeV) {gamma}-ray sources. In this work, we present the analysis results of a sample of 114 undetected objects. The observations constitute a total live-time of ~570 hr. The sample includes several unidentified Fermi-Large Area Telescope (LAT) sources (located at high Galactic latitude) as well as all the sources from the second Fermi-LAT catalog (Nolan et al. 2012, J/ApJS/199/31) that are contained within the field of view of the VERITAS observations. We have also performed optical spectroscopy measurements in order to estimate the redshift of some of these blazars that do not have spectroscopic distance estimates. We present new optical spectra from the Kast instrument on the Shane telescope at the Lick observatory for 18 blazars included in this work, which allowed for the successful measurement or constraint on the redshift of four of them. For each of the blazars included in our sample, we provide the flux upper limit in the VERITAS energy band. We also study the properties of the significance distributions and we present the result of a stacked analysis of the data set, which shows a 4{sigma} excess.
- ID:
- ivo://CDS.VizieR/J/A+A/561/A87
- Title:
- FLAMES observations of Terzan 8
- Short Name:
- J/A+A/561/A87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive globular clusters (GCs) contain at least two generations of stars with slightly different ages and clearly distinct light elements abundances. The Na-O anticorrelation is the best studied chemical signature of multiple stellar generations. Low-mass clusters appear instead to be usually chemically homogeneous. We are investigating low-mass GCs to understand what is the lower mass limit where multiple populations can form, mainly using the Na and O abundance distribution. We used VLT/FLAMES spectra of giants in the low-mass, metal-poor GC Terzan 8, belonging to the Sagittarius dwarf galaxy, to determine abundances of Fe, O, Na, alpha-, Fe-peak, and neutron-capture elements in six stars observed with UVES and 14 observed with GIRAFFE. The average metallicity is [Fe/H]=-2.27+/-0.03 (rms=0.08), based on the six high-resolution UVES spectra. Only one star, observed with GIRAFFE, shows an enhanced abundance of Na and we tentatively assign it to the second generation. In this cluster, at variance with what happens in more massive GCs, the second generation seems to represent at most a small minority fraction. We discuss the implications of our findings, comparing Terzan 8 with the other Sgr dSph GCs, to GCs and field stars in the Large Magellanic Cloud, Fornax, and in other dwarfs galaxies.
