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591. New variables in Sagittarius
ID:
ivo://CDS.VizieR/J/A+AS/123/507
Title:
New variables in Sagittarius
Short Name:
J/A+AS/123/507
Date:
21 Oct 2021
Publisher:
CDS
Description:
For the coordinates and identification charts of the variables discovered in the other parts of the surveyed region, see references in the publication. A compilation of all the (~4000) variables discovered in the entire 100 square-degree surveyed region in the course of this programme, is in preparation and will be available at CDS in electronic form.
592. New variable stars and eclipsing binaries
ID:
ivo://CDS.VizieR/J/PASP/131/G5001
Title:
New variable stars and eclipsing binaries
Short Name:
J/PASP/131/G5001
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Evryscope is a telescope array designed to open a new parameter space in optical astronomy, detecting short-timescale events across extremely large sky areas simultaneously. The system consists of a 780 MPix 22-camera array with an 8150 sq. deg. field of view, 13'' per pixel sampling, and the ability to detect objects down to m_g'_~=16 in each 2-minute dark-sky exposure. The Evryscope, covering 18400 sq. deg. with hours of high-cadence exposure time each night, is designed to find the rare events that require all-sky monitoring, including transiting exoplanets around exotic stars like white dwarfs and hot subdwarfs, stellar activity of all types within our galaxy, nearby supernovae, and other transient events such as gamma-ray bursts and gravitational-wave electromagnetic counterparts. The system averages 5000 images per night with ~300000 sources per image, and to date has taken over 3.0M images, totaling 250 TB of raw data. The resulting light curve database has light curves for 9.3M targets, averaging 32600 epochs per target through 2018. This paper summarizes the hardware and performance of the Evryscope, including the lessons learned during telescope design, electronics design, a procedure for the precision polar alignment of mounts for Evryscope-like systems, robotic control and operations, and safety and performance-optimization systems. We measure the on-sky performance of the Evryscope, discuss its data analysis pipelines, and present some example variable star and eclipsing binary discoveries from the telescope. We also discuss new discoveries of very rare objects including two hot subdwarf eclipsing binaries with late M-dwarf secondaries (HW Vir systems), two white dwarf/hot subdwarf short-period binaries, and four hot subdwarf reflection binaries. We conclude with the status of our transit surveys, M-dwarf flare survey, and transient detection.
593. New variable stars in field SA9
ID:
ivo://CDS.VizieR/J/AZh/91/382
Title:
New variable stars in field SA9
Short Name:
J/AZh/91/382
Date:
21 Oct 2021
Publisher:
CDS
Description:
The new stage of work on digitizing the astronomical plates of the Sternberg Astronomical Institute's collection and searching for new variable stars using the digitized photographic plates includes a considerable improvement of the automated search techniques for objects with variable brightnesses. In particular, the technique for taking into account the non-linear response of the photographic light detector has been improved. Applying the improved techniques to 182 digitized images of a 10{deg}x10{deg} field centered at SA9, obtained from scanning photographic plates taken with the Sternberg Astronomical Institute 40-cm astrograph, has enabled the discover and study of 77 new variable stars (MDV 519-595). These include 3 Cepheids, 2 probableBY Draconis stars, 65 eclipsing binaries, 3RR Lyrae stars, 1 high-amplitude {delta} Scuti star (HADS), and 3 irregular variables. Special CCD observations have confirmed the presence of brightness variations in 7 of the 77 variables that were initially considered uncertain.
594. 1318 new variable stars in Galactic plane
ID:
ivo://CDS.VizieR/J/A+A/519/A12
Title:
1318 new variable stars in Galactic plane
Short Name:
J/A+A/519/A12
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have conducted a deep photometric survey of a 0.5deg*0.5deg area of the Galactic Plane using the WFI instrument on the 2.2-m ESO telescope on La Silla, Chile. The dataset comprises a total of 267 R-band images, 204 from a 16 day observation run in 2005, supplemented by 63 images from a six week period in 2002. Our reduction employed the new numerical kernel difference image analysis method as implemented in the pySIS3 code and resulted in more than 500000 lightcurves of stars down to a magnitude limit of R~24.5. A search for variable stars resulted in the detection of 1318 variables of different types. 1011 of these are eclipsing or contact binary stars. A number of the contact binaries have low mass-ratios and several of the detached binaries appear to have low-mass components. Three candidate contact binaries have periods at the known cut off including two with periods lower than any previously published. Also identified are 3 possible pre-main sequence detached eclipsing binaries.
595. New variable stars in 104 Her field
ID:
ivo://CDS.VizieR/J/other/RAA/18.92
Title:
New variable stars in 104 Her field
Short Name:
J/other/RAA/18.9
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using 172 plates taken with the 40-cm astrograph of the Sternberg Astronomical Institute (Lomonosov Moscow University) in 1976-1994 and digitized with a resolution of 2400 dpi, we discovered and studied 275 new variable stars. We present the list of our new variables with all necessary information concerning their brightness variations. As in our earlier studies, the new discoveries show a rather large number of high-amplitude Delta Scuti variables, predicting that many stars of this type remain not detected in the whole sky. We also performed automated classification of the newly discovered variable stars based on the Random Forest algorithm. The results of the automated classification were compared to traditional classification and showed that automated classification was possible even with noisy photographic data. However, further improvement of automated techniques is needed, which is especially important when considering the very large numbers of new discoveries expected from all-sky surveys.
596. New variable stars in 66 Oph field
ID:
ivo://CDS.VizieR/J/AZh/87/1087
Title:
New variable stars in 66 Oph field
Short Name:
J/AZh/87/1087
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the course of a program to digitize the astronomical plates of the Sternberg Astronomical Institute's plate stacks, we are developing algorithms for searching for new variable stars and studying them using digitized photographic plates. We have discovered and studied 480 new variable stars in a 10{deg}x10{deg} field of view centered on 66 Ophiuchi. The digitized plate negatives used are from the 40-cm astrograph, and are 30x30cm in size. These stars include three new Cepheids of the Galaxy's spherical component, 157 eclipsing binaries, 11 high-amplitude {delta} Scuti stars (HADSs), 144 RR Lyrae stars, 110 irregular variables (109 LB and one white star), and 55 semi-regular red variables.
597. New variable stars in Sgr B
ID:
ivo://CDS.VizieR/J/A+AS/49/715
Title:
New variable stars in Sgr B
Short Name:
J/A+AS/49/715
Date:
21 Oct 2021
Publisher:
CDS
Description:
621 new variable stars have been detected on plates obtained with the Schmidt telescopes of the Mount Palomar Observatory (1968) and of the European Southern Observatory (1976-1980). The astrometric measurements (ESO-CERN) and the photometrical ones (CDCA) which have followed the detection the variable stars (Observatoire de Lyon) have led to determine the parameters {alpha}, {delta}, l, b, R(Max), R(Min), {delta}m. So we notice that: - 379 variable stars have an amplitude of variation in magnitude between 0.5 and 2.0 (delm/N histogram). -The number of variable stars strongly decreases towards the great amplitudes. -The surface density of variable stars by square degree in this central galactic direction increases from 2 to 21 in the explored field of 5.5degx5.5deg size.
598. New variable stars towards Galactic Bulge
ID:
ivo://CDS.VizieR/J/MNRAS/482/3058
Title:
New variable stars towards Galactic Bulge
Short Name:
J/MNRAS/482/3058
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the detection of 3714 variable stars towards the Galactic bulge, including 2521 previously uncatalogued variables, using time-series photometry extracted from data obtained with the VIMOS imager at the Very Large Telescope. Observations of the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) field in the Galactic Bulge were taken over 2yr between March and October at a cadence of ~4d, enabling the detection of variables with periods up to ~100d. Many of these were already known, but we detected a significant number of new variables, including 11 Cepheids, a further 88 potential Cepheid candidates, and many contact binaries. Here we publish the catalogue of the new variables, containing coordinates, mean magnitudes as well as periods and classification; full light curves for these variables are also made available electronically.
599. New white dwarf pulsators for TESS
ID:
ivo://CDS.VizieR/J/MNRAS/478/2676
Title:
New white dwarf pulsators for TESS
Short Name:
J/MNRAS/478/2676
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of our survey searching for new white dwarf pulsators for observations by the TESS space telescope. We collected photometric time-series data on 14 white dwarf variable candidates at Konkoly Observatory, and found two new bright ZZ Ceti stars, namely EGGR 120 and WD 1310+583. We performed a Fourier analysis of the datasets. In the case of EGGR 120, which was observed on one night only, we found one significant frequency at 1332uHz with 2.3mmag amplitude. We successfully observed WD 1310+583 on eight nights, and determined 17 significant frequencies in the whole dataset. Seven of them seem to be independent pulsation modes between 634 and 2740uHz, and we performed preliminary asteroseismic investigations of the star utilizing six of these periods. We also identified three new light variables on the fields of white dwarf candidates: an eclipsing binary, a candidate delta Scuti/beta Cephei and a candidate W UMa-type star.
600. NGC1326A, 1425 and 4548 supergiants VI mags
ID:
ivo://CDS.VizieR/J/A+A/629/A3
Title:
NGC1326A, 1425 and 4548 supergiants VI mags
Short Name:
J/A+A/629/A3
Date:
21 Oct 2021
Publisher:
CDS
Description:
Studies on the massive star population in galaxies beyond the Local Group are the key to understand the link between their numbers and modes of star formation in different environments. We present the analysis of the massive star population of the galaxies NGC1326A, NGC 1425 and NGC 4548 using archival Hubble Space Telescope Wide Field Planetary Camera 2 images in the F555W and F814W filters. Through high precision point spread function fitting photometry for all sources in the three fields we identified 7640 candidate blue supergiants, 2314 candidate yellow supergiants, and 4270 candidate red supergiants. We provide an estimation the ratio of blue to red supergiants for each field as a function of galactocentric radius. Using Modules for Experiments in Stellar Astrophysics (MESA) at solar metallicity, we defined the luminosity function and estimated the star formation history of each galaxy. We carried out a variability search in the V and I filters using three variability indexes: the median absolute deviation, the interquartile range, and the inverse von-Neumann ratio. This analysis yielded 243 new variable candidates with absolute magnitudes ranging from M_V_=-4 to -10mag. We classified the variable stars based on their absolute magnitude and their position on the color-magnitude diagram using the MESA evolutionary tracks at solar metallicity. Our analysis yielded 8 candidate variable blue supergiants, 12 candidate variable yellow supergiants, 21 candidate variable red supergiants, and 4 candidate periodic variables.