- ID:
- ivo://CDS.VizieR/J/A+A/304/406
- Title:
- Photometry and radial velocities of 16 Lac
- Short Name:
- J/A+A/304/406
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric and spectroscopic observations of the {beta} Cephei star 16 Lacertae obtained in 1983 and 1984 are presented and analysed. Using all the published maxima we have computed ephemerides for each of the three pulsational modes. No period variation is detected from 1950 to 1983. In order to identify the pulsational modes corresponding to the three main periods of 16 Lac we have applied different methods based on photometric and radial velocity variations. All give the same results: the mode corresponding to the largest amplitude P_1_ (016917d) is radial, P_2_ (017079d) is a nonradial mode of degree l=2. For P_3_ (018171d) the results are more dubious, but P_3_ is probably a l=1 nonradial mode. We have also studied the interaction between pulsation and binarity in 16 Lac. We confirm the existence of a resonance phenomenon between the radial and nonradial modes: the ratios between the beat frequencies of the pulsational modes and the orbital frequency are close but significantly different from simple rational numbers. According to Kato (1974) that means that the nonradial modes might be excited or at least enhanced by tidal effects. They would have been selected among all the possible modes because their ability to be resonant with the radial mode. The photometric amplitude of P_3_ in both filters appears to be variable from night to night in correlation with the orbital phase but despite its rapid and irregular fluctuations, the P_3_ amplitude stayed in constant average over 80 years. The present observations confirm the decrease of P_1_ and P_2_ amplitudes since 1950 but an analysis of older radial velocity data shows that the amplitude of the P_1_ mode went through a maximum around the middle of the century before the observed decrease of the last thirty years.
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- ID:
- ivo://CDS.VizieR/J/AJ/150/31
- Title:
- Photometry and redshifts of galaxies in the UDF
- Short Name:
- J/AJ/150/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry and derived redshifts from up to eleven bandpasses for 9927 galaxies in the Hubble Ultra Deep field (UDF), covering an observed wavelength range from the near-ultraviolet (NUV) to the near-infrared (NIR) with Hubble Space Telescope observations. Our Wide Field Camera 3 (WFC3)/UV F225W, F275W, and F336W image mosaics from the ultra-violet UDF (UVUDF) imaging campaign are newly calibrated to correct for charge transfer inefficiency, and use new dark calibrations to minimize background gradients and pattern noise. Our NIR WFC3/IR image mosaics combine the imaging from the UDF09 and UDF12 campaigns with CANDELS data to provide NIR coverage for the entire UDF field of view. We use aperture-matched point-spread function corrected photometry to measure photometric redshifts in the UDF, sampling both the Lyman break and Balmer break of galaxies at z~0.8--3.4, and one of the breaks over the rest of the redshift range. Our comparison of these results with a compilation of robust spectroscopic redshifts shows an improvement in the galaxy photometric redshifts by a factor of two in scatter and a factor three in outlier fraction (OLF) over previous UDF catalogs. The inclusion of the new NUV data is responsible for a factor of two decrease in the OLF compared to redshifts determined from only the optical and NIR data, and improves the scatter at z<0.5 and at z>2. The panchromatic coverage of the UDF from the NUV through the NIR yields robust photometric redshifts of the UDF, with the lowest OLF available.
- ID:
- ivo://CDS.VizieR/J/AJ/160/192
- Title:
- Photometry and RVs of K2-25b with HPF
- Short Name:
- J/AJ/160/192
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using radial velocity data from the Habitable Zone Planet Finder, we have measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity of its M4.5 dwarf host star in the 600-800Myr Hyades cluster. This is one of the youngest planetary systems for which both of these quantities have been measured and one of the very few M dwarfs with a measured obliquity. Based on a joint analysis of the radial velocity data, time-series photometry from the K2 mission, and new transit light curves obtained with diffuser-assisted photometry, the planet's radius and mass are 3.44{+/-}0.12R_{Earth}_ and 24.5_-5.2_^+5.7^M_{Earth}_. These properties are compatible with a rocky core enshrouded by a thin hydrogen-helium atmosphere (5% by mass). We measure an orbital eccentricity of e=0.43{+/-}0.05. The sky-projected stellar obliquity is {lambda}=3{deg}{+/-}16{deg}, compatible with spin- orbit alignment, in contrast to other "hot Neptunes" that have been studied around older stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/854/L14
- Title:
- Photometry and spectra of SN 2017dio
- Short Name:
- J/ApJ/854/L14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- SN 2017dio shows both spectral characteristics of a type-Ic supernova (SN) and signs of a hydrogen-rich circumstellar medium (CSM). Prominent, narrow emission lines of H and He are superposed on the continuum. Subsequent evolution revealed that the SN ejecta are interacting with the CSM. The initial SN Ic identification was confirmed by removing the CSM interaction component from the spectrum and comparing with known SNe Ic, and reversely, adding a CSM interaction component to the spectra of known SNe Ic and comparing them to SN 2017dio. Excellent agreement was obtained with both procedures, reinforcing the SN Ic classification. The light curve constrains the pre-interaction SN Ic peak absolute magnitude to be around Mg=-17.6mag. No evidence of significant extinction is found, ruling out a brighter luminosity required by a SN Ia classification. These pieces of evidence support the view that SN 2017dio is a SN Ic, and therefore the first firm case of a SN Ic with signatures of hydrogen-rich CSM in the early spectrum. The CSM is unlikely to have been shaped by steady-state stellar winds. The mass loss of the progenitor star must have been intense, dM/dt~0.02({epsilon}_Ha_/0.01)^-1^*(v_wind_/500km/s)* (v_shock_/10000km/s)^-3^M_{sun}_/yr, peaking at a few decades before the SN. Such a high mass loss rate might have been experienced by the progenitor through eruptions or binary stripping.
- ID:
- ivo://CDS.VizieR/V/125
- Title:
- Photometry and Spectroscopy for Luminous Stars
- Short Name:
- V/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- of the paper: The birthrate of stars of masses >=10M_{sun}_ is estimated from a sample of just over 400 O3-B2 dwarfs within 1.5kpc of the Sun and the result extrapolated to estimate the Galactic supernova rate contributed by such stars. The solar-neighborhood Galactic-plane massive star birthrate is estimated at ~176stars/kpc^3^/Myr. On the basis of a model in which the Galactic stellar density distribution comprises a "disk+central hole" like that of the dust infrared emission (as proposed by Drimmel and Spergel), the Galactic supernova rate is estimated at probably not less than ~1 nor more than ~2 per century and the number of O3-B2 dwarfs within the solar circle at ~200000.
- ID:
- ivo://CDS.VizieR/J/A+AS/95/87
- Title:
- Photometry and Spectroscopy in A2218
- Short Name:
- J/A+AS/95/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new photometric and spectroscopic observations of objects in the field of the cluster of galaxies Abell 2218. The photometric survey, centered on the cluster core, extends to a field of about 4'x4'. It was performed in 5 bands (B, g, r, i and z filters). This sample, which includes 729 objects, is about three times larger than the survey made by Butcher and collaborator (Butcher et al., 1983ApJS...52..183B, Butcher & Oemler, 1984ApJ...285..426B) in the same central region of the field. Only 228 objects appear in both catalogues since our survey covers a smaller region.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/1484
- Title:
- Photometry and spectroscopy in IC 2391
- Short Name:
- J/ApJ/706/1484
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the stellar and substellar mass function (MF) of the open cluster IC 2391, plus its radial dependence, and use this to put constraints on the formation mechanism of brown dwarfs (BDs). Our multi-band optical and infrared photometric survey with spectroscopic follow-up covers 11deg^2^, making it the largest survey of this cluster to date. From our preliminary spectroscopic follow-up, to confirm BD status and cluster membership, we find that all candidates are M dwarfs (in either the field or the cluster), demonstrating the efficiency of our photometric selection method in avoiding contaminants (e.g., red giants). About half of our photometric candidates for which we have spectra are spectroscopically confirmed as cluster members; two are new spectroscopically confirmed BD members of IC 2391.
- ID:
- ivo://CDS.VizieR/J/AJ/131/2383
- Title:
- Photometry and spectroscopy in the HDF-S
- Short Name:
- J/AJ/131/2383
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a deep photometric (B- and R-band) catalog and an associated spectroscopic redshift survey conducted in the vicinity of the Hubble Deep Field-South. The spectroscopy yields 53 extragalactic redshifts in the range 0<z<1.4, substantially increasing the body of spectroscopic work in this field to over 200 objects. The targets are selected from deep Anglo-Australian Telescope prime-focus images complete to R<24, and the spectroscopy is 50% complete at R=23.
- ID:
- ivo://CDS.VizieR/J/AJ/147/36
- Title:
- Photometry and spectroscopy of AQ Ser
- Short Name:
- J/AJ/147/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report differential photometric observations and radial-velocity measurements of the detached, 1.69 day period, double-lined eclipsing binary AQ Ser. Accurate masses and radii for the components are determined to better than 1.8% and 1.1%, respectively, and are M_1_=1.417+/-0.021M_{sun}_, M_2_=1.346+/-0.024M_{sun}_, R_1_=2.451+/-0.027R_{sun}_, and R_2_=2.281+/-0.014R_{sun}_. The temperatures are 6340+/-100K (spectral type F6) and 6430+/-100K (F5), respectively. Both stars are considerably evolved, such that predictions from stellar evolution theory are particularly sensitive to the degree of extra mixing above the convective core (overshoot). The component masses are different enough to exclude a location in the H-R diagram past the point of central hydrogen exhaustion, which implies the need for extra mixing. Moreover, we find that current main-sequence models are unable to match the observed properties at a single age even when allowing the unknown metallicity, mixing length parameter, and convective overshooting parameter to vary freely and independently for the two components. The age of the more massive star appears systematically younger. AQ Ser and other similarly evolved eclipsing binaries showing the same discrepancy highlight an outstanding and largely overlooked problem with the description of overshooting in current stellar theory.
- ID:
- ivo://CDS.VizieR/J/AJ/135/564
- Title:
- Photometry and spectroscopy of BHB candidates
- Short Name:
- J/AJ/135/564
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a complete spectroscopic survey of 2414 2MASS-selected blue horizontal branch (BHB) candidates selected over 4300{deg}^2^ of the sky. We identify 655 BHB stars in this non-kinematically selected sample. We calculate the luminosity function of field BHB stars, and find evidence for very few hot BHB stars in the field.
