- ID:
- ivo://CDS.VizieR/J/ApJ/886/L14
- Title:
- Gemini/FLAMINGOS-2 NIR spectra of V1047 Cen
- Short Name:
- J/ApJ/886/L14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Fourteen years after its eruption as a classical nova (CN), V1047 Cen (Nova Cen 2005) began an unusual re-brightening in 2019 April. The amplitude of the brightening suggests that this is a dwarf nova (DN) eruption in a CN system. Very few CNe have had DN eruptions within decades of the main CN outburst. The 14yr separating the CN and DN eruptions of V1047 Cen is the shortest of all instances recorded thus far. Explaining this rapid succession of CN and DN outbursts in V1047 Cen may be challenging within the framework of standard theories for DN outbursts. Following a CN eruption, the mass accretion rate is believed to remain high (dM/dt~10^-8^M_{sun}_/yr) for a few centuries, due to the irradiation of the secondary star by the still-hot surface of the white dwarf. Thus a DN eruption is not expected to occur during this high mass accretion phase as DN outbursts, which result from thermal instabilities in the accretion disk, and arise during a regime of low mass accretion rate (dM/dt~10^-10^M_{sun}_/yr). Here we present near-infrared spectroscopy to show that the present outburst is most likely a DN eruption, and discuss the possible reasons for its early occurrence. Even if the present re-brightening is later shown to be due to a cause other than a DN outburst, the present study provides invaluable documentation of this unusual event.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/649/A72
- Title:
- GW190814 observations taken with MeerLICHT
- Short Name:
- J/A+A/649/A72
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The Advanced LIGO and Virgo gravitational wave observatories detected a signal on 2019 August 14 during their third observing run, named GW190814. A large number of electromagnetic facilities conducted follow-up campaigns in the search for a possible counterpart to the gravitational wave event, which was made especially promising given the early source classification of a neutron star-black hole merger. We present the results of the GW follow-up campaign taken with the wide-field optical telescope MeerLICHT, located at the South African Astronomical Observatory Sutherland site. We use our results to constrain possible kilonova models. MeerLICHT observed more than 95% of the probability localisation each night for over a week in three optical bands (u,q,i) with our initial observations beginning almost 2 hours after the GW detection. We describe the search for new transients in MeerLICHT data and investigate how our limiting magnitudes can be used to constrain an AT2017gfo-like kilonova. A single new transient was found in our analysis of MeerLICHT data, which we exclude from being the electromagnetic counterpart to GW190814 owing to the existence of a spatially unresolved source at the coordinates of the transient in archival data. Using our limiting magnitudes, the confidence with which we can exclude the presence of an AT2017gfo-like kilonova at the distance of GW190814 was low (<10^-4^).
- ID:
- ivo://CDS.VizieR/J/ApJ/830/30
- Title:
- HDS spectrum of nova V2659 Cyg (Nova Cyg 2014)
- Short Name:
- J/ApJ/830/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on high-dispersion spectroscopy results of a classical nova V2659 Cyg (Nova Cyg 2014) that are taken 33.05 days after the V-band maximum. The spectrum shows two distinct blueshifted absorption systems originating from H I, Fe II, Ca II, etc. The radial velocities of the absorption systems are -620km/s, and -1100 to -1500km/s. The higher velocity component corresponds to the P-Cygni absorption features frequently observed in low-resolution spectra. Much larger numbers of absorption lines are identified at the lower velocity. These mainly originate from neutral or singly ionized Fe-peak elements (Fe I, Ti II, Cr II, etc.). Based on the results of our spectroscopic observations, we discuss the structure of the ejecta of V2659 Cyg. We conclude that the low- and high-velocity components are likely to be produced by the outflow wind and the ballistic nova ejecta, respectively.
- ID:
- ivo://CDS.VizieR/III/174
- Title:
- High Resolution Atlas of Symbiotic Stars
- Short Name:
- III/174
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains a high resolution atlas of both northern and southern sky symbiotic stars. It represents an all-sky optical survey of symbiotic stars using Echelle spectrometers. A summary of the stars with positions and a summary of spectra available are included. The wavelength resolution is better than 0.01 nm. The emission lines in this catalog were chosen to allow the determination of global values for the density and temperature of the nebula, as well as the temperature of the ionizing source. Note that some of the spectra with date marked by "++++" in the "ObsDate" column of the "spectra.dat" file are not in the original publications (mostly "low resolution" spectra)
- ID:
- ivo://CDS.VizieR/J/ApJS/227/1
- Title:
- HST survey for novae in M87. I. VI LCs
- Short Name:
- J/ApJS/227/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hubble Space Telescope has imaged the central part of M87 over a 10 week span, leading to the discovery of 32 classical novae (CNe) and nine fainter, likely very slow, and/or symbiotic novae. In this first paper of a series, we present the M87 nova finder charts, and the light and color curves of the novae. We demonstrate that the rise and decline times, and the colors of M87 novae are uncorrelated with each other and with position in the galaxy. The spatial distribution of the M87 novae follows the light of the galaxy, suggesting that novae accreted by M87 during cannibalistic episodes are well-mixed. Conservatively using only the 32 brightest CNe we derive a nova rate for M87: 363_-45_^+33^ novae yr^-1^. We also derive the luminosity-specific classical nova rate for this galaxy, which is 7.88_-2.6_^+2.3^yr^-1^/10^10^L_{sun},K_. Both rates are 3-4 times higher than those reported for M87 in the past, and similarly higher than those reported for all other galaxies. We suggest that most previous ground-based surveys for novae in external galaxies, including M87, miss most faint, fast novae, and almost all slow novae near the centers of galaxies.
- ID:
- ivo://CDS.VizieR/J/PAZh/26/695
- Title:
- IR photometry of V1016 Cyg and HM Sge
- Short Name:
- J/PAZh/26/695
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- JHKLM photometry of two symbiotic novae, V1016 Cyg and HM Sge in 1978-1999 is presented.
- ID:
- ivo://CDS.VizieR/J/ApJ/761/34
- Title:
- Kinematical study of the optical ejecta of GK Per
- Short Name:
- J/ApJ/761/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a kinematical study of the optical ejecta of GK Per. It is based on proper-motion measurements of 282 knots from ~20 images spanning 25 years. Doppler shifts are also computed for 217 knots. The combination of proper motions and radial velocities allows a unique three-dimensional view of the ejecta to be obtained. The main results are as follows: (1) the outflow is a thick shell in which knots expand with a significant range of velocities, mostly between 600 and 1000 km/s, (2) kinematical ages indicate that knots have suffered only a modest deceleration since their ejection a century ago, (3) no evidence for anisotropy in the expansion rate is found, (4) velocity vectors are generally aligned along the radial direction, but a symmetric pattern of non-radial velocities is also observed at specific directions, and (5) the total H{alpha}+[N II] flux has been linearly decreasing at a rate of 2.6% per year in the past decade. The eastern nebular side is fading at a slower rate than the western side. Some of the knots were displayed a rapid change of brightness during the 2004-2011 period. Over a longer timescale, a progressive circularization and homogenization of the nebula are taking place; (6) a kinematic distance of 400+/-30 pc is determined. These results raise some problems with the previous interpretations of the evolution of GK Per. In particular, the idea of a strong interaction of the outflow with the surrounding medium in the southwest quadrant is not supported by our data.
- ID:
- ivo://CDS.VizieR/J/AJ/147/105
- Title:
- Light curve of HR Lyr over 1991-2012
- Short Name:
- J/AJ/147/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 22 yr light curve of HR Lyr, acquired with a typical cadence of 2-6 days, is examined for periodic and quasi-periodic variations. No persistent periodicities are revealed. Rather, the light curve variations often take the form of nearly linear rises and falls having typical e-folding times of about 100 days. Occasional ~0.6mag outbursts are also seen, with properties similar to those of small outbursts found in some nova-like cataclysmic variables. When the photometry is formed into yearly averages, a decline of 0.012+/-0.005mag/yr is apparent, consistent with the fading of irradiation-induced Mdot following the nova. The equivalent width of H{alpha} is tabulated at three epochs over the interval 1986-2008 in order to compare with a recent result for DK Lac in which H{alpha} was found to be fading 50 yr after the nova. However, our results for such a fading in HR Lyr are inconclusive.
- ID:
- ivo://CDS.VizieR/J/AJ/161/15
- Title:
- Light curve of the dwarf nova AT 2020iko
- Short Name:
- J/AJ/161/15
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- The ongoing Zwicky Transient Facility (ZTF) survey is generating a massive alert rate from a variety of optical transients and variable stars, which are being filtered down to subsets meeting user-specified criteria by broker systems such as the Arizona-NOIRLab Temporal Analysis and Response to Events System (ANTARES). In a beta implementation of the algorithm of Soraisam et al. on ANTARES, we flagged AT 2020iko from the ZTF real-time alert stream as an anomalous source. This source is located close to a red extended Sloan Digital Sky Survey source. In the first few epochs of detection, it exhibited a V-shaped brightness profile, preceded by nondetections both in ZTF and in the All-Sky Automated Survey for Supernovae extending to 2014. Its full light curve shows a precursor event, followed by a main superoutburst and at least two rebrightenings. A low-resolution spectrum of this source points to a dwarf nova (DN) nature. Although some of the features of AT 2020iko indicate an SU UMa-type DN, its large amplitude, presence of rebrightenings, and inferred supercycle period of >~6yr are in favor of AT 2020iko being a new WZ Sge- type DN candidate, a subset of rare DNe consisting of extreme mass-ratio (<0.1) binaries with an orbital period around the period minimum. The precusor event of AT 2020iko brightened by 6.5mag, while its decay spanned 3-5mag. We speculate this superoutburst is associated with a less expanded accretion disk than in typical superoutbursts in WZ Sge systems, with the large depth of the precursor decay implying an extremely small mass ratio. To the best of our knowledge, such a precursor event has not been recorded for any DN. This result serves to demonstrate the efficacy of our real-time anomaly search algorithm.
- ID:
- ivo://CDS.VizieR/J/ApJ/773/55
- Title:
- Light curve of T Pyx from 1890 to 2011
- Short Name:
- J/ApJ/773/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery by M. Linnolt on JD 2455665.7931 (UT 2011 April 14.29) of the sixth eruption of the recurrent nova T Pyxidis. This discovery was made just as the initial fast rise was starting, so with fast notification and response by observers worldwide, the entire initial rise was covered (the first for any nova), and with high time resolution in three filters. The speed of the rise peaked at 9mag/day, while the light curve is well fit over only the first two days by a model with a uniformly expanding sphere. We also report the discovery by R. Stubbings of a pre-eruption rise starting 18 days before the eruption, peaking 1.1mag brighter than its long-time average, and then fading back toward quiescence 4 days before the eruption. This unique and mysterious behavior is only the fourth known (with V1500 Cyg, V533 Her, and T CrB) anticipatory rise closely spaced before a nova eruption. We present 19 timings of photometric minima from 1986 to 2011 February, where the orbital period is fast increasing with P/dot{P}=+313000yr. From 2008 to 2011, T Pyx had a small change in this rate of increase, so that the orbital period at the time of eruption was 0.07622950+/-0.00000008 days. This strong and steady increase of the orbital period can only come from mass transfer, for which we calculate a rate of (1.7-3.5)x10^-7^M_{sun}_/yr. We report 6116 magnitudes between 1890 and 2011, for an average B=15.59+/-0.01 from 1967 to 2011, which allows for an eruption in 2011 if the blue flux is nearly proportional to the accretion rate. The ultraviolet-optical-infrared spectral energy distribution is well fit by a power law with f_{nu}_{prop.to}{nu}^1.0^, although the narrow ultraviolet region has a tilt with a fit of f_{nu}_{prop.to}{nu}^1/3^.
