- ID:
- ivo://CDS.VizieR/J/ApJ/890/131
- Title:
- Follow-up of candidate counterparts of S190814bv
- Short Name:
- J/ApJ/890/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On 2019 August 14, the Advanced LIGO and Virgo interferometers detected the high-significance gravitational wave (GW) signal S190814bv. The GW data indicated that the event resulted from a neutron star-black hole (NSBH) merger, or potentially a low-mass binary BH merger. Due to the low false-alarm rate and the precise localization (23deg^2^ at 90%), S190814bv presented the community with the best opportunity yet to directly observe an optical/near-infrared counterpart to an NSBH merger. To search for potential counterparts, the GROWTH Collaboration performed real-time image subtraction on six nights of public Dark Energy Camera images acquired in the 3 weeks following the merger, covering >98% of the localization probability. Using a worldwide network of follow-up facilities, we systematically undertook spectroscopy and imaging of optical counterpart candidates. Combining these data with a photometric redshift catalog, we ruled out each candidate as the counterpart to S190814bv and placed deep, uniform limits on the optical emission associated with S190814bv. For the nearest consistent GW distance, radiative transfer simulations of NSBH mergers constrain the ejecta mass of S190814bv to be M_ej_<0.04M_{sun}_ at polar viewing angles, or M_ej_<0.03M_{sun}_ if the opacity is {kappa}<2cm^2^g^-1^. Assuming a tidal deformability for the NS at the high end of the range compatible with GW170817 results, our limits would constrain the BH spin component aligned with the orbital momentum to be {chi}<0.7 for mass ratios Q<6, with weaker constraints for more compact NSs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/831/133
- Title:
- Follow-up of probable young star ASASSN-15qi
- Short Name:
- J/ApJ/831/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Outbursts on young stars are usually interpreted as accretion bursts caused by instabilities in the disk or the star-disk connection. However, some protostellar outbursts may not fit into this framework. In this paper, we analyze optical and near-infrared spectra and photometry to characterize the 2015 outburst of the probable young star ASASSN-15qi. The ~3.5mag brightening in the V band was sudden, with an unresolved rise time of less than one day. The outburst decayed exponentially by 1mag for 6 days and then gradually back to the pre-outburst level after 200 days. The outburst is dominated by emission from ~10000K gas. An explosive release of energy accelerated matter from the star in all directions, seen in a spectacular cool, spherical wind with a maximum velocity of 1000km/s. The wind and hot gas both disappeared as the outburst faded and the source returned to its quiescent F-star spectrum. Nebulosity near the star brightened with a delay of 10-20 days. Fluorescent excitation of H_2_ is detected in emission from vibrational levels as high as v=11, also with a possible time delay in flux increase. The mid-infrared spectral energy distribution does not indicate the presence of warm dust emission, though the optical photospheric absorption and CO overtone emission could be related to a gaseous disk. Archival photometry reveals a prior outburst in 1976. Although we speculate about possible causes for this outburst, none of the explanations are compelling.
- ID:
- ivo://CDS.VizieR/J/ApJ/863/109
- Title:
- Follow-up optical observations of the SNIc SN2014L
- Short Name:
- J/ApJ/863/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopic and photometric observations of the nearby type Ic supernova (SN Ic) SN 2014L. This SN was discovered by the Tsinghua-NAOC Transient Survey (TNTS) in the nearby type-Sc spiral galaxy M99 (NGC 4254). Fitting to the early-time light curve indicates that SN 2014L was detected at only a few hours after the shock breakout, and it reached a peak brightness of M_V_=-17.73+/-0.28mag (L=[2.06+/-0.50]x10^42^erg/s) approximately 13 days later. SN 2014L shows a close resemblance to SN 2007gr in the photometric evolution, while it shows stronger absorption features of intermediate-mass elements (especially CaII) in the early-time spectra. Based on simple modeling of the observed light curves, we derived the mass of synthesized ^56^Ni as M_Ni_=0.075+/-0.025M_{sun}_, and the mass and total energy of the ejecta as M_ej_=1.00+/-0.20M_{sun}_ and E_ej_=1.45+/-0.25 foe, respectively. Given these typical explosion parameters, the early detection, and the extensive observations, we suggest that SN 2014L could be a template sample for the investigation of SNe Ic.
- ID:
- ivo://CDS.VizieR/J/AJ/152/136
- Title:
- Follow-up photometry and spectroscopy of KELT-17
- Short Name:
- J/AJ/152/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of a hot Jupiter transiting the V=9.23mag main-sequence A-star KELT-17 (BD+14 1881). KELT-17b is a 1.31_-0.29_^+0.28^M_J_, 1.525_-0.060_^+0.065^R_J_ hot-Jupiter in a 3.08-day period orbit misaligned at -115.9{deg}+/-4.1{deg} to the rotation axis of the star. The planet is confirmed via both the detection of the radial velocity orbit, and the Doppler tomographic detection of the shadow of the planet during two transits. The nature of the spin-orbit misaligned transit geometry allows us to place a constraint on the level of differential rotation in the host star; we find that KELT-17 is consistent with both rigid-body rotation and solar differential rotation rates ({alpha}<0.30 at 2{sigma} significance). KELT-17 is only the fourth A-star with a confirmed transiting planet, and with a mass of 1.635_-0.061_^+0.066^M_{Sun}_, an effective temperature of 7454+/-49K, and a projected rotational velocity of vsinI_*_=44.2_-1.3_^+1.5^km/s; it is among the most massive, hottest, and most rapidly rotating of known planet hosts.
- ID:
- ivo://CDS.VizieR/J/ApJ/750/84
- Title:
- Follow-up photometry and velocity of Qatar 2
- Short Name:
- J/ApJ/750/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery and initial characterization of Qatar-2b, a hot Jupiter transiting a V = 13.3 mag K dwarf in a circular orbit with a short period, P_b_= 1.34 days. The mass and radius of Qatar-2b are M_P_ = 2.49 M_J_ and R_P_= 1.14 R_J_, respectively. Radial-velocity monitoring of Qatar-2 over a span of 153 days revealed the presence of a second companion in an outer orbit. The Systemic Console yielded plausible orbits for the outer companion, with periods on the order of a year and a companion mass of at least several M_J_. Thus, Qatar-2 joins the short but growing list of systems with a transiting hot Jupiter and an outer companion with a much longer period. This system architecture is in sharp contrast to that found by Kepler for multi-transiting systems, which are dominated by objects smaller than Neptune, usually with tightly spaced orbits that must be nearly coplanar.
- ID:
- ivo://CDS.VizieR/J/ApJ/734/109
- Title:
- Follow-up photometry of HAT-P-27
- Short Name:
- J/ApJ/734/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HAT-P-27b, an exoplanet transiting the moderately bright G8 dwarf star GSC 0333-00351 (V=12.214). The orbital period is 3.039586+/-0.000012 days, the reference epoch of transit is 2455186.01879+/-0.00054 (BJD), and the transit duration is 0.0705+/-0.0019 days. The host star with its effective temperature 5300+/-90K is somewhat cooler than the Sun and is more metal-rich with a metallicity of +0.29+/-0.10. Its mass is 0.94+/-0.04M_{sun}_ and radius is 0.90^+0.05^_-0.04_R_{sun}_. For the planetary companion we determine a mass of 0.660+/-0.033M_J_ and radius of 1.038^+0.077^_-0.058_R_J_. For the 30 known transiting exoplanets between 0.3M_J_ and 0.8M_J_, a negative correlation between host star metallicity and planetary radius and an additional dependence of planetary radius on equilibrium temperature are confirmed at a high level of statistical significance.
- ID:
- ivo://CDS.VizieR/J/AJ/145/5
- Title:
- Follow-up photometry of HATS-1
- Short Name:
- J/AJ/145/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HATS-1b, a transiting extrasolar planet orbiting the moderately bright V=12.05 G dwarf star GSC 6652-00186, and the first planet discovered by HATSouth, a global network of autonomous wide-field telescopes. HATS-1b has a period of P{approx}3.4465days, mass of M_p_{approx}1.86M_J_, and radius of R_p_{approx}1.30R_J_. The host star has a mass of 0.99M_{sun}_ and radius of 1.04R_{sun}_. The discovery light curve of HATS-1b has near-continuous coverage over several multi-day timespans, demonstrating the power of using a global network of telescopes to discover transiting planets.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/107
- Title:
- Follow-up photometry of M101 OT2015-1
- Short Name:
- J/ApJ/834/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of optical, near-infrared, and mid-infrared observations of M101 OT2015-1 (PSN J14021678+5426205), a luminous red transient in the Pinwheel galaxy (M101), spanning a total of 16 years. The light curve showed two distinct peaks with absolute magnitudes M_r_<=-12.4 and M_r_~-12, on 2014 November 11 and 2015 February 17, respectively. The spectral energy distributions during the second maximum show a cool outburst temperature of ~3700K and low expansion velocities (~-300km/s) for the HI, CaII, BaII, and KI lines. From archival data spanning 15-8 years before the outburst, we find a single source consistent with the optically discovered transient, which we attribute to being the progenitor; it has properties consistent with being an F-type yellow supergiant with L~8.7x10^4^L_{sun}_, T_eff_~7000K, and an estimated mass of M1=18+/-1M_{sun}_. This star has likely just finished the H-burning phase in the core, started expanding, and is now crossing the Hertzsprung gap. Based on the combination of observed properties, we argue that the progenitor is a binary system, with the more evolved system overfilling the Roche lobe. Comparison with binary evolution models suggests that the outburst was an extremely rare phenomenon, likely associated with the ejection of the common envelope of a massive star. The initial mass of the primary fills the gap between the merger candidates V838 Mon (5-10M_{sun}_) and NGC 4490-OT (30M_{sun}_).
- ID:
- ivo://CDS.VizieR/J/ApJ/742/L18
- Title:
- Follow-up photometry of the SN IIb PTF 11eon
- Short Name:
- J/ApJ/742/L18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On 2011 May 31 UT a supernova (SN) exploded in the nearby galaxy M51 (the Whirlpool Galaxy). We discovered this event using small telescopes equipped with CCD cameras and also detected it with the Palomar Transient Factory survey, rapidly confirming it to be a Type II SN. Here, we present multi-color ultraviolet through infrared photometry which is used to calculate the bolometric luminosity and a series of spectra. Our early-time observations indicate that SN 2011dh resulted from the explosion of a relatively compact progenitor star. Rapid shock-breakout cooling leads to relatively low temperatures in early-time spectra, compared to explosions of red supergiant stars, as well as a rapid early light curve decline. Optical spectra of SN 2011dh are dominated by H lines out to day 10 after explosion, after which HeI lines develop. This SN is likely a member of the cIIb (compact IIb) class, with progenitor radius larger than that of SN 2008ax and smaller than the eIIb (extended IIb) SN 1993J progenitor. Our data imply that the object identified in pre-explosion Hubble Space Telescope images at the SN location is possibly a companion to the progenitor or a blended source, and not the progenitor star itself, as its radius (~10^13^cm) would be highly inconsistent with constraints from our post-explosion spectra.
- ID:
- ivo://CDS.VizieR/J/ApJ/874/82
- Title:
- Follow-up photometry & spectroscopy of PTF14jg
- Short Name:
- J/ApJ/874/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the outbursting source PTF 14jg, which, prior to the onset of its late 2013 eruption, was a faint, unstudied, and virtually uncataloged star. The salient features of the PTF 14jg outburst are (i) projected location near the W4 HII region and radial velocity consistent with physical association; (ii) a light curve that underwent an ~6-7mag optical (R-band) through mid-infrared (L-band) brightening on a timescale of a few months, peaked and then faded by ~3mag, but plateaued still >3.5mag above quiescence by ~8 months post-peak, lasting to at least 4yr after eruption; (iii) strong outflow signatures with velocities reaching -530km/s; (iv) a low-gravity and broad (~100-150km/s FWHM) optical absorption-line spectrum that systematically changes its spectral type with wavelength; (v) lithium; and (vi) ultraviolet and infrared excess. We tentatively identify the outburst as exhibiting characteristics of a young star FU Ori event. However, the burst would be unusually hot, with an absorption spectrum exhibiting high-excitation (~11000-15000K) lines in the optical and no evidence of CO in the near-infrared, in addition to exhibiting an unusual light curve. We thus also consider alternative scenarios-including various forms of novae, nuclear-burning instabilities, massive star events, and mergers-finding them all inferior to the atypically hot FU Ori star classification. The source eventually may be interpreted as a new category of young star outburst with a larger amplitude and shorter rise time than most FU Ori-like events.
