- ID:
- ivo://CDS.VizieR/J/ApJ/686/1280
- Title:
- Discovery of hot subdwarf companion to FY CMa
- Short Name:
- J/ApJ/686/1280
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The rapid rotation of Be stars may be caused in some cases by past mass and angular momentum accretion in an interacting binary in which the mass donor is currently viewed as a small, hot subdwarf stripped of its outer envelope. Here we report on the spectroscopic detection of such a subdwarf in the Be binary system FY Canis Majoris from the analysis of data acquired by the IUE spacecraft and KPNO Coude Feed Telescope over the course of 16 and 21yr, respectively. We present a double-lined spectroscopic orbit for the binary based on radial velocities from the IUE spectra and use the orbital solutions with a Doppler tomography algorithm to reconstruct the components' UV spectra. The subdwarf is hot (T_eff_=45+/-5kK) and has a mass of about 1.3M_{sun}_ and a radius of about 0.6R_{sun}_. It contributes about 4% as much flux as the Be star does in the FUV. We also present observations of the H{alpha} and HeI{lambda}6678 emission features that are formed in the circumstellar disk of the Be star.
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4502. Discovery of PNe in M82
- ID:
- ivo://CDS.VizieR/J/ApJ/697/1138
- Title:
- Discovery of PNe in M82
- Short Name:
- J/ApJ/697/1138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using an [OIII]{lambda}5007 on-band/off-band filter technique, we identify 109 planetary nebulae (PNe) candidates in the edge-on spiral galaxy M 82, using the FOCAS instrument at the 8.2m Subaru Telescope. The use of ancillary high-resolution Hubble Space Telescope Advanced Camera for Surveys H{alpha} imaging aided in confirming these candidates, helping to discriminate PNe from contaminants such as supernova remnants and compact HII regions. Once identified, these PNe reveal a great deal about the host galaxy; our analysis covers kinematics, stellar distribution, and distance determination. Radial velocities were determined for 94 of these PNe using a method of slitless spectroscopy, from which we obtain a clear picture of the galaxy's rotation.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A73
- Title:
- Discovery of the directly imaged planet YSES 2b
- Short Name:
- J/A+A/648/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To understand the origin and formation pathway of wide-orbit gas giant planets, it is necessary to expand the limited sample of these objects. The mass of exoplanets derived with spectrophotometry, however, varies strongly as a function of the age of the system and the mass of the primary star. By selecting stars with similar ages and masses, the Young Suns Exoplanet Survey (YSES) aims to detect and characterize planetary-mass companions to solar-type host stars in the Scorpius-Centaurus association. Our survey is carried out with VLT/SPHERE with short exposure sequences on the order of 5-min per star per filter. The subtraction of the stellar point spread function (PSF) is based on reference star differential imaging (RDI) using the other targets (with similar colors and magnitudes) in the survey in combination with principal component analysis. Two astrometric epochs that are separated by more than one year are used to confirm co-moving companions by proper motion analysis. We report the discovery of YSES 2b, a co-moving, planetary-mass companion to the K1 star YSES 2 (TYC 8984-2245-1, 2MASS J11275535-6626046). The primary has a Gaia EDR3 distance of 110pc, and we derive a revised mass of 1.1M_{sun}_ and an age of approximately 14Myr. We detect the companion in two observing epochs southwest of the star at a position angle of 205{deg} and with a separation of ~1.05", which translates to a minimum physical separation of 115au at the distance of the system. Photometric measurements in the H and Ks bands are indicative of a late L spectral type, similar to the innermost planets around HR 8799. We derive a photometric planet mass of 6.3^+1.6^_-0.9_M_{Jup}_ using AMES-COND and AMES-dusty evolutionary models; this mass corresponds to a mass ratio of q=(0.5+/-0.1)% with the primary. This is the lowest mass ratio of a direct imaging planet around a solar-type star to date. We discuss potential formation mechanisms and find that the current position of the planet is compatible with formation by disk gravitational instability, but its mass is lower than expected from numerical simulations. Formation via core accretion must have occurred closer to the star, yet we do not find evidence that supports the required outward migration, such as via scattering off another undiscovered companion in the system. We can exclude additional companions with masses greater than 13M_{Jup}_ in the full field of view of the detector (0.15"<{rho}<5.50"), at 0.5" we can rule out further objects that are more massive than 6M_{Jup}_, and for projected separations {rho}>2arcsec we are sensitive to planets with masses as low as 2M_{Jup}_. YSES 2b is an ideal target for follow-up observations to further the understanding of the physical and chemical formation mechanisms of wide-orbit Jovian planets. The YSES strategy of short snapshot observations (<=5min) and PSF subtraction based on a large reference library proves to be extremely efficient and should be considered for future direct imaging surveys.
- ID:
- ivo://CDS.VizieR/J/ApJ/734/98
- Title:
- DISCS. II. Southern sky disk data
- Short Name:
- J/ApJ/734/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second in a series of papers based on data from DISCS, a Submillimeter Array observing program aimed at spatially and spectrally resolving the chemical composition of 12 protoplanetary disks. We present data on six Southern sky sources -IM Lup, SAO 206462 (HD 135344b), HD 142527, AS 209, AS 205, and V4046 Sgr- which complement the six sources in the Taurus star-forming region reported previously. CO 2-1 and HCO^+^ 3-2 emission are detected and resolved in all disks and show velocity patterns consistent with Keplerian rotation. Where detected, the emission from DCO^+^ 3-2, N_2_H^+^ 3-2, H_2_CO 3_0 3_-2_0 2_ and 4_1 4_-3_1 3_, HCN 3-2, and CN 2_3 3/4/2_-1_2 2/3/1_ are also generally spatially resolved. The detection rates are highest toward the M and K stars, while the F star SAO 206462 has only weak CN and HCN emission, and H2CO alone is detected toward HD 142527.
- ID:
- ivo://CDS.VizieR/J/ApJ/720/480
- Title:
- DISCS. I. Taurus protoplanetary disk data
- Short Name:
- J/ApJ/720/480
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemistry plays an important role in the structure and evolution of protoplanetary disks, with implications for the composition of comets and planets. This is the first of a series of papers based on data from DISCS (Disk Imaging Survey of Chemistry with SMA), a Submillimeter Array survey of the chemical composition of protoplanetary disks. The six Taurus sources in the program (DM Tau, AA Tau, LkCa 15, GM Aur, CQ Tau, and MWC 480) range in stellar spectral type from M1 to A4 and offer an opportunity to test the effects of stellar luminosity on the disk chemistry. The disks were observed in 10 different lines at ~3" resolution and an rms of ~100mJy/beam at ~0.5km/s.
- ID:
- ivo://CDS.VizieR/J/A+A/598/A85
- Title:
- Disentangled spectra of R145
- Short Name:
- J/A+A/598/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first SB2 orbital solution and disentanglement of the massive Wolf-Rayet binary R145 (P=159d) located in the Large Magellanic Cloud. The primary was claimed to have a stellar mass greater than 300M_{sun}_, making it a candidate for the most massive star known. While the primary is a known late type, H-rich Wolf-Rayet star (WN6h), the secondary could not be so far unambiguously detected. Using moderate resolution spectra, we are able to derive accurate radial velocities for both components. By performing simultaneous orbital and polarimetric analyses, we derive the complete set of orbital parameters, including the inclination. The spectra are disentangled and spectroscopically analyzed, and an analysis of the wind-wind collision zone is conducted.
- ID:
- ivo://CDS.VizieR/J/MNRAS/492/L40
- Title:
- Disentangling cataclysmic variables in Gaia DR2
- Short Name:
- J/MNRAS/492/L40
- Date:
- 07 Dec 2021 09:36:41
- Publisher:
- CDS
- Description:
- Cataclysmic Variables (CVs) are interacting binaries consisting of at least three components that control their colour and magnitude. Using Gaia we here investigate the influence of the physical properties of these binaries on their position in the Hertzsprung-Russell diagram (HR-diagram). The CVs are on average located between the main sequence and the white dwarf regime, the maximum density being at G_BP_-G_RP_~=0.56 and G_abs_~10.15. We nd a trend of the orbital period with colour and absolute brightness: with decreasing period, the CVs become bluer and fainter. We also identify the location of the various CV sub-types in the HR-diagram and discuss the possible location of detached CVs, going through the orbital period gap.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/L3
- Title:
- Disilicon carbide (SiCSi) discovery in CW Leo
- Short Name:
- J/ApJ/806/L3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery in space of a disilicon species, SiCSi, from observations between 80 and 350GHz with the IRAM 30m radio telescope. Owing to the close coordination between laboratory experiments and astrophysics, 112 lines have now been detected in the carbon-rich star CW Leo. The derived frequencies yield improved rotational and centrifugal distortion constants up to sixth order. From the line profiles and interferometric maps with the Submillimeter Array, the bulk of the SiCSi emission arises from a region of 6" in radius. The derived abundance is comparable to that of SiC_2_. As expected from chemical equilibrium calculations, SiCSi and SiC_2_ are the most abundant species harboring a Si-C bond in the dust formation zone and certainly both play a key role in the formation of SiC dust grains.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A104
- Title:
- Disk and halo stars C, O and Fe abundances
- Short Name:
- J/A+A/630/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundances of carbon, oxygen, and iron in late-type stars are important parameters in exoplanetary and stellar physics, as well as key tracers of stellar populations and Galactic chemical evolution. However, standard spectroscopic abundance analyses can be prone to severe systematic errors, by the assumption that the stellar atmosphere is one-dimensional (1D) and hydrostatic, and by ignoring departures from local thermodynamic equilibrium (LTE). To address this, we carry out 3D non-LTE radiative transfer calculations for CI and OI, and 3D LTE radiative transfer calculations for FeII, across the stagger-grid of 3D hydrodynamic model atmospheres. The absolute 3D non-LTE versus 1D LTE abundance corrections can be as severe as ~0.3dex for CI lines in low-metallicity F dwarfs, and ~0.6dex for OI lines in high-metallicity F dwarfs. The 3D LTE versus 1D LTE abundance corrections for FeII lines are less severe, typically less than +0.15dex. We use the corrections in a re-analysis of carbon, oxygen, and iron in 187 F and G dwarfs in the Galactic disk and halo. Applying the differential 3D non-LTE corrections to 1D LTE abundances visibly reduces the scatter in the abundance plots. The thick disk and high- halo population rise in carbon and oxygen with decreasing metallicity, reaching a maximum of [C/Fe]~=0.2 and a plateau of [O/Fe]~=0.6 at [Fe/H]~=~1.0. The low- halo population is qualitatively similar, albeit offset towards lower metallicities and with larger scatter. Nevertheless, these populations overlap in the [C/O] versus [O/H] plane, decreasing to a plateau of [C/O]~=0.6 below [O/H]~=1.0. In the thin-disk, stars having confirmed planet detections tend to have higher values of C/O at given [O/H]; this potential signature of planet formation is only apparent after applying the abundance corrections to the 1D LTE results. Our grids of line-by-line abundance corrections are publicly available and can readily be used to improve the accuracy of spectroscopic analyses of late-type stars.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A149
- Title:
- Disk and halo stars C, O and Fe abundances (Amarsi+, 2019)
- Short Name:
- J/A+A/630/A149
- Date:
- 27 Sep 2019 05:42:26
- Publisher:
- CDS
- Description:
- Spectrum synthesis calculations were performed on four different families of model atmospheres: 3D hydrodynamic model atmospheres from the STAGGER-grid (Magic et al. 2013A&A...557A..26M, Cat. J/A+A/557/A26); 1D model atmospheres determined by averaging the <3D> STAGGER model atmospheres (henceforth <3D> model atmospheres; Magic et al. 2013A&A...560A...8M, Cat. J/A+A/560/A8); theoretical 1D hydrostatic model atmospheres from the ATMO-grid (the 1D equivalent of the STAGGER-grid, see Appendix A of Magic et al. 2013A&A...557A..26M, Cat. J/A+A/557/A26); and theoretical 1D hydrostatic model atmospheres from the MARCS-grid (Gustafsson et al. 2008A&A...486..951G). Table1 contains the line parameters that were adopted for the grids of abundance corrections. Table2 contains the 3D non-LTE versus 1D LTE abundance corrections for CI lines. Table3 contains the 3D non-LTE versus 1D LTE abundance corrections for OI lines. Table4 contains the 3D LTE versus 1D LTE abundance corrections for FeII lines. Table5 contains the 1D non-LTE versus 1D LTE abundance corrections for CI lines. Table6 contains the 1D non-LTE versus 1D LTE abundance corrections for OI lines. Table7 contains the stellar parameters and abundances for the 187 sample stars.