- ID:
- ivo://CDS.VizieR/J/A+AS/136/515
- Title:
- DQ Cephei amplitude variations
- Short Name:
- J/A+AS/136/515
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A period analysis of the data obtained in six nights of differential photoelectric photometry of the {delta} Scuti star DQ Cephei (about 42 hours) confirms the pulsation modes of f_1_=8.0480 cycle per day and f_2_=12.6826 cycle per day. The result adjusts well to the observations that cover a time span of 46 years. Comparing with the results obtained for different years, we discovered obvious amplitude variations of the two modes. These amplitude variations show phase differences of almost 180 degrees. The variation period probably is longer than 46 years.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/612/447
- Title:
- Draco 119 and HD 88609 equivalent widths
- Short Name:
- J/ApJ/612/447
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the abundance analysis of new high signal-to-noise ratio (S/N) spectra of the most metal-poor ([Fe/H]=-2.95) star currently known to be a member of a dwarf galaxy, the Draco dSph red giant D119. No absorption lines for elements heavier than Ni are detected in two Keck HIRES spectra covering the 3850-6655{AA} wavelength range, a phenomenon not previously noted in any other metal-poor star. We present upper limits for several heavy-element abundances. The most stringent limits, based on the nondetection of SrII and BaII lines, indicate that the total s- and r-process enrichment of D119 is at least 100times smaller than Galactic stars of similar metallicity. The light-element abundances are consistent with the star having formed out of material enriched primarily by massive Type II supernovae (M>20-25M_{Sun}_). If this is the case, we are forced to conclude that massive, metal-poor Type II supernovae did not contribute to the r-process in the proto-Draco environment. We compare the abundance pattern observed in D119 to current predictions of prompt enrichment and pair-instability supernovae and find that the model predictions fail by an order of magnitude or more for many elements.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/L59
- Title:
- Draco II stars gi magnitude & radial velocities
- Short Name:
- J/MNRAS/458/L59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first spectroscopic analysis of the faint and compact stellar system Draco II (Dra II, M_V_=-2.9+/-0.8,r_h_=19^+8^_-6_pc), recently discovered in the Panoramic Survey Telescope and Rapid Response System 1 3{PI} survey. The observations, conducted with DEIMOS on the Keck II telescope, establish some of its basic characteristics: the velocity data reveal a narrow peak with nine member stars at a systemic heliocentric velocity <v_r_>=-347.6^+1.7^_-1.8_km/s, thereby confirming Dra II is a satellite of the Milky Way; we infer a velocity dispersion with {sigma}_vr_=2.9+/-2.1km/s (<8.4km/s at the 95 per cent confidence level), which implie log_10_(M_1/2_)-5.5^+0.4^_-0.6_ and log_10_((M/L_)1/2_)=2.7^+0.5^_-0.8_, in Solar units; furthermore, very weak calcium triplet lines in the spectra of the high signal-to-noise member stars imply [Fe/H]<-2.1, whilst variations in the line strengths of two stars with similar colours and magnitudes suggest a metallicity spread in Dra II. These new data cannot clearly discriminate whether Draco II is a star cluster or amongst the faintest, most compact, and closest dwarf galaxies. However, the sum of the three - individually inconclusive - pieces of evidence presented here seems to favour the dwarf galaxy interpretation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/375/831
- Title:
- Draco MegaCam, INT and HST photometry
- Short Name:
- J/MNRAS/375/831
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Draco dwarf spheroidal galaxy (dSph), with its apparent immense mass-to-light ratio and compact size, holds many clues to the nature of the enigmatic dark matter. Here we present deep photometric studies of this dwarf galaxy, undertaken with the MegaCam Camera at the Canada-France-Hawaii Telescope, the Wide Field Camera at the Isaac Newton Telescope and the Wide Field and Planetary Camera onboard the Hubble Space Telescope (HST). The new photometric data cover the entirety of the galaxy, and reach i'=24.5 at 50 per cent completeness, significantly deeper than previous panoramic studies, allowing searches for tidal disturbances of much lower surface brightness than has been possible before. With these improved statistics, we find no evidence for asymmetric disturbances or tidal tails that possess more than 3 per cent of the stars found within the centre of the galaxy. We find that the central stellar density, as probed by the HST data, rises into the central 0.5arcmin. Uncertainties in the position of the centroid of the galaxy do not allow us to determine whether the apparent flattening of the profile interior to 0.5arcmin is reliable or not. Draco is therefore a flawless dwarf galaxy, featureless and apparently unaffected by Galactic tides.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A109
- Title:
- Draco nebula Herschel 250um map
- Short Name:
- J/A+A/599/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Draco nebula is a high Galactic latitude interstellar cloud observed at velocities corresponding to the intermediate velocity cloud regime. This nebula shows unusually strong CO emission and remarkably high-contrast small-scale structures for such a diffuse high Galactic latitude cloud. The 21cm emission of the Draco nebula reveals that it is likely to have been formed by the collision of a cloud entering the disk of the Milky Way. Such physical conditions are ideal to study the formation of cold and dense gas in colliding flows of diffuse and warm gas. The objective of this study is to better understand the process of structure formation in a colliding flow and to describe the ects of matter entering the disk on the interstellar medium. We conducted Herschel-SPIRE observations of the Draco nebula. The clumpfind algorithm was used to identify and characterize the small-scale structures of the cloud.
4656. Draft EIS Colour Catalog
- ID:
- ivo://CDS.VizieR/II/234
- Title:
- Draft EIS Colour Catalog
- Short Name:
- II/234
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is a DRAFT multicolour catalogue resulting from the multi- passband ESO Imaging Survey (EIS, see J/A+A/379/740) in the direction of the Chandra Deep Field South (CDF-S), located at RA=03h32m, Dec=-27{deg}48'. The observations were conducted at the ESO/MPG 2.2 m telescope at La Silla using the 8kx8k Wide-Field Imager (WFI).
4657. DRaGONS survey
- ID:
- ivo://CDS.VizieR/J/ApJ/649/63
- Title:
- DRaGONS survey
- Short Name:
- J/ApJ/649/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from the Distant Radio Galaxies Optically Non-detected in the SDSS (DRaGONS) survey. Using a novel selection technique for identifying high-redshift radio galaxy (HzRG) candidates, a large sample is compiled using bright (S_1.4GHz_>100mJy) radio sources from the FIRST survey having no optical counterpart in the SDSS. Near-IR K-band imaging for 96 targets allows preliminary identification of HzRG candidates through the well-known K-z relation, for subsequent spectroscopic observation. We measure magnitudes brighter than K~19.5 for 70 of the 96, and limiting magnitudes for the remainder. Redshifts based on a linear fit to the K-z diagram give a mean <z>=2.5 and median z=2.0, showing that this method should be efficient at identifying a large number of HzRGs.
4658. DRAO ELAIS N1 catalog
- ID:
- ivo://CDS.VizieR/J/ApJ/714/1689
- Title:
- DRAO ELAIS N1 catalog
- Short Name:
- J/ApJ/714/1689
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of deep polarization imaging at 1.4GHz with the Dominion Radio Astrophysical Observatory as part of the DRAO Planck Deep Fields project. This deep extragalactic field covers 15.16deg^2^ centered at RA(J2000)=16:14 and DE(J2000)=54:56, has an angular resolution of 42"x62" at the field center, and reaches a sensitivity of 55uJy/beam in Stokes I and 45uJy/beam in Stokes Q and U. We detect 958 radio sources in Stokes I of which 136 are detected in polarization. We present the Euclidean-normalized polarized differential source counts down to 400uJy. These counts indicate that sources have a higher degree of fractional polarization at fainter Stokes I flux density levels than for brighter sources, confirming an earlier result. We find that the majority of our polarized sources are steep-spectrum objects with a mean spectral index of -0.77, and there is no correlation between fractional polarization and spectral index. We also matched deep field sources to counterparts in the Faint Images of the Radio Sky at Twenty Centimeters catalog. Of the polarized sources, 77% show structure at the arcsecond scale whereas only 38% of the sources with no detectable polarization show such structure. The median fractional polarization for resolved sources is 6.8%, while it is 4.4% for compact objects. The polarized radio sources in our deep field are predominantly those sources which are resolved and show the highest degrees of fractional polarization, indicating that the lobe dominated structure may be the source of the highly polarized sources. These resolved radio galaxies dominate the polarized source counts at P_0_=(Q^2^+U^2^)^0.5^<3mJy.
- ID:
- ivo://CDS.VizieR/VIII/55
- Title:
- DRAO Penticton P-survey Database
- Short Name:
- VIII/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains 1692 radio sources observed with the Penticton synthesis telescope at 408 MHz and at 1420 MHz. The catalog is comprised of sources detected in the P-surveys 1P through 9P, 12P through 15P, and 20P through 27P (see the "References" section below). The database was provided by R.Roger & C.R.Purton in May 1990 and an update of the data with further P-surveys is currently in progress.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/1561
- Title:
- DR 21 Chandra source catalogue
- Short Name:
- J/MNRAS/437/1561
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have studied the young low-mass pre-main sequence (PMS) stellar population associated with the massive star-forming region DR 21 by using archival X-ray Chandra observations and by complementing them with existing optical and infrared (IR) surveys. The Chandra observations have revealed for the first time a new highly extincted population of PMS low-mass stars previously missed in observations at other wavelengths. The X-ray population exhibits three main stellar density peaks, coincident with the massive star-forming regions, being the DR 21 core the main peak. The cross-correlated X-ray/IR sample exhibits a radial 'Spokes-like' stellar filamentary structure that extends from the DR 21 core towards the northeast. The near-IR data reveal a centrally peaked structure for the extinction, which exhibits its maximum in the DR 21 core and gradually decreases with the distance to the N-S cloud axis and to the cluster centre. We find evidence of a global mass segregation in the full low-mass stellar cluster, and of a stellar age segregation, with the youngest stars still embedded in the N-S cloud, and more evolved stars more spatially distributed. The results are consistent with the scenario where an elongated overall potential well created by the full low-mass stellar cluster funnels gas through filaments feeding stellar formation. Besides the full gravitational well, smaller scale local potential wells created by dense stellar sub-clusters of low-mass stars are privileged in the competition for the gas of the common reservoir, allowing the formation of massive stars. We also discuss the possibility that a stellar collision in the very dense stellar cluster revealed by Chandra in the DR 21 core is the origin of the large-scale and highly energetic outflow arising from this region.