- ID:
- ivo://CDS.VizieR/J/other/NatAs/5.684
- Title:
- CH3OH in the HD100546 disk
- Short Name:
- J/other/NatAs/5.
- Date:
- 17 Jan 2022 00:30:51
- Publisher:
- CDS
- Description:
- Quantifying the composition of the material in protoplanetary disks is paramount to determining the potential for exoplanetary systems to produce and support habitable environments. When considering potential habitability, complex organic molecules are of relevance, key among which is methanol (CH_3_OH). Methanol primarily forms at low temperatures via the hydrogenation of CO ice on the surface of icy dust grains and is a necessary basis for the formation of more complex species such as amino acids and proteins. We report the detection of CH_3_OH in a disk around a young, luminous A-type star, HD 100546. This disk is warm and therefore does not host an abundant reservoir of CO ice. We argue that the CH_3_OH cannot form in situ, and hence this disk has probably inherited complex-organic-molecule-rich ice from an earlier cold dark cloud phase. This is strong evidence that at least some interstellar organic material survives the disk formation process and can then be incorporated into forming planets, moons and comets. Therefore, crucial pre-biotic chemical evolution already takes place in dark star-forming clouds.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/638/A59
- Title:
- delta Scuti stars with TESS
- Short Name:
- J/A+A/638/A59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Thanks to high-precision photometric data legacy from space telescopes like CoRoT and Kepler, the scientific community could detect and characterize the power spectra of hundreds of thousands of stars. Using the scaling relations, it is possible to estimate masses and radii for solar-type pulsators. However, these stars are not the only kind of stellar objects that follow these rules: delta Scuti stars seem to be characterized with seismic indexes such as the large separation. Thanks to long-duration high-cadence TESS light curves, we analysed more than two thousand of this kind of classical pulsators. In that way, we propose the frequency at maximum power as a proper seismic index since it is directly related with the intrinsic temperature, mass and radius of the star. This parameter seems not to be affected by rotation, inclination, extinction or resonances, with the exception of the evolution of the stellar parameters. Furthermore, we can constrain rotation and inclination using the departure of temperature produced by the gravity-darkening effect. This is especially feasible for fast rotators as most of delta Scuti stars seem to be.
- ID:
- ivo://CDS.VizieR/J/AJ/158/141
- Title:
- Differential photometry & RVs of HAT-P-69 & HAT-P-70
- Short Name:
- J/AJ/158/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Wide-field surveys for transiting planets are well suited to searching diverse stellar populations, enabling a better understanding of the link between the properties of planets and their parent stars. We report the discovery of HAT-P-69 b (TOI 625.01) and HAT-P-70 b (TOI 624.01), two new hot Jupiters around A stars from the Hungarian-made Automated Telescope Network (HATNet) survey that have also been observed by the Transiting Exoplanet Survey Satellite. HAT-P-69 b has a mass of 3.58_-0.58_^+0.58^ M_Jup_ and a radius of 1.676_-0.033_^+0.051^ R_Jup_ and resides in a prograde 4.79 day orbit. HAT-P-70 b has a radius of 1.87_-0.10_^+0.15^ R_Jup_ and a mass constraint of <6.78 (3{sigma}) M_Jup_ and resides in a retrograde 2.74 day orbit. We use the confirmation of these planets around relatively massive stars as an opportunity to explore the occurrence rate of hot Jupiters as a function of stellar mass. We define a sample of 47126 main-sequence stars brighter than T_mag_=10 that yields 31 giant planet candidates, including 18 confirmed planets, 3 candidates, and 10 false positives. We find a net hot Jupiter occurrence rate of 0.41+/-0.10% within this sample, consistent with the rate measured by Kepler for FGK stars. When divided into stellar mass bins, we find the occurrence rate to be 0.71+/-0.31% for G stars, 0.43+/-0.15% for F stars, and 0.26+/-0.11% for A stars. Thus, at this point, we cannot discern any statistically significant trend in the occurrence of hot Jupiters with stellar mass.
- ID:
- ivo://CDS.VizieR/J/ApJ/771/110
- Title:
- Early-type stars in Taurus-Auriga
- Short Name:
- J/ApJ/771/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the results of a search for early-type stars associated with the Taurus-Auriga molecular cloud complex, a diffuse nearby star-forming region noted as lacking young stars of intermediate and high mass. We investigate several sets of possible O, B, and early A spectral class members. The first is a group of stars for which mid-infrared images show bright nebulae, all of which can be associated with stars of spectral-type B. The second group consists of early-type stars compiled from (1) literature listings in SIMBAD, (2) B stars with infrared excesses selected from the Spitzer Space Telescope survey of the Taurus cloud (Rebull et al. 2010, J/ApJS/186/259), (3) magnitude- and color-selected point sources from the Two Micron All Sky Survey (Skrutskie et al. 2006, VII/233), and (4) spectroscopically identified early-type stars from the Sloan Digital Sky Survey coverage of the Taurus region (Finkbeiner et al. 2004AJ....128.2577F; Knapp et al. 2007AAS...211.2907K). We evaluated stars for membership in the Taurus-Auriga star formation region based on criteria involving: spectroscopic and parallactic distances, proper motions and radial velocities, and infrared excesses or line emission indicative of stellar youth. For selected objects, we also model the scattered and emitted radiation from reflection nebulosity and compare the results with the observed spectral energy distributions to further test the plausibility of physical association of the B stars with the Taurus cloud. This investigation newly identifies as probable Taurus members three B-type stars: HR 1445 (HD 28929), {tau} Tau (HD 29763), 72 Tau (HD 28149), and two A-type stars: HD 31305 and HD 26212, thus doubling the number of stars A5 or earlier associated with the Taurus clouds. Several additional early-type sources including HD 29659 and HD 283815 meet some, but not all, of the membership criteria and therefore are plausible, though not secure, members.
- ID:
- ivo://CDS.VizieR/J/MNRAS/439/2078
- Title:
- High-frequency A-type pulsators
- Short Name:
- J/MNRAS/439/2078
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a survey using the WASP archive to search for high-frequency pulsations in F-, A- and B-type stars. Over 1.5 million targets have been searched for pulsations with amplitudes greater than 0.5 millimagnitude. We identify over 350 stars which pulsate with periods less than 30min. Spectroscopic follow-up of selected targets has enabled us to confirm 10 new rapidly oscillating Ap stars, 13 pulsating Am stars and the fastest known {delta} Scuti star. We also observe stars which show pulsations in both the high-frequency domain and the low-frequency {delta} Scuti range. This work shows the power of the WASP photometric survey to find variable stars with amplitudes well below the nominal photometric precision per observation.
- ID:
- ivo://CDS.VizieR/J/ApJS/168/277
- Title:
- HK-Survey field horizontal-branch candidates
- Short Name:
- J/ApJS/168/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present coordinates and available photometric information (either from previous or recent broadband UBV observations, and near-infrared photometry from the 2MASS Point Source Catalog) for 12,056 stars (11,516 of which are unique) identified in the HK Survey of Beers and colleagues as candidate field horizontal-branch or A-type stars. These stars, in the apparent magnitude range 10<=B<=16.0, were selected using an objective-prism/interference-filter survey technique. The availability of 2MASS information permits assembly of a cleaned version of this catalog, comprising likely blue horizontal-branch (BHB) stars or blue stragglers in the color interval [-0.2<=(B-V)_0_<=+0.2].
- ID:
- ivo://CDS.VizieR/J/ApJS/103/433
- Title:
- Horizontal-branch and A-type star catalog. II
- Short Name:
- J/ApJS/103/433
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present coordinates and brightness estimates for 4175 candidate field horizontal-branch and A-type stars, in the magnitude range 10<=B<=15.5, selected using an objective-prism/interference-filter survey technique. The candidates lie primarily in the northern Galactic hemisphere and complement a previously published sample of southern Galactic hemisphere candidates. Available spectroscopy and photometry indicates that the great majority of the candidates are likely to be bona fide members of either the field blue horizontal- branch population or the blue, metal-deficient, high surface gravity stars referred to by Preston, Beers, & Schectman (1994AJ....108..538P) as BMP stars. The remaining stars in the catalog are likely to be a mix of metal-deficient turnoff stars, metallic-line (Am) stars, field red horizontal-branch stars, optical doubles with overlapping objective-prism spectra, and (particularly among the fainter candidates) inadvertently included late-type stars.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A142
- Title:
- HR4796 debris disk Qphi and Uphi images
- Short Name:
- J/A+A/630/A142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Debris disks are the natural by-products of the planet formation process. Scatte red or polarized light observations are mostly sensitive to small dust grains that are released from the grinding down of bigger planetesimals. High angular resolution observations at optical wavelengths can provide key constraints on the radial and azimuthal distribution of the small dust grains. These constraints can help us better understand where most of the dust grains are released upon collisions. We present SPHERE/ZIMPOL observations of the debris disk around HR 4796A, and model the radial profiles along several azimuthal angles of the disk with a code that accounts for the effect of stellar radiation pressure. This enables us to derive an appropriate description for the radial and azimuthal distribution of the small dust grains. Even though we only model the radial profiles along (or close to) the semi-major axis of the disk, our best-fit model is not only in good agreement with our observations but also with previously published datasets (from near-IR to sub-mm wavelengths). We find that the reference radius is located at 76.4+/-0.4au, and the disk has an eccentricity of 0.076_-0.010_^+0.016^, with the pericenter located on the front side of the disk (north of the star). We find that small dust grains must be preferentially released near the pericenter to explain the observed brightness asymmetry. Even though parent bodies spend more time near the apocenter, the brightness asymmetry implies that collisions happen more frequently near the pericenter of the disk. Our model can successfully reproduce the shape of the outer edge of the disk, without having to invoke an outer planet shepherding the debris disk. With a simple treatment of the effect of the radiation pressure, we conclude that the parent planetesimals are located in a narrow ring of about 3.6au in width.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/1970
- Title:
- Kepler {delta} Sct stars amplitude modulation
- Short Name:
- J/MNRAS/460/1970
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a thorough search for amplitude modulation of pulsation modes in 983 {delta} Sct stars, which have effective temperatures between 6400<T_eff_<10000K in the Kepler Input Catalogue and were continuously observed by the Kepler Space Telescope for 4yr. We demonstrate the diversity in pulsational behaviour observed, in particular non-linearity, which is predicted for {delta} Sct stars. We analyse and discuss examples of {delta} Sct stars with constant amplitudes and phases; those that exhibit amplitude modulation caused by beating of close-frequency pulsation modes; those that exhibit pure amplitude modulation (with no associated phase variation); those that exhibit phase modulation caused by binarity; and those that exhibit amplitude modulation caused by non-linearity. Using models and examples of individual stars, we demonstrate that observations of the changes in amplitude and phase of pulsation modes can be used to distinguish among the different scenarios. We find that 603 {delta} Sct stars (61.3 per cent) exhibit at least one pulsation mode that varies significantly in amplitude over 4yr. Conversely, many {delta} Sct stars have constant pulsation amplitudes so short-length observations can be used to determine precise frequencies, amplitudes and phases for the most coherent and periodic {delta} Sct stars. It is shown that amplitude modulation is not restricted to a small region on the HR diagram, therefore not necessarily dependent on stellar parameters such as T_eff_, logg or [Fe/H]. Our catalogue of 983 {delta} Sct stars will be useful for comparisons to similar stars observed by K2 and TESS, because the length of the 4-yr Kepler data set will not be surpassed for some time.
- ID:
- ivo://CDS.VizieR/II/42
- Title:
- K-Line Photometry of A Stars
- Short Name:
- II/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A narrow-band spectrometer, compensated for seeing and transparency variations, has been constructed and used to measure the strength of the calcium K-line (3933.68{AA}) in 146 A-type stars. The observations were made in the spring of 1966 with the No.4 16-inch (40cm) telescope at Kitt Peak National Observatory.
