- ID:
- ivo://CDS.VizieR/J/ApJS/105/343
- Title:
- Universidad Complutense de Madrid list 2
- Short Name:
- J/ApJS/105/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A low dispersion objective-prism survey for low-redshift emission-line galaxies (ELGs) is being carried out by the University Complutense de Madrid with the Schmidt telescope at the German-Spanish Observatory of Calar Alto (Almeria, Spain). A 4{deg} full aperture prism, which provides a dispersion of 1950{AA}/mm, and IIIa-F emulsion combination has been used to search for ELGs selected by the presence of H{alpha} emission in their spectra. A compilation of descriptions and positions, along with finding charts, is presented for 103 emission-line objects. This is the second list, which contains objects located in a region of the sky covering 201.4{deg}^2^ in seven fields near {alpha}=15h and {delta}=25{deg}.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/122/415
- Title:
- Universidad Complutense de Madrid list 3
- Short Name:
- J/ApJS/122/415
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new low-dispersion objective-prism search for low-redshift (z<0.045) emission-line galaxies (ELGs) has been carried out by the Universidad Complutense de Madrid using the Schmidt Telescope at the Calar-Alto Observatory. This is a continuation of the UCM Survey, which was performed by visual selection of candidates in photographic plates via the presence of the H{alpha}+[N II]{lambda}6584 blend in emission. In making this new list we have applied an automatic procedure, fully developed by us, for selecting and analyzing ELG candidates on the digitized images obtained with the "Machine Automatique a Mesurer pour l'Astronomie" (MAMA). The analyzed region of the sky covers 189deg^2^ in nine fields near RA=14h and 17h, DE=25{deg}. The final sample contains 113 candidates. Special effort has been made to obtain a large amount of information directly from our uncalibrated plates by using several external calibrations. The parameters obtained for the ELG candidates allow us to study the statistical properties of the sample.
- ID:
- ivo://CDS.VizieR/J/ApJS/95/387
- Title:
- Universidad Complutense de Madrid list 1
- Short Name:
- J/ApJS/95/387
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A low dispersion objective-prism survey for low-redshift emission-line galaxies (ELGs) is being carried out by the University Complutense de Madrid with the Schmidt telescope at the German-Spanish Observatory of Calar Alto (Almeria, Spain). A 4deg full aperture prism, which provides a dispersion of 1950A/mm, and IIIa-F emulsion combination has been used to search for ELGs selected by the presence of H{alpha} emission in their spectra. Our survey has proved to be able to recover objects already found by similar surveys with different techniques and, what is more important, to discover new objects not previously catalogued. A compilation of descriptions and positions, along with finding charts when necessary, is presented for 160 extragalactic emission-line objects. This is the first list, which contains objects located in a region of the sky covering 270deg^2^ in 10 fields near {alpha}=0h and {delta}=20deg.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A195
- Title:
- Unknown active galactic nuclei study
- Short Name:
- J/A+A/647/A195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We collect data at all frequencies for the new sources classified as unknown active galactic nuclei (AGNs) in the latest Burst Alert Telescope all-sky hard X-ray catalog. Focusing on the 36 sources with measured redshift, we compute their spectral energy distribution (SED) from radio to {gamma}-rays with the aim to classify these objects. We apply emission models that attempt to reproduce the obtained SEDs, including: (i) a standard thin accretion disk together with an obscuring torus and a X-ray corona; (ii) a two temperature thick advection-dominated flow; (iii) an obscured AGN model, accounting for absorption along the line of sight at kiloelectronvolt energies and in the optical band; and (iv) a phenomenological model to describe the jet emission in blazar-like objects. We integrate the models with the SWIRE template libraries to account for the emission of the host galaxy. For every source we found a good agreement between data and our model. Considering that the sources were selected in the hard X-ray band, which is rather unaffected by absorption, we expected and found a large fraction of absorbed radio-quiet AGNs (31 out of 36) and some additional rare radio-loud sources (5 out of 36), since the jet emission in hard X-rays is important for aligned jets owing to the boost produced by the beaming effect. With our work we can confirm the hypothesis that a number of galaxies, whose optical spectra lack AGN emission features, host an obscured active nucleus. The approach we used proved to be efficient in rapidly identifying objects, which commonly used methods were not able to classify.
- ID:
- ivo://CDS.VizieR/J/ApJ/856/85
- Title:
- Unlocking CO depletion in protoplanetary disks. I.
- Short Name:
- J/ApJ/856/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CO is commonly used as a tracer of the total gas mass in both the interstellar medium and in protoplanetary disks. Recently, there has been much debate about the utility of CO as a mass tracer in disks. Observations of CO in protoplanetary disks reveal a range of CO abundances, with measurements of low CO to dust mass ratios in numerous systems. One possibility is that carbon is removed from CO via chemistry. However, the full range of physical conditions conducive to this chemical reprocessing is not well understood. We perform a systematic survey of the time dependent chemistry in protoplanetary disks for 198 models with a range of physical conditions. We vary dust grain size distribution, temperature, comic-ray and X-ray ionization rates, disk mass, and initial water abundance, detailing what physical conditions are necessary to activate the various CO depletion mechanisms in the warm molecular layer. We focus our analysis on the warm molecular layer in two regions: the outer disk (100au) well outside the CO snowline and the inner disk (19au) just inside the midplane CO snowline. After 1Myr, we find that the majority of models have a CO abundance relative to H_2_ less than 10^-4^ in the outer disk, while an abundance less than 10^-5^ requires the presence of cosmic-rays. Inside the CO snowline, significant depletion of CO only occurs in models with a high cosmic-ray rate. If cosmic-rays are not present in young disks, it is difficult to chemically remove carbon from CO. Additionally, removing water prior to CO depletion impedes the chemical processing of CO. Chemical processing alone cannot explain current observations of low CO abundances. Other mechanisms must also be involved.
- ID:
- ivo://CDS.VizieR/J/AJ/157/211
- Title:
- Unresolved binaries in TESS with speckle imaging
- Short Name:
- J/AJ/157/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) is conducting a two-year wide-field survey searching for transiting exoplanets around nearby bright stars that will be ideal for follow-up characterization. To facilitate studies of planet compositions and atmospheric properties, accurate and precise planetary radii need to be derived from the transit light curves. Since 40%-50% of exoplanet host stars are in multiple star systems, however, the observed transit depth may be diluted by the flux of a companion star, causing the radius of the planet to be underestimated. High angular resolution imaging can detect companion stars that are not resolved in the TESS Input Catalog, or by seeing-limited photometry, to validate exoplanet candidates and derive accurate planetary radii. We examine the population of stellar companions that will be detectable around TESS planet candidate host stars, and those that will remain undetected, by applying the detection limits of speckle imaging to the simulated host star populations of Sullivan et al. (2015, J/ApJ/809/77) and Barclay et al. (2018, J/ApJS/239/2). By detecting companions with contrasts of {Delta}m~<7-9 and separations of ~0.02"-1.2", speckle imaging can detect companion stars as faint as early M stars around A-F stars and stars as faint as mid-M around G-M stars, as well as up to 99% of the expected binary star distribution for systems located within a few hundred parsecs.
- ID:
- ivo://CDS.VizieR/J/AJ/129/927
- Title:
- Unresolved H{alpha} enhancements in WHAM survey
- Short Name:
- J/AJ/129/927
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified 85 regions of enhanced H{alpha} emission at |b|>10{deg} subtending approximately 1{deg} or less on the Wisconsin H{alpha} Mapper (WHAM) sky survey (Cat. II/249). These high-latitude "WHAM point sources" have H{alpha} fluxes of 10^-11^-10^-9^ergs/cm^2^/s, radial velocities within about 70km/s of the LSR, and line widths that range from less than 20 to about 80km/s (FWHM). Twenty-nine of these enhancements are not identified with either cataloged nebulae or hot stars and appear to have kinematic properties that differ from those observed for planetary nebulae. Another 14 enhancements are near hot evolved low-mass stars that had no previously reported detections of associated nebulosity. The remainder of the enhancements are cataloged planetary nebulae and small, high-latitude HII regions surrounding massive O and early B stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/828/111
- Title:
- Unsupervised clustering of type II SNe LCs
- Short Name:
- J/ApJ/828/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As new facilities come online, the astronomical community will be provided with extremely large data sets of well-sampled light curves (LCs) of transients. This motivates systematic studies of the LCs of supernovae (SNe) of all types, including the early rising phase. We performed unsupervised k-means clustering on a sample of 59 R-band SNII LCs and find that the rise to peak plays an important role in classifying LCs. Our sample can be divided into three classes: slowly rising (II-S), fast rise/slow decline (II-FS), and fast rise/fast decline (II-FF). We also identify three outliers based on the algorithm. The II-FF and II-FS classes are disjoint in their decline rates, while the II-S class is intermediate and "bridges the gap." This may explain recent conflicting results regarding II-P/II-L populations. The II-FS class is also significantly less luminous than the other two classes. Performing clustering on the first two principal component analysis components gives equivalent results to using the full LC morphologies. This indicates that Type II LCs could possibly be reduced to two parameters. We present several important caveats to the technique, and find that the division into these classes is not fully robust. Moreover, these classes have some overlap, and are defined in the R band only. It is currently unclear if they represent distinct physical classes, and more data is needed to study these issues. However, we show that the outliers are actually composed of slowly evolving SN IIb, demonstrating the potential of such methods. The slowly evolving SNe IIb may arise from single massive progenitors.
- ID:
- ivo://CDS.VizieR/J/MNRAS/385/1749
- Title:
- UNSW catalog of Variable Stars
- Short Name:
- J/MNRAS/385/1749
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalogue of variable stars compiled from the data taken for the University of New South Wales Extrasolar Planet Search. From 2004 October to 2007 May, 25 target fields were each observed for one to four months, resulting in ~87000 high-precision light curves with 16004400 data points. We have extracted a total of 850 variable light curves, 659 of which do not have a counterpart in the General Catalogue of Variable Stars, the New Suspected Variables catalogue or the All Sky Automated Survey southern variable star catalogue. The catalogue is detailed here, and includes 142 Algol-type eclipsing binaries, 23 beta Lyrae-type eclipsing binaries, 218 contact eclipsing binaries, 53 RR Lyrae stars, 26 Cepheid stars, 13 rotationally variable active stars, 153 uncategorized pulsating stars with periods <10d, including delta Scuti stars, and 222 long period variables with variability on time-scales of >10d.
- ID:
- ivo://CDS.VizieR/J/AJ/160/279
- Title:
- Untangling the Galaxy. II. Structure within 3kpc
- Short Name:
- J/AJ/160/279
- Date:
- 09 Mar 2022 22:00:00
- Publisher:
- CDS
- Description:
- We present the results of the hierarchical clustering analysis of the Gaia DR2 data to search for clusters, comoving groups, and other stellar structures. The current paper builds on the sample from the previous work, extending it in distance from 1 to 3kpc and increasing the number of identified structures up to 8292. To aid in the analysis of the population properties, we developed a neural network called Auriga to robustly estimate the age, extinction, and distance of a stellar group based on the input photometry and parallaxes of the individual members. We apply Auriga to derive the properties of not only the structures found in this paper, but also previously identified open clusters. Through this work, we examine the temporal structure of the spiral arms. Specifically, we find that the Sagittarius Arm has moved by >500pc in the last 100Myr and the Perseus Arm has been experiencing a relative lull in star formation activity over the last 25Myr. We confirm the findings of the previous paper on the transient nature of the spiral arms, with the timescale of transition of a few 100Myr. Finally, we find a peculiar ~1Gyr old stream of stars that appears to be heliocentric. Its origin is unclear.
