- 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).
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/311/523
- Title:
- Photometry of W UMa
- Short Name:
- J/A+A/311/523
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The physical properties of W UMa binary systems are revisited on the basis of the observational data published in the last decade and of the recent theoretical studies on angular-momentum-loss-driven secular evolution. The absolute elements (masses, radii, luminosities) are derived by an inference method and a calibration based on the available high quality spectroscopic orbits. The derived age (8Gy) agrees with the estimate of Guinan and Bradstreet from space motions. The analysis of the resulting physical parameters shows little correlation between the standard classification in A and W subtype (first proposed by Binnendijk (1970) and only related to the light curve morphology) and the evolutionary status and origin of the systems. Most A-subtype systems seem to have no evolutionary link with W-subtype ones. The relation between total mass and mass ratio for the "bona fide" sample also suggests that mass loss from the system may play an important role.
- ID:
- ivo://CDS.VizieR/J/AJ/143/99
- Title:
- Photometry of W UMa eclipsing binaries
- Short Name:
- J/AJ/143/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a BVRcIc survey of field W Ursae Majoris (UMa) binary stars and present accurate colors for 606 systems that have been observed on at least three photometric nights from a robotic observatory in southern Arizona. Comparison with earlier photometry for a subset of the systems shows good agreement. We investigate two independent methods of determining the interstellar reddening, although both have limitations that can render them less effective than desired. A subset of 101 systems shows good agreement between the two reddening methods.
- ID:
- ivo://CDS.VizieR/J/AJ/152/115
- Title:
- Pleiades members with K2 light curves. III.
- Short Name:
- J/AJ/152/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use high-quality K2 light curves for hundreds of stars in the Pleiades to better understand the angular momentum evolution and magnetic dynamos of young low-mass stars. The K2 light curves provide not only rotational periods but also detailed information from the shape of the phased light curve that was not available in previous studies. A slowly rotating sequence begins at (V-K_s_)_0_~1.1 (spectral type F5) and ends at (V-K_s_)_0_~3.7 (spectral type K8), with periods rising from ~2 to ~11 days in that interval. A total of 52% of the Pleiades members in that color interval have periods within 30% of a curve defining the slow sequence; the slowly rotating fraction decreases significantly redward of (V-K_s_)_0_=2.6. Nearly all of the slow-sequence stars show light curves that evolve significantly on timescales less than the K2 campaign duration. The majority of the FGK Pleiades members identified as photometric binaries are relatively rapidly rotating, perhaps because binarity inhibits star-disk angular momentum loss mechanisms during pre-main-sequence evolution. The fully convective late M dwarf Pleiades members (5.0<(V-K_s_)_0_<6.0) nearly always show stable light curves, with little spot evolution or evidence of differential rotation. During pre-main-sequence evolution from ~3Myr (NGC2264 age) to ~125Myr (Pleiades age), stars of 0.3M_{Sun}_ shed about half of their angular momentum, with the fractional change in period between 3 and 125Myr being nearly independent of mass for fully convective stars. Our data also suggest that very low mass binaries form with rotation periods more similar to each other and faster than would be true if drawn at random from the parent population of single stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/227/11
- Title:
- PS1 z>5.6 quasars follow-up
- Short Name:
- J/ApJS/227/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Luminous quasars at z>5.6 can be studied in detail with the current generation of telescopes and provide us with unique information on the first gigayear of the universe. Thus far, these studies have been statistically limited by the number of quasars known at these redshifts. Such quasars are rare, and therefore, wide-field surveys are required to identify them, and multiwavelength data are required to separate them efficiently from their main contaminants, the far more numerous cool dwarfs. In this paper, we update and extend the selection for the z~6 quasars presented in Banados+ (2014AJ....148...14B) using the Pan-STARRS1 (PS1) survey. We present the PS1 distant quasar sample, which currently consists of 124 quasars in the redshift range 5.6<~z<~6.7 that satisfy our selection criteria. Of these quasars, 77 have been discovered with PS1, and 63 of them are newly identified in this paper. We present the composite spectra of the PS1 distant quasar sample. This sample spans a factor of ~20 in luminosity and shows a variety of emission line properties. The number of quasars at z>5.6 presented in this work almost doubles the previously known quasars at these redshifts, marking a transition phase from studies of individual sources to statistical studies of the high-redshift quasar population, which was impossible with earlier, smaller samples.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A69
- Title:
- Radial velocity and photometry in NGC 4372
- Short Name:
- J/A+A/567/A69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first in-depth study of the kinematic properties and derive the structural parameters of NGC 4372 based on the fit of a Plummer profile and a rotating, physical model. We explore the link between internal rotation to different cluster properties and together with similar studies of more GCs, we put these in the context of globular cluster formation and evolution. We present radial velocities for 131 cluster member stars measured from high-resolution FLAMES/GIRAFFE observations. Their membership to the GC is additionally confirmed from precise metallicity estimates. Using this kinematic data set we build a velocity dispersion profile and a systemic rotation curve. Additionally, we obtain an elliptical number density profile of NGC 4372 based on optical images using a MCMC fitting algorithm. From this we derive the cluster's half-light radius and ellipticity as r_h_=3.4'+/-0.04' and e=0.08+/-0.01. Finally, we give a physical interpretation of the observed morphological and kinematic properties of this GC by fitting an axisymmetric, differentially rotating, dynamical model. Our results show that NGC 4372 has an unusually high ratio of rotation amplitude to velocity dispersion (1.2 vs. 4.5km/s) for its metallicity. This, however, puts it in line with two other exceptional, very metal-poor GCs - M 15 and NGC 4590. We also find a mild flattening of NGC 4372 in the direction of its rotation. Given its old age, this suggests that the flattening is indeed caused by the systemic rotation rather than tidal interactions with the Galaxy. Additionally, we estimate the dynamical mass of the GC M_dyn=2.0+/-0.5 x 10^5 M_Sun based on the dynamical model, which constrains the mass-to-light ratio of NGC 4372 between 1.4 and 2.3 M_Sun/L_Sun, representative of an old, purely stellar population.
- ID:
- ivo://CDS.VizieR/J/ApJ/623/897
- Title:
- Reddening and extinction at high galactic latitude
- Short Name:
- J/ApJ/623/897
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared (JHKL) photometry of 103 southern stars located behind translucent interstellar clouds at high Galactic latitude. Our data are combined with visual photometry and spectral type information from the literature in a detailed analysis of the wavelength dependence of interstellar extinction by dust in these high-latitude clouds. We investigate the shape of the near-infrared extinction curve and evaluate the total line-of-sight extinction (A_V_) and ratio of total-to-selective extinction (R_V_) in each line of sight.
- ID:
- ivo://CDS.VizieR/J/A+A/321/236
- Title:
- Reddening and fluxes of carbon stars
- Short Name:
- J/A+A/321/236
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This table contains our CV-classification (see Subsec. 3.3 in the paper) for 133 carbon variables and their colour excess E(B-V) as determined by the method described in Sec. 4.
- ID:
- ivo://CDS.VizieR/J/A+A/440/901
- Title:
- Reddening and metallicity of NGC 6752
- Short Name:
- J/A+A/440/901
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate reddenings for Globular Clusters could be obtained by comparing the colour-temperature obtained using temperatures from reddening-free indicator (H{alpha}), with that given by standard colour-temperature calibrations. The large multiplexing opportunity offered by FLAMES at VLT2 allowed us to obtain spectra centered on H{alpha} at a resolution of R=6000 and 5<S/N<50 for 120 stars near the turn-off of NGC 6752 with GIRAFFE from a single 1300 seconds exposure on June 24th, 2004.
- ID:
- ivo://CDS.VizieR/J/AJ/145/157
- Title:
- Reddening curve of IRAS 14026+4341
- Short Name:
- J/AJ/145/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A fraction of the heavily reddened quasars require a reddening curve that is even steeper than that of the Small Magellanic Cloud. In this paper, we thoroughly characterize the anomalously steep reddening law in quasars via an exceptional example observed in IRAS14026+4341. By comparing the observed spectrum to the quasar composite spectrum, we derive a reddening curve in the rest-frame wavelength range of 1200-10000{AA}. It has a steep rise at wavelengths shorter than 3000{AA}, but no significant reddening at longer wavelengths. The absence of dust reddening in the optical continuum is confirmed by the normal broad-line Balmer decrement (the H{alpha}/H{beta} ratio) in IRAS14026+4341. The anomalous reddening curve can be satisfactorily reproduced with a dust model containing silicate grains in a power-law size distribution, dn(a)/da{prop.to}a^-1.4^, truncated at a maximum size of a_max_=70nm. The unusual size distribution may be caused by the destruction of large "stardust" grains by quasar activities or a different dust formation mechanism (i.e., the in situ formation of dust grains in quasar outflows). It is also possible that the analogies of the dust grains observed near the Galactic center are responsible for the steep reddening curve. In addition, we find that IRAS14026+4341 is a weak emission-line quasar (i.e., PHL1811 analogies) with heavy dust reddening and blueshifted broad absorption lines.
