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3421. Spectral lines of BK Peg and BW Aqr
ID:
ivo://CDS.VizieR/J/A+A/516/A42
Title:
Spectral lines of BK Peg and BW Aqr
Short Name:
J/A+A/516/A42
Date:
21 Oct 2021
Publisher:
CDS
Description:
Double-lined, detached eclipsing binaries are our main source for accurate stellar masses and radii. In this paper we focus on the 1.15-1.70M_{sun}_ interval where convective core overshoot is gradually ramped up in theoretical evolutionary models. We aim to determine absolute dimensions and abundances for the F-type detached eclipsing binary BK Peg, and to perform a detailed comparison with results from recent stellar evolutionary models, including a sample of previously studied systems with accurate parameters.
3422. Spectral observations of symbiotic LL Cas
ID:
ivo://CDS.VizieR/J/A+A/479/529
Title:
Spectral observations of symbiotic LL Cas
Short Name:
J/A+A/479/529
Date:
21 Oct 2021
Publisher:
CDS
Description:
All tables contain the results of the spectral and photometric observations of the symbiotic star LL Cas. Observations were carried out within 1986-2006 with a slit spectrograph attached to the 0.7-m telescope of the Fessenkov Astrophysical Institute (Almaty, Kazakhstan). Some photoelectric observations of LL Cas with broad-band filters were carried out on a photoelectric polarimeter mounted on the 1-m Zeiss telescope (Assy-Turgen, Kazakhstan).
3423. Spectra of a rare low-mass Wolf-Rayet star in LMC
ID:
ivo://CDS.VizieR/J/ApJ/888/54
Title:
Spectra of a rare low-mass Wolf-Rayet star in LMC
Short Name:
J/ApJ/888/54
Date:
25 Oct 2021 10:12:43
Publisher:
CDS
Description:
We report the serendipitous discovery of an object, UVQSJ060819.93-715737.4, with a spectrum dominated by extremely intense, narrow CII emission lines. The spectrum is similar to those of the very rare, late-type [WC11] low-mass Wolf-Rayet stars. Despite the recognition of these stars as a distinct class decades ago, there remains barely a handful of Galactic members, all of which are also planetary-nebula central stars. Although no obvious surrounding nebulosity is present in J0608, [OII], [NII], and [SII] emission suggest the presence of an inconspicuous, low-excitation nebula. There is low-amplitude incoherent photometric variability on timescales of days to years, as well as numerous prominent P Cygni profiles, implying mass loss. There are indications of a binary companion. The star is located on the outskirts of the LMC, and the observed radial velocity (~+250km/s) and proper motion strongly suggest membership. If indeed an LMC member, this is the first extragalactic late [WC] star, and the first with an accurately determined luminosity, as the Galactic examples are too distant for precise parallax determinations. A high-quality, broad-coverage spectrum of the prototype of the late [WC] class, CPD -56 8032, is also presented. We discuss different excitation mechanisms capable of producing the great strength of the CII emission. Numerous autoionizing levels of C II are definitely populated by processes other than dielectronic recombination. Despite the spectacular emission spectra, observational selection makes objects such as these difficult to discover. Members of the [WC11] class may in fact be considerably more common than the handful of previously known late [WC] stars.
3424. Spectra of 73 asteroids
ID:
ivo://CDS.VizieR/J/A+A/630/A141
Title:
Spectra of 73 asteroids
Short Name:
J/A+A/630/A141
Date:
21 Oct 2021
Publisher:
CDS
Description:
Several primitive families in the inner region of the main asteroid belt were identified as potential sources for two near-Earth asteroids (NEAs), (101955) Bennu and (162173) Ryugu, targets of the sample-return missions OSIRIS-REx and Hayabusa2, respectively. Four of the families, located at high proper inclinations (i>10{deg}), have not yet been compositionally studied: Klio, Chaldaea, Chimaera, and Svea. We want to characterize and analyze these families within the context of our PRIMitive Asteroid Spectroscopic Survey (PRIMASS), in order to complete the puzzle of the origins of the two NEAs. We obtained visible spectra (0.5-0.9um) of a total of 73 asteroids within the Klio, Chaldaea, Chimaera, and Svea collisional families, using the instrument OSIRIS at the 10.4m Gran Telescopio Canarias. We performed a taxonomical classification of these objects, and an analysis of the possible presence of absorption bands related to aqueous alterations, comparing the results with already studied primitive families in the inner main belt. We present here reflectance spectra for 30 asteroids in the Klio family, 15 in Chaldaea, 20 in Chimaera, and 8 in Svea. We show that Klio, Chaldaea, and Chimaera members have moderately red spectral slopes, with aqueous alteration absorption bands centered around 0.7um, characteristic of the group of primitive families known as Erigone-like. In contrast, Svea shows no 0.7um features, and neutral and blue spectral slopes, and thus is a Polana-like family. While all four families might be related to (162173) Ryugu, the only family studied in this work that might be related to (101955) Bennu is Svea.
3425. Spectra of IRAS 17449+2320
ID:
ivo://CDS.VizieR/J/A+A/659/A35
Title:
Spectra of IRAS 17449+2320
Short Name:
J/A+A/659/A35
Date:
04 Mar 2022 00:58:00
Publisher:
CDS
Description:
We report the first detection of the magnetic field in a star of FS CMa type, a subgroup of objects characterized by the B[e] phenomenon. The split of magnetically sensitive lines in IRAS 17449+2320 determines the magnetic field modulus of 6.2+/-0.2kG. Spectral lines and their variability reveal the presence of a B-type spectrum and a hot continuum source in the visible. The hot source confirms GALEX UV photometry. Because there is a lack of spectral lines for the hot source in the visible, the spectral fitting gives only the lower temperature limit of the hot source, which is 50000K, and the upper limit for the B-type star of 11100K. The V/R ratio of the Halpha line shows quasiperiodic behavior on timescale of 800 days. We detected a strong red-shifted absorption in the wings of Balmer and OI lines in some of the spectra. The absorption lines of helium and other metals show no, or very small, variations, indicating unusually stable photospheric regions for FS CMa stars. We detected two events of material infall, which were revealed to be discrete absorption components of resonance lines. The discovery of the strong magnetic field together with the Gaia measurements of the proper motion show that the most probable nature of this star is that of a post-merger object created after the leaving the binary of the birth cluster. Another possible scenario is a magnetic Ap star around Terminal-Age Main Sequence (TAMS). On the other hand, the strong magnetic field defies the hypothesis that IRAS 17449+2320 is an extreme classical Be star. Thus, IRAS 17449+2320 provides a pretext for exploring a new explanation of the nature of FS CMa stars or, at least, a group of stars with very similar spectral properties.
3426. Spectra of SN 2017eaw 545 & 900 days after explosion
ID:
ivo://CDS.VizieR/J/ApJ/900/11
Title:
Spectra of SN 2017eaw 545 & 900 days after explosion
Short Name:
J/ApJ/900/11
Date:
14 Mar 2022 07:13:15
Publisher:
CDS
Description:
SN 2017eaw, the tenth supernova observed in NGC6946, was a normal Type II-P supernova with an estimated 11-13M{sun} red supergiant progenitor. Here we present nebular-phase spectra of SN 2017eaw at +545 and +900days post-max, extending approximately 50-400days past the epochs of previously published spectra. While the +545day spectrum is similar to spectra taken between days +400 and +493, the +900day spectrum shows dramatic changes both in spectral features and emission-line profiles. The H{alpha} emission is flat-topped and boxlike with sharp blue and red profile velocities of ~-8000 and +7500km/s. These late-time spectral changes indicate strong circumstellar interaction with a mass-loss shell, expelled ~1700yr before explosion. SN 2017eaw's +900day spectrum is similar to those seen for SN2004et and SN2013ej observed 2-3yr after explosion. We discuss the importance of late-time monitoring of bright SNeII-P and the nature of presupernova mass-loss events for SNII-P evolution.
3427. Spectra of 28 stars in Price-Whelan 1 association
ID:
ivo://CDS.VizieR/J/ApJ/887/115
Title:
Spectra of 28 stars in Price-Whelan 1 association
Short Name:
J/ApJ/887/115
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report spectroscopic measurements of stars in the recently discovered young stellar association Price-Whelan 1 (PW1), which was found in the vicinity of the Leading Arm (LA) of the Magellanic Stream (MS). We obtained Magellan+MIKE high-resolution spectra of the 28 brightest stars in PW 1 and used The Cannon to determine their stellar parameters. We find that the mean metallicity of PW1 is [Fe/H]=-1.23 with a small scatter of 0.06dex and the mean RV is V_hel_=276.7km/s with a dispersion of 11.0km/s. Our results are consistent in T_eff_, logg, and [Fe/H] with the young and metal-poor characteristics (116Myr and [Fe/H]=-1.1) determined for PW1 from our discovery paper. We find a strong correlation between the spatial pattern of the PW1 stars and the LA II gas with an offset of -10.15{deg} in L_MS_ and +1.55{deg} in B_MS_. The similarity in metallicity, velocity, and spatial patterns indicates that PW1 likely originated in LA II. We find that the spatial and kinematic separation between LA II and PW1 can be explained by ram pressure from Milky Way (MW) gas. Using orbit integrations that account for the LMC and MW halo and outer disk gas, we constrain the halo gas density at the orbital pericenter of PW1 to be n_halo_(17kpc)=2.7_-2.0_^+3.4^x10^-3^atoms/cm^3^ and the disk gas density at the midplane at 20kpc to be n_disk_(20kpc,0)=6.0_-2.0_^+1.5^x10^-2^atoms/cm^3^. We, therefore, conclude that PW 1 formed from the LA II of the MS, making it a powerful constraint on the MW-Magellanic interaction.
3428. Spectrophotometric parallaxes with linear models
ID:
ivo://CDS.VizieR/J/AJ/158/147
Title:
Spectrophotometric parallaxes with linear models
Short Name:
J/AJ/158/147
Date:
07 Jan 2022 11:19:14
Publisher:
CDS
Description:
With contemporary infrared spectroscopic surveys like APO Galactic Evolution Experiment (APOGEE), red-giant stars can be observed to distances and extinctions at which Gaia parallaxes are not highly informative. Yet the combination of effective temperature, surface gravity, composition, and age-all accessible through spectroscopy - determines a giant's luminosity. Therefore spectroscopy plus photometry should enable precise spectrophotometric distance estimates. Here we use the overlap of APOGEE, Gaia, the Two Micron All Sky Survey (2MASS), and the Wide-field Infrared Survey Explorer (WISE) to train a data-driven model to predict parallaxes for red-giant branch stars with 0<logg=<2.2 (more luminous than the red clump). We employ (the exponentiation of) a linear function of APOGEE spectral pixel intensities and multiband photometry to predict parallax spectrophotometrically. The model training involves no logarithms or inverses of the Gaia parallaxes, and needs no cut on the Gaia parallax signal-to-noise ratio. It includes an L1 regularization to zero out the contributions of uninformative pixels. The training is performed with leave-out subsamples such that no star's astrometry is used even indirectly in its spectrophotometric parallax estimate. The model implicitly performs a reddening and extinction correction in its parallax prediction, without any explicit dust model. We assign to each star in the sample a new spectrophotometric parallax estimate; these parallaxes have uncertainties of less than 15%, depending on data quality, which is more precise than the Gaia parallax for the vast majority of targets, and certainly any stars more than a few kiloparsec distance. We obtain 10% distance estimates out to heliocentric distances of 20 kpc, and make global maps of the Milky Way's disk.
3429. Spectrophotometric redshifts of GOODS galaxies
ID:
ivo://CDS.VizieR/J/ApJ/883/157
Title:
Spectrophotometric redshifts of GOODS galaxies
Short Name:
J/ApJ/883/157
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the accuracy of 4000{AA}/Balmer-break based redshifts by combining Hubble Space Telescope (HST) grism data with photometry. The grism spectra are from the Probing Evolution And Reionization Spectroscopically survey with HST using the G800L grism on the Advanced Camera for Surveys. The photometric data come from a compilation by the 3D-HST collaboration of imaging from multiple surveys (notably, the Cosmic Assembly Near-infrared Deep Extragalactic Survey (CANDELS) and 3D-HST). We show evidence that spectrophotometric redshifts (SPZs) typically improve the accuracy of photometric redshifts by ~17%-60%. Our SPZ method is a template-fitting-based routine that accounts for correlated data between neighboring points within grism spectra via the covariance matrix formalism and also accounts for galaxy morphology along the dispersion direction. We show that the robustness of the SPZ is directly related to the fidelity of the D4000 measurement. We also estimate the accuracy of continuum-based redshifts, i.e., for galaxies that do not contain strong emission lines, based on the grism data alone ({sigma}_{Delta}z/(1+z)_^NMAD^<~0.06). Given that future space-based observatories like Wide Field InfraRed Survey Telescope and Euclid will spend a significant fraction of time on slitless spectroscopic observations, we estimate number densities for objects with |{Delta}z/(1+z_s_)|<=0.02. We predict ~700-4400 galaxies degree^-2^ for galaxies with D4000>1.1 and |{Delta}z/(1+z_s_)|<=0.02 to a limiting depth of i_AB_=24mag. This is especially important in the absence of an accompanying rich photometric data set like the existing one for the CANDELS fields, where redshift accuracy from future surveys will rely only on the presence of a feature like the 4000{AA}/Balmer breaks or the presence of emission lines within the grism spectra.
3430. Spectrophotometric standard cand. photometry
ID:
ivo://CDS.VizieR/J/MNRAS/501/2848
Title:
Spectrophotometric standard cand. photometry
Short Name:
J/MNRAS/501/2848
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Johnson-Kron-Cousins BVRI photometry of 228 candidate spectrophotometric standard stars for the external (absolute) flux calibration of Gaia data. The data were gathered as part of a 10-yr observing campaign with the goal of building the external grid of flux standards for Gaia and we obtained absolute photometry, relative photometry for constancy monitoring, and spectrophotometry. Preliminary releases of the flux tables were used to calibrate the first two Gaia releases. This paper focuses on the imaging frames observed in good sky conditions (about 9100). The photometry will be used to validate the ground-based flux tables of the Gaia spectrophotometric standard stars and to correct the spectra obtained in non-perfectly photometric observing conditions for small zero-point variations. The absolute photometry presented here is tied to the Landolt standard stars system to ~1 per cent or better, depending on the photometric band. Extensive comparisons with various literature sources show an overall ~1 per cent agreement, which appears to be the current limit in the accuracy of flux calibrations across various samples and techniques in the literature. The Gaia photometric precision is presently of the order of 0.1 per cent or better, thus various ideas for the improvement of photometric calibration accuracy are discussed.