- ID:
- ivo://CDS.VizieR/J/ApJ/679/1490
- Title:
- Photometry and Velocity of 3 {zeta} Aur binaries
- Short Name:
- J/ApJ/679/1490
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived new orbits for {zeta} Aur, 32 Cyg, and 31 Cyg with observations from the Tennessee State University (TSU) Automatic Spectroscopic Telescope, and used them to identify nonorbital velocities of the cool supergiant components of these systems. Our concurrent photometry detected the nonradial pulsations driven by tides (ellipsoidal variation) in both {zeta} Aur and 32 Cyg, at a level and phasing roughly consistent with simple theory to first order, although they seem to require moderately large gravity darkening. We point out two fundamental questions in the interpretation of these stars: (1) whether it is appropriate to model the surface brightness as gravity darkening and (2) whether much of the nonorbital velocity structure may actually represent changes in the convective flows in the stars' atmospheres.
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- ID:
- ivo://CDS.VizieR/J/ApJ/903/31
- Title:
- Photometry AT 2018hyz with Swift XRT, UVOT and Swope
- Short Name:
- J/ApJ/903/31
- Date:
- 11 Mar 2022 14:12:05
- Publisher:
- CDS
- Description:
- We present the multiwavelength analysis of the tidal disruption event (TDE) AT2018hyz (ASASSN-18zj). From follow-up optical spectroscopy, we detect the first unambiguous case of resolved double-peaked Balmer emission in a TDE. The distinct line profile can be well-modeled by a low eccentricity (e~0.1) accretion disk extending out to ~100Rp and a Gaussian component originating from non-disk clouds, though a bipolar outflow origin cannot be completely ruled out. Our analysis indicates that in AT2018hyz, disk formation took place promptly after the most-bound debris returned to pericenter, which we estimate to be roughly tens of days before the first detection. Redistribution of angular momentum and mass transport, possibly through shocks, must occur on the observed timescale of about a month to create the large H{alpha}-emitting disk that comprises <~5% of the initial stellar mass. With these new insights from AT2018hyz, we infer that circularization is efficient in at least some, if not all optically bright, X-ray faint TDEs. In these efficiently circularized TDEs, the detection of double-peaked emission depends on the disk inclination angle and the relative strength of the disk contribution to the non-disk component, possibly explaining the diversity seen in the current sample.
- ID:
- ivo://CDS.VizieR/J/ApJS/198/1
- Title:
- Photometry catalogs for the Lockman Hole
- Short Name:
- J/ApJS/198/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present broadband photometry and photometric redshifts for 187611 sources located in ~0.5deg^2^ in the Lockman Hole area. The catalog includes 388 X-ray-detected sources identified with the very deep XMM-Newton observations available for an area of 0.2deg^2^. The source detection was performed on the Rc-, z'-, and B-band images and the available photometry is spanning from the far-ultraviolet to the mid-infrared, reaching in the best-case scenario 21 bands. Astrometry corrections and photometric cross-calibrations over the entire data set allowed the computation of accurate photometric redshifts. Special treatment is undertaken for the X-ray sources, the majority of which are active galactic nuclei (AGNs). For normal galaxies, comparing the photometric redshifts to the 253 available spectroscopic redshifts, we achieve an accuracy of {sigma}_{Delta}z/(1+z)_=0.036, with 12.6% outliers. For the X-ray-detected sources, compared to 115 spectroscopic redshifts, the accuracy is {sigma}_{Delta}z/(1+z)_=0.069, with 18.3% outliers, where the outliers are defined as sources with |z_phot_-z_spec_|>0.15x(1+z_spec_).
- ID:
- ivo://CDS.VizieR/J/ApJ/742/113
- Title:
- Photometry during the 2010 eruption of U Sco
- Short Name:
- J/ApJ/742/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The eruption of the recurrent nova U Scorpii on 2010 January 28 is now the all-time best observed nova event. We report 36776 magnitudes throughout its 67 day eruption, for an average of one measure every 2.6 minutes. This unique and unprecedented coverage is the first time that a nova has had any substantial amount of fast photometry. With this, two new phenomena have been discovered: the fast flares in the early light curve seen from days 9-15 (which have no proposed explanation) and the optical dips seen out of eclipse from days 41-61 (likely caused by raised rims of the accretion disk occulting the bright inner regions of the disk as seen over specific orbital phases). The expanding shell and wind cleared enough from days 12-15 so that the inner binary system became visible, resulting in the sudden onset of eclipses and the turn-on of the supersoft X-ray source. On day 15, a strong asymmetry in the out-of-eclipse light points to the existence of the accretion stream. The normal optical flickering restarts on day 24.5. For days 15-26, eclipse mapping shows that the optical source is spherically symmetric with a radius of 4.1R_{sun}_. For days 26-41, the optical light is coming from a rim-bright disk of radius 3.4R_{sun}_. For days 41-67, the optical source is a center-bright disk of radius 2.2R_{sun}_. Throughout the eruption, the colors remain essentially constant. We present 12 eclipse times during eruption plus five just after the eruption.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1825
- Title:
- Photometry identification of cool white dwarfs
- Short Name:
- J/AJ/128/1825
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the use of a narrowband DDO51 filter for photometric identification of cool white dwarfs. We report photometric observations of 30 known cool white dwarfs with temperatures ranging from 10,000K down to very cool temperatures (<=3500K). Follow-up spectroscopic observations of a sample of objects selected using this filter and our photometric observations show that DDO51 filter photometry can help select cool white dwarf candidates for follow-up multiobject spectroscopy by rejecting 65% of main-sequence stars with the same broadband colors as the cool white dwarfs. This technique is not selective enough to efficiently feed single-object spectrographs. We present the white dwarf cooling sequence using this filter. Our observations show that very cool white dwarfs form a sequence in the r-DDO versus r-z color-color diagram and demonstrate that significant improvements are needed in white dwarf model atmospheres.
- ID:
- ivo://CDS.VizieR/J/A+A/389/439
- Title:
- Photometry in field of RX J004404.8+411820
- Short Name:
- J/A+A/389/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We propose the first association of an optical counterpart with a luminous supersoft X-ray source in M31, RX J0044.0+4118, observed with ROSAT in July 1991. The PSPC position is at 1.644 angular distance from a candidate nova in outburst in September of 1990. This is interesting because the incidence of classical novae among supersoft X-ray sources is an open question. The proposed optical counterpart was measured at R~=17.7 in September of 1990, and it had faded to R>19.2 when it was observed again after 70 days. The light curve was too sparsely monitored for definite conclusions on the speed class of the nova. No other variable objects with V<23.5 were found in the ROSAT spatial error box. We evaluate that the probability that a classical or recurrent nova was in outburst in the ROSAT error box in the few years preceding the observation is very small, so the proposed identification is meaningful. We also show evidence that the associated supersoft X-ray source turned off in the third year after the outburst.
- ID:
- ivo://CDS.VizieR/J/PAZh/36/16
- Title:
- Photometry in 6 galactic open star clusters
- Short Name:
- J/PAZh/36/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of our BVRcIc CCD photometry for six Galactic open star clusters toward the Perseus spiral arm performed at the Special Astrophysical Observatory of the Russian Academy of Sciences.
- ID:
- ivo://CDS.VizieR/J/AJ/148/27
- Title:
- Photometry in globular clusters. I. NGC 1851
- Short Name:
- J/AJ/148/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of multiple populations (MPs) in globular clusters (GCs) has become a forefront area of research in astronomy. Multiple red giant branches (RGBs), subgiant branches (SGBs), and even main sequences (MSs) have now been observed photometrically in many GCs, while broad abundance distributions of certain elements have been detected spectroscopically in most, if not all, GCs. UV photometry has been crucial in discovering and analyzing these MPs, but the Johnson U and the Stromgren and Sloan u filters that have generally been used are relatively inefficient and very sensitive to reddening and atmospheric extinction. In contrast, the Washington C filter is much broader and redder than these competing UV filters, making it far more efficient at detecting MPs and much less sensitive to reddening and extinction. Here, we investigate the use of the Washington system to uncover MPs using only a 1 m telescope. Our analysis of the well-studied GC NGC 1851 finds that the C filter is both very efficient and effective at detecting its previously discovered MPs in the RGB and SGB. Remarkably, we have also detected an intrinsically broad MS best characterized by two distinct but heavily overlapping populations that cannot be explained by binaries, field stars, or photometric errors. The MS distribution is in very good agreement with that seen on the RGB, with ~30% of the stars belonging to the second population. There is also evidence for two sequences in the red horizontal branch, but this appears to be unrelated to the MPs in this cluster. Neither of these latter phenomena have been observed previously in this cluster. The redder MS stars are also more centrally concentrated than the blue MS. This is the first time MPs in an MS have been discovered from the ground, and using only a 1 m telescope. The Washington system thus proves to be a very powerful tool for investigating MPs, and holds particular promise for extragalactic objects where photons are limited.
- ID:
- ivo://CDS.VizieR/J/PASP/105/78
- Title:
- Photometry in open cluster NGC 5822
- Short Name:
- J/PASP/105/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study presents photoelectric photometry of stars in NGC 5822 on the UBVR and DDO systems. The BV data are employed to calibrate a photographic survey of the cluster, while UBV and DDO data are used to constrain the cluster reddening and metallicity. Taken in conjunction with previous photometric analysis, it is found that the cluster has a reddening of 0.15+/-0.015(pe) as defined for the stars at the turnoff, and a metallicity relative to the sun of -0.15+/-0.05(pe).
- ID:
- ivo://CDS.VizieR/J/AJ/127/660
- Title:
- Photometry in southern tail of the Antennae
- Short Name:
- J/AJ/127/660
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Hubble Space Telescope and Wide Field Planetary Camera 2 to image the putative tidal dwarf galaxy located at the tip of the Southern tidal tail of NGC 4038/4039, the Antennae. We resolve individual stars and identify two stellar populations. Hundreds of massive stars are present, concentrated into tight OB associations on scales of 200pc, with ages ranging from 2 to 100Myr. An older stellar population is distributed roughly following the outer contours of the neutral hydrogen in the tidal tail; we associate these stars with material ejected from the outer disks of the two spirals. The older stellar population has a red giant branch tip at I=26.5+/-0.2 from which we derive a distance modulus (m-M)_0_=30.7+/-0.25. The implied distance of 13.8+/-1.7Mpc is significantly smaller than commonly quoted distances for NGC 4038/4039. In contrast to the previously studied core of the merger, we find no superstar clusters (SSCs).
