We report the results of a multi-year spectroscopic and photometric survey of novae in M31 that resulted in a total of 53 spectra of 48 individual nova candidates. Two of these, M31N 1995-11e and M31N 2007-11g, were revealed to be long-period Mira variables, not novae. These data double the number of spectra extant for novae in M31 through the end of 2009 and bring to 91 the number of M31 novae with known spectroscopic classifications. We find that 75 novae (82%) are confirmed or likely members of the FeII spectroscopic class, with the remaining 16 novae (18%) belonging to the He/N (and related) classes. These numbers are consistent with those found for Galactic novae. We find no compelling evidence that spectroscopic class depends sensitively on spatial position or population within M31 (i.e., bulge versus disk), although the distribution for He/N systems appears slightly more extended than that for the FeII class. We confirm the existence of a correlation between speed class and ejection velocity (based on line width), as in the case of Galactic novae. Follow-up photometry allowed us to determine light-curve parameters for a total of 47 of the 91 novae with known spectroscopic class. We confirm that more luminous novae generally fade the fastest and that He/N novae are typically faster and brighter than their FeII counterparts. In addition, we find a weak dependence of nova speed class on position in M31, with the spatial distribution of the fastest novae being slightly more extended than that of slower novae.
We describe a survey for variable QSOs carried out for 15 years with the UK Schmidt telescope, using IIIaJ plates exposed behind a Schott GG395 filter. Objects brighter than B=21.0 on a reference plate and displaying a peak to peak amplitude of variability larger than B=0.35mag are selected. Plates in U, V, R and I were also obtained.
Circumstellar environments of oxygen-rich stars are among the strongest SiO maser emitters. Physical processes such as collisions, infrared pumping, and overlaps favor the inversion of level population and produce maser emission at different vibrational states. Despite numerous observational and theoretical efforts, we still do not have a unified picture including all of the physical processes involved in SiO maser emission. The aim of this work is to provide homogeneous data in a large sample of oxygen-rich stars. We present a survey of 67 oxygen-rich stars from 7 to 1mm, in their rotational transitions from J=1-0 to J=5-4, for vibrational numbers v from 0 to 6 in the three main SiO isotopologs. We have used one of the 34 m NASA antennas at Robledo and the IRAM 30m radio telescope. The first tentative detection of a v=6 line is reported, as well as the detection of new maser lines. The highest vibrational levels seem confined to small volumes, presumably close to the stars. The J=1-0, v=2 line flux is greater than the corresponding v=1 in almost half of the sample, which may confirm a predicted dependence on the pulsation cycle. This database is potentially useful in models which should consider most of the physical agents, time dependency, and mass-loss rates. As a by-product, we report detections of 27 thermal rotational lines from other molecules, including isotopologs of SiS, H_2_S, SO, SO_2_, and NaCl.
We explore the impact of outer stellar companions on the occurrence rate of giant planets detected with radial velocities. We searched for stellar and planetary companions to a volume-limited sample of solar-type stars within 25pc. Using adaptive optics imaging observations from the Lick 3m and Palomar 200" Telescopes, we characterized the multiplicity of our sample stars, down to the bottom of the main sequence. With these data, we confirm field star multiplicity statistics from previous surveys. We additionally combined three decades of radial velocity (RV) data from the California Planet Search with newly collected RV data from Keck/HIRES and the Automated Planet Finder/Levy Spectrometer to search for planetary companions in these same systems. Using an updated catalog of both stellar and planetary companions, as well as detailed injection/recovery tests to determine our sensitivity and completeness, we measured the occurrence rate of planets among the single and multiple-star systems. We found that planets with masses in the range of 0.1-10M_J_ and with semimajor axes of 0.1-10au have an occurrence rate of 0.18_-0.03_^+0.04^ planets per star when they orbit single stars and an occurrence rate of 0.12{+/-}0.04 planets per star when they orbit a star in a binary system. Breaking the sample down by the binary separation, we found that only one planet-hosting binary system had a binary separation <100au, and none had a separation <50au. These numbers yielded planet occurrence rates of 0.20_-0.06_^+0.07^ planets per star for binaries with separation aB>100au and 0.04_-0.02_^+0.04^ planets per star for binaries with separation aB<100au. The similarity in the planet occurrence rate around single stars and wide primaries implies that wide binary systems should actually host more planets than single-star systems, since they have more potential host stars. We estimated a system-wide planet occurrence rate of 0.3 planets per wide binary system for binaries with separations aB>100au. Finally, we found evidence that giant planets in binary systems have a different semimajor-axis distribution than their counterparts in single-star systems. The planets in the single-star sample had a significantly higher occurrence rate outside of 1au than inside 1au by nearly 4{sigma}, in line with expectations that giant planets are most common near the snow line. However, the planets in the wide binary systems did not follow this distribution, but rather had equivalent occurrence rates interior and exterior to 1au. This may point to binary-mediated planet migration acting on our sample, even in binaries wider than 100au.
We present results from an adaptive optics survey for substellar and stellar companions to Sun-like stars. The survey targeted 266 F5-K5 stars in the 3Myr-3Gyr age range with distances of 10-190pc. Results from the survey include the discovery of two brown dwarf companions (HD 49197B and HD 203030B), 24 new stellar binaries, and a triple system. We infer that the frequency of 0.012-0.072M_{sun}_ brown dwarfs in 28-1590AU orbits around young solar analogs is 3.2^+3.1^_-2.7_% (2{sigma} limits). The result demonstrates that the deficiency of substellar companions at wide orbital separations from Sun-like stars is less pronounced than in the radial velocity "brown dwarf desert." We infer that the mass distribution of companions in 28-1590AU orbits around solar-mass stars follows a continuous dN/dM_2_{prop.to}M^-0.4^_2_ relation over the 0.01-1.0M_{sun}_ secondary mass range. While this functional form is similar to that for isolated objects less than 0.1M_{sun}_, over the entire 0.01-1.0M_{sun}_ range, the mass functions of companions and of isolated objects differ significantly. Based on this conclusion and on similar results from other direct imaging and radial velocity companion surveys in the literature, we argue that the companion mass function follows the same universal form over the entire range between 0 and 1590AU in orbital semimajor axis and ~0.01-20M_{sun}_ in companion mass. In this context, the relative dearth of substellar versus stellar secondaries at all orbital separations arises naturally from the inferred form of the companion mass function.
We explored the AllWISE catalogue of the Wide-field Infrared Survey Explorer mission and identified Young Stellar Object candidates. Reliable 2MASS and WISE photometric data combined with Planck dust opacity values were used to build our dataset and to find the best classification scheme. A sophisticated statistical method, the Support Vector Machine (SVM) is used to analyse the multi-dimensional data space and to remove source types identified as contaminants (extragalactic sources, main sequence stars, evolved stars and sources related to the interstellar medium). Objects listed in the SIMBAD database are used to identify the already known sources and to train our method. A new all-sky selection of 133,980 Class I/II YSO candidates is presented. The estimated contamination was found to be well below 1% based on comparison with our SIMBAD training set. We also compare our results to that of existing methods and catalogues. The SVM selection process successfully identified >90% of the Class I/II YSOs based on comparison with photometric and spectroscopic YSO catalogues. Our conclusion is that by using the SVM, our classification is able to identify more known YSOs of the training sample than other methods based on colour-colour and magnitude-colour selection. The distribution of the YSO candidates well correlates with that of the Planck Galactic Cold Clumps in the Taurus-Auriga-Perseus-California region.
We set out to compile a catalogue of RRab pulsating variables in the SuperWASP archive and identify candidate Blazhko effect objects within this catalogue. We analysed their light curves and power spectra for correlations in their common characteristics to further our understanding of the phenomenon. Pulsation periods were found for each SWASP RRab object using phase dispersion minimisation techniques. Low frequency periodic signals detected in the CLEAN power spectra of RRab stars were matched with modulation sidebands and combined with pairs of sidebands to produce a list of candidate Blazhko periods. A novel technique was used in an attempt to identify Blazhko effect stars by comparing scatter at different parts of the folded light curve. Pulsation amplitudes were calculated based on phase folded light curves. The SuperWASP RRab catalogue consists of 4963 objects of which 3397 are previously unknown. We discovered 983 distinct candidates for Blazhko effect objects, 613 of these being previously unknown in the literature as RR Lyrae stars, and 894 are previously unknown to be Blazhko effect stars. Correlations were investigated between the scatter of points on the light curve, the periods and amplitudes of the objects' pulsations, and those of the Blazhko effect.
SweetSpot DR1: 74 SNe Ia in 36 nights on WIYN+WHIRC
Short Name:
J/AJ/155/201
Date:
21 Oct 2021
Publisher:
CDS
Description:
SweetSpot is a 3 yr National Optical Astronomy Observatory (NOAO) survey program to observe Type Ia supernovae (SNe Ia) in the smooth Hubble flow with the WIYN High-resolution Infrared Camera (WHIRC) on the WIYN 3.5 m telescope. We present data from the first half of this survey, covering the 2011B-2013B NOAO semesters and consisting of 493 calibrated images of 74 SNe Ia observed in the rest-frame near-infrared (NIR) in the range 0.02<z<0.09. Because many observed supernovae require host-galaxy subtraction from templates taken in later semesters, this release contains only the 186 NIR (JHK_s_) data points for the 33 SNe Ia that do not require host-galaxy subtraction. The sample includes four objects with coverage beginning before the epoch of B-band maximum and 27 beginning within 20 days of B-band maximum. We also provide photometric calibration between the WIYN+WHIRC and Two Micron All-Sky Survey (2MASS) systems, along with light curves for 786 2MASS stars observed alongside the SNe Ia. This work is the first in a planned series of three SweetSpot Data Releases. Future releases will include the full set of images from all 3 yr of the survey, including host-galaxy reference images and updated data processing with host-galaxy reference subtraction. SweetSpot will provide a well-calibrated sample that will help improve our ability to standardize distance measurements to SNe Ia, examine the intrinsic optical-NIR colors of SNe Ia at different epochs, explore the nature of dust in other galaxies, and act as a stepping-stone for more distant, potentially space-based surveys.
The Swift active galactic nucleus (AGN) and Cluster Survey (SACS) uses 125deg^2^ of Swift X-ray Telescope serendipitous fields with variable depths surrounding {gamma}-ray bursts to provide a medium depth (4x10^-15^erg/cm2/s) and area survey filling the gap between deep, narrow Chandra/XMM-Newton surveys and wide, shallow ROSAT surveys. Here, we present a catalog of 22563 point sources and 442 extended sources and examine the number counts of the AGN and galaxy cluster populations. SACS provides excellent constraints on the AGN number counts at the bright end with negligible uncertainties due to cosmic variance, and these constraints are consistent with previous measurements. We use Wide-field Infrared Survey Explorer (WISE) mid-infrared (MIR) colors to classify the sources. For AGNs we can roughly separate the point sources into MIR-red and MIR-blue AGNs, finding roughly equal numbers of each type in the soft X-ray band (0.5-2keV), but fewer MIR-blue sources in the hard X-ray band (2-8keV). The cluster number counts, with 5% uncertainties from cosmic variance, are also consistent with previous surveys but span a much larger continuous flux range. Deep optical or IR follow-up observations of this cluster sample will significantly increase the number of higher-redshift (z>0.5) X-ray-selected clusters.
We study 203 (of 442) Swift AGN and Cluster Survey extended X-ray sources located in the SDSS DR8 footprint to search for galaxy over-densities in three-dimensional space using SDSS galaxy photometric redshifts and positions near the Swift cluster candidates. We find 104 Swift clusters with a >3{sigma} galaxy over-density. The remaining targets are potentially located at higher redshifts and require deeper optical follow-up observations for confirmation as galaxy clusters. We present a series of cluster properties including the redshift, brightest cluster galaxy (BCG) magnitude, BCG-to-X-ray center offset, optical richness, and X-ray luminosity. We also detect red sequences in ~85% of the 104 confirmed clusters. The X-ray luminosity and optical richness for the SDSS confirmed Swift clusters are correlated and follow previously established relations. The distribution of the separations between the X-ray centroids and the most likely BCG is also consistent with expectation. We compare the observed redshift distribution of the sample with a theoretical model, and find that our sample is complete for z<~0.3 and is still 80% complete up to z~0.4, consistent with the SDSS survey depth. These analysis results suggest that our Swift cluster selection algorithm has yielded a statistically well-defined cluster sample for further study of cluster evolution and cosmology. We also match our SDSS confirmed Swift clusters to existing cluster catalogs, and find 42, 23, and 1 matches in optical, X-ray, and Sunyaev-Zel'dovich catalogs, respectively, and so the majority of these clusters are new detections.
