- ID:
- ivo://CDS.VizieR/J/ApJ/877/29
- Title:
- Opt & NIR SMARTS/ANDICAM photometry for DQ Tau
- Short Name:
- J/ApJ/877/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multiepoch optical and near-infrared (NIR) photometry and spectroscopy of the spectroscopic binary T Tauri star DQ Tau. The photometric monitoring, obtained using SMARTS ANDICAM, recovers the previously seen correlation between optical flux and the 15.8d binary orbital period, with blue flux peaks occurring close to most observed periastron passages. For the first time, we find an even more consistent correlation between orbital period and NIR brightness and color. The onset of pulse events in the NIR precedes those in the optical by a few days, on average, with the rise usually starting near apastron orbital phase. We further obtained five epochs of spectroscopy using Infrared Telescope Facility (IRTF) SpeX, with a wavelength range of 0.8-5{mu}m, and derived spectra of the infrared excess emission. The shape and strength of the excess varies with time, with cooler and weaker characteristic dust emission (T~1100-1300K) over most of the binary orbit, and stronger/warmer dust emission (T~1600K, indicative of dust sublimation) just before periastron passage. We suggest that our results are broadly consistent with predictions of simulations of disk structure and accretion flows around close binaries, with the varying dust emission possibly tracing the evolution of accretion streams falling inward through a circumbinary disk cavity and feeding the accretion pulses traced by the optical photometry and NIR emission lines. However, our results also show more complicated behavior that is not fully explained by this simple picture, and will require further observations and modeling to fully interpret.
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- ID:
- ivo://CDS.VizieR/J/ApJ/872/42
- Title:
- Opt. spectroscopy of redback ms pulsar binaries
- Short Name:
- J/ApJ/872/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first optical spectroscopy of five confirmed (or strong candidate) redback millisecond pulsar binaries, obtaining complete radial velocity curves for each companion star. The properties of these millisecond pulsar binaries with low-mass, hydrogen-rich companions are discussed in the context of the 14 confirmed and 10 candidate field redbacks. We find that the neutron stars in redbacks have a median mass of 1.78+/-0.09M_{sun}_ with a dispersion of {sigma}=0.21+/-0.09. Neutron stars with masses in excess of 2M_{sun}_ are consistent with, but not firmly demanded by, current observations. Redback companions have median masses of 0.36+/-0.04M_{sun}_ with a scatter of {sigma}=0.15+/-0.04M_{sun}_, and a tail possibly extending up to 0.7-0.9M_{sun}_. Candidate redbacks tend to have higher companion masses than confirmed redbacks, suggesting a possible selection bias against the detection of radio pulsations in these more massive candidate systems. The distribution of companion masses between redbacks and the less massive black widows continues to be strongly bimodal, which is an important constraint on evolutionary models for these systems. Among redbacks, the median efficiency of converting the pulsar spin-down energy to {gamma}-ray luminosity is ~10%.
- ID:
- ivo://CDS.VizieR/J/ApJ/873/92
- Title:
- Opt. & UV evolution of the TDE iPTF15af
- Short Name:
- J/ApJ/873/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multiwavelength observations of the tidal disruption event (TDE) iPTF15af, discovered by the intermediate Palomar Transient Factory survey at redshift z=0.07897. The optical and ultraviolet (UV) light curves of the transient show a slow decay over 5 months, in agreement with previous optically discovered TDEs. It also has a comparable blackbody peak luminosity of L_peak_~1.5x10^44^erg/s. The inferred temperature from the optical and UV data shows a value of (3-5)x10^4^K. The transient is not detected in X-rays up to L_X_<3x10^42^erg/s within the first 5 months after discovery. The optical spectra exhibit two distinct broad emission lines in the HeII region, and at later times also H{alpha} emission. Additionally, emission from [NIII] and [OIII] is detected, likely produced by the Bowen fluorescence effect. UV spectra reveal broad emission and absorption lines associated with high-ionization states of NV, CIV, SiIV, and possibly PV. These features, analogous to those of broad absorption line quasars (BAL QSOs), require an absorber with column densities N_H_>10^23^cm^-2^. This optically thick gas would also explain the nondetection in soft X-rays. The profile of the absorption lines with the highest column density material at the largest velocity is opposite that of BAL QSOs. We suggest that radiation pressure generated by the TDE flare at early times could have provided the initial acceleration mechanism for this gas. Spectral UV line monitoring of future TDEs could test this proposal.
- ID:
- ivo://CDS.VizieR/J/AJ/159/133
- Title:
- Orbital elements of TNOs from the Dark Energy Survey
- Short Name:
- J/AJ/159/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The outer solar system contains a large number of small bodies (known as trans-Neptunian objects or TNOs) that exhibit diverse types of dynamical behavior. The classification of bodies in this distant region into dynamical classes-subpopulations that experience similar orbital evolution-aids in our understanding of the structure and formation of the solar system. In this work, we propose an updated dynamical classification scheme for the outer solar system. This approach includes the construction of a new (automated) method for identifying mean motion resonances. We apply this algorithm to the current data set of TNOs observed by the Dark Energy Survey (DES) and present a working classification for all of the DES TNOs detected to date. Our classification scheme yields 1 inner centaur, 19 outer centaurs, 21 scattering disk objects, 47 detached TNOs, 48 securely resonant objects, 7 resonant candidates, and 97 classical belt objects. Among the scattering and detached objects, we detect 8 TNOs with semimajor axes greater than 150au.
- ID:
- ivo://CDS.VizieR/J/A+A/399/271
- Title:
- Oscillations in the PMS star V346 Ori
- Short Name:
- J/A+A/399/271
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of periodicities in the light curve of the Pre-Main Sequence (PMS) Herbig Ae star V346 Ori. We interpret variations in the light curve of the star as the superposition of at least two periodic signals that result from delta Scuti-type stellar oscillations. The computation of linear non-adiabatic radial pulsation models for PMS stars reproduces these periods for a 1.55M_{sun}_ star with Teff=7410K and log(L/L_{sun}_)=0.74 pulsating in the fundamental and in the second overtone. If our assumption of radial oscillations is indeed correct, the star's location on the HR diagram places it at a distance significantly smaller than that of the Orion star forming region, hence raising questions regarding the evolutionary status of V346 Ori. Observations with better time sampling and spanning a longer period of time are needed if the latter question is to be addressed fully.
- ID:
- ivo://CDS.VizieR/II/207A
- Title:
- Palomar-Green catalog UV-excess stellar objects
- Short Name:
- II/207A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Palomar-Green Catalogue of UV-excess stellar objects provides positions accurate to about 8arcsec in each coordinate, photographic B-magnitudes accurate to 0.29mag, spectral types, some cross-references, and photoelectric broad-band, multichannel, and Stroemgren colors when available. Of the 1874 objects in the catalogue as published in 1986 (1878 in this version), 1715 comprise a statistically complete sample covering 10714 square degrees from 266 fields taken on the Palomar 18-inch Schmidt telescope. Limiting magnitudes vary from field to field, ranging from 15.49 to 16.67. The overall completeness is estimated to be 84%, but that figure and the relative contributions of magnitude, color, and accidental errors vary depending on the magnitude and color distribution of the spectroscopic subsample.
- ID:
- ivo://CDS.VizieR/J/A+A/419/533
- Title:
- Pal 13 UBV, proper motions and radial velocities
- Short Name:
- J/A+A/419/533
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recently, combining radial velocities from Keck/HIRES echelle spectra with published proper motion membership probabilities, Cote et al. (2002ApJ...574..783C) observed a sample of 21 stars, probable members of Palomar 13, a globular cluster in the Galactic halo. Their projected velocity dispersion sigma_p_=2.2+/-0.4km/s gives a mass-to-light ratio M/L_V_=40^+24^_-17_, about one order of magnitude larger than the usual estimate for globular clusters. We present here radial velocities measured from three different CCD frames of commissioning observations obtained with the new ESO/VLT instrument FLAMES (Fibre Large Array Multi Element Spectrograph). From these data, now publicly available, we measure the homogeneous radial velocities of eight probable members of this globular cluster. A new projected velocity dispersion sigma_p_=0.6-0.9+/-0.3km/s implies Palomar 13 mass-to-light ratio M/L_V_=3-7, similar to the usual value for globular clusters. We discuss briefly the two most obvious reasons for the previous unusual mass-to-light ratio finding: binaries, now clearly detected, and more homogeneous data from the multi-fibre FLAMES spectrograph.
- ID:
- ivo://CDS.VizieR/J/ApJ/782/42
- Title:
- Panchromatic observations of PTF11qcj
- Short Name:
- J/ApJ/782/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery, classification, and extensive panchromatic (from radio to X-ray) follow-up observations of PTF11qcj, a supernova (SN) discovered by the Palomar Transient Factory (PTF). Our observations with the Karl G. Jansky Very Large Array show that this event is radio-loud: PTF11qcj reached a radio peak luminosity comparable to that of the famous gamma-ray-burst-associated SN 1998bw (L_5GHz_{approx}10^29^erg/s/Hz). PTF11qcj is also detected in X-rays with the Chandra Observatory, and in the infrared band with Spitzer. Our multi-wavelength analysis probes the SN interaction with circumstellar material. The radio observations suggest a progenitor mass-loss rate of ~10^-4^M_{sun}_/yr*(v_w_/1000km/s), and a velocity of {approx}0.3-0.5c for the fastest moving ejecta (at {approx}10 days after explosion). However, these estimates are derived assuming the simplest model of SN ejecta interacting with a smooth circumstellar wind, and do not account for possible inhomogeneities in the medium and asphericity of the explosion. The radio data show deviations from such a simple model, as well as a late-time re-brightening. The X-ray flux from PTF11qcj is compatible with the high-frequency extrapolation of the radio synchrotron emission (within the large uncertainties). A light echo from pre-existing dust is in agreement with our infrared data. Our pre-explosion data from the PTF suggest that a precursor eruption of absolute magnitude M_r_{approx}-13mag may have occurred {approx}2.5yr prior to the SN explosion. Overall, PTF11qcj fits the expectations from the explosion of a Wolf-Rayet star. Precursor eruptions may be a feature characterizing the final pre-explosion evolution of such stars.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A163
- Title:
- Pan-STARRS lens candidates from neural networks
- Short Name:
- J/A+A/644/A163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a systematic search for wide-separation (with Einstein radius ~1.5"), galaxy-scale strong lenses in the 30000 sq.deg of the Pan-STARRS 3pi survey on the Northern sky. With long time delays of a few days to weeks, these types of systems are particularly well-suited for catching strongly lensed supernovae with spatially-resolved multiple images and offer new insights on early-phase supernova spectroscopy and cosmography. We produced a set of realistic simulations by painting lensed COSMOS sources on Pan-STARRS image cutouts of lens luminous red galaxies (LRGs) with redshift and velocity dispersion known from the sloan digital sky survey (SDSS). First, we computed the photometry of mock lenses in gri bands and applied a simple catalog-level neural network to identify a sample of 1050207 galaxies with similar colors and magnitudes as the mocks. Second, we trained a convolutional neural network (CNN) on Pan-STARRS gri image cutouts to classify this sample and obtain sets of 105760 and 12382 lens candidates with scores of pCNN>0.5 and >0.9, respectively. Extensive tests showed that CNN performances rely heavily on the design of lens simulations and the choice of negative examples for training, but little on the network architecture. The CNN correctly classified 14 out of 16 test lenses, which are previously confirmed lens systems above the detection limit of Pan-STARRS. Finally, we visually inspected all galaxies with pCNN>0.9 to assemble a final set of 330 high-quality newly-discovered lens candidates while recovering 23 published systems. For a subset, SDSS spectroscopy on the lens central regions proves that our method correctly identifies lens LRGs at z~0.1-0.7. Five spectra also show robust signatures of high-redshift background sources, and Pan-STARRS imaging confirms one of them as a quadruply-imaged red source at z_s_=1.185, which is likely a recently quenched galaxy strongly lensed by a foreground LRG at z_d_=0.3155. In the future, high-resolution imaging and spectroscopic follow-up will be required to validate Pan-STARRS lens candidates and derive strong lensing models. We also expect that the efficient and automated two-step classification method presented in this paper will be applicable to the ~4 mag deeper gri stacks from the Rubin Observatory Legacy Survey of Space and Time (LSST) with minor adjustments.
- ID:
- ivo://CDS.VizieR/J/ApJ/794/23
- Title:
- Pan-STARRS1 transients optical photometry
- Short Name:
- J/ApJ/794/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the past decade, several rapidly evolving transients have been discovered whose timescales and luminosities are not easily explained by traditional supernovae (SNe) models. The sample size of these objects has remained small due, at least in part, to the challenges of detecting short timescale transients with traditional survey cadences. Here we present the results from a search within the Pan-STARRS1 Medium Deep Survey (PS1-MDS) for rapidly evolving and luminous transients. We identify 10 new transients with a time above half-maximum (t_1/2_) of less than 12 days and -16.5>M>-20 mag. This increases the number of known events in this region of SN phase space by roughly a factor of three. The median redshift of the PS1-MDS sample is z=0.275 and they all exploded in star-forming galaxies. In general, the transients possess faster rise than decline timescale and blue colors at maximum light (g_P1_-r_P1_<~-0.2). Best-fit blackbodies reveal photospheric temperatures/radii that expand/cool with time and explosion spectra taken near maximum light are dominated by a blue continuum, consistent with a hot, optically thick, ejecta. We find it difficult to reconcile the short timescale, high peak luminosity (L>10^43^ erg/s), and lack of UV line blanketing observed in many of these transients with an explosion powered mainly by the radioactive decay of ^56^Ni. Rather, we find that many are consistent with either (1) cooling envelope emission from the explosion of a star with a low-mass extended envelope that ejected very little (<0.03 M_{sun}_) radioactive material, or (2) a shock breakout within a dense, optically thick, wind surrounding the progenitor star. After calculating the detection efficiency for objects with rapid timescales in the PS1-MDS we find a volumetric rate of 4800-8000 events/yr/Gpc^3^ (4%-7% of the core-collapse SN rate at z=0.2).
