scholarly journals 1318 new variable stars in a 0.25 square degree region of the Galactic plane

2010 ◽  
Vol 519 ◽  
pp. A12 ◽  
Author(s):  
V. R. Miller ◽  
M. D. Albrow ◽  
C. Afonso ◽  
Th. Henning
2004 ◽  
Vol 202 ◽  
pp. 69-71
Author(s):  
Douglas A. Caldwell ◽  
W. J. Borucki ◽  
J. M. Jenkins ◽  
D. G. Koch ◽  
L. Webster ◽  
...  

The NASA Ames Research Center's Vulcan photometer is being used in a search for close–in giant extrasolar planets. With our current data reduction system we achieve 0.2–0.8% hour–to–hour relative photometric precision on ∽ 6000 stars brighter than 13th magnitude. Three Galactic-plane fields have so far yielded hundreds of variable stars, including ∽ 50 eclipsing or interacting binaries per field. Several candidate detections have been followed up with radial velocity observations. High-resolution spectroscopy revealed many of the strongest candidates to be grazing eclipsing binaries.


2019 ◽  
Vol 14 (S353) ◽  
pp. 1-5
Author(s):  
Pawel Pietrukowicz

AbstractClassical Cepheids and RR Lyrae-type variable stars are widely-used tracers of young (< 300 Myr) and old (> 10 Gyr) stellar populations, respectively. These stars also serve as distance indicators allowing for Galactic structure studies. Robust detection of pulsating variables requires precise and relatively frequent observations over several years. Recently, the OGLE survey has discovered nearly 1,300 new genuine classical Cepheids and 15,000 RR Lyrae stars along the southern Galactic plane. Here, we present the picture of the Milky Way’s thin disk drawn with the Cepheids and the view of the Galactic old population that emerges from the set of known RR Lyrae stars.


Author(s):  
Kenshi Yanagisawa ◽  
Yasuhiro Shimizu ◽  
Kiichi Okita ◽  
Daisuke Kuroda ◽  
Hironori Tsutsui ◽  
...  

Abstract We report on the development of a wide-field near-infrared (0.9–2.5$\, \mu$m) camera built as a renewal of the existing classical Cassegrain 0.91 m telescope at Okayama Astrophysical Observatory. The optics system was replaced with fast hybrid optics (f/2.5) composed of forward Cassegrain optics and quasi-Schmidt optics, which results in an effective image circle of 52 mm diameter on the focal plane. The new camera, called the Okayama Astrophysical Observatory Wide-Field Camera (OAOWFC), has imaging capabilities in the $Y$, $J$, $H$, and $K_{\rm s}$ bands over a field of view of $0.^{\!\!\!\circ }47 \times 0.^{\!\!\!\circ }47$ with a HAWAII-1 HgCdTe PACE focal plane array. The primary purpose of OAOWFC is to search for variability in the Galactic plane in the $K_{\rm s}$ band and to promptly follow up transients. We have demonstrated a photometric repeatability of 2% in the densest field in the northern Galactic plane and successfully discovered previously unreported variable stars. The observations of OAOWFC are fully autonomous, and we started scientific operations in 2015 April.


2021 ◽  
Vol 5 (10) ◽  
pp. 245
Author(s):  
Aleks Scholz ◽  
Ben Warwick ◽  
Thomas van Aalten

2021 ◽  
Vol 258 (1) ◽  
pp. 2
Author(s):  
Xiaolong Li ◽  
Fabio Ragosta ◽  
William I. Clarkson ◽  
Federica B. Bianco

Abstract Perhaps the most exciting promise of the Rubin Observatory Legacy Survey of Space and Time (LSST) is its capability to discover phenomena never before seen or predicted: true astrophysical novelties; but the ability of LSST to make these discoveries will depend on the survey strategy. Evaluating candidate strategies for true novelties is a challenge both practically and conceptually. Unlike traditional astrophysical tracers like supernovae or exoplanets, for anomalous objects, the template signal is by definition unknown. We approach this problem by assessing survey completeness in a phase space defined by object color and flux (and their evolution), and considering the volume explored by integrating metrics within this space with the observation depth, survey footprint, and stellar density. With these metrics, we explore recent simulations of the Rubin LSST observing strategy across the entire observed spatial footprint and in specific Local Volume regions: the Galactic Plane and Magellanic Clouds. Under our metrics, observing strategies with greater diversity of exposures and time gaps tend to be more sensitive to genuinely new transients, particularly over time-gap ranges left relatively unexplored by previous surveys. To assist the community, we have made all of the tools developed publicly available. While here we focus on transients, an extension of the scheme to include proper motions and the detection of associations or populations of interest will be communicated in Paper II of this series. This paper was written with the support of the Vera C. Rubin LSST Transients and Variable Stars and Stars, Milky Way, Local Volume Science Collaborations.


2017 ◽  
Vol 13 (S334) ◽  
pp. 335-336
Author(s):  
Noriyuki Matsunaga ◽  

AbstractWe have conducted a large-scale survey of variable stars in the northern Galactic plane, about 320 square degrees using Kiso Wide Field Camera attached to the 105-cm Schmidt telescope at Kiso observatory. In the KISOGP (KWFC Intensive Survey of the Galactic Plane), we collected 40–100 epoch I-band images between 2012 and 2017. In our survey region roughly 5 million stars exist down to the limiting magnitude of ~16.5 mag in I. In the initial data analysis, we detected a couple of thousands of variable stars including approximately 100 Cepheids and more than 700 Miras. More than 80 percents of them were not previously reported as variable stars, indicating that there are still many relatively bright variables to be found in the Galactic plane.


2018 ◽  
Vol 620 ◽  
pp. L9 ◽  
Author(s):  
G. Ramsay

Blue large-amplitude pulsators (BLAPs) are blue stars emitting high-amplitude (> 0.2 mag) pulsations on a timescale of a few tens of minutes. Recently discovered using OGLE data, they form a new class of variable star and have inspired a number of investigations searching for the origin of their pulsations. This short study presents the Gaia DR2 data for ten BLAPs for which parallax measurements are available. We have dereddened their colours using Gaia DR2 data from the stars in their immediate field and find that six show absolute magnitude and intrinsic colour consistent with expectations, whilst four stars have a less certain classification. This work highlights the extra information that Gaia DR2 data can provide to help classify those variable stars for which moderate-resolution optical spectra are not currently available. We also show how Gaia DR2 can make searches for BLAPs in wide-field high-cadence surveys more systematic and robust.


2020 ◽  
Vol 639 ◽  
pp. A81 ◽  
Author(s):  
S. Burssens ◽  
S. Simón-Díaz ◽  
D. M. Bowman ◽  
G. Holgado ◽  
M. Michielsen ◽  
...  

Context. The lack of high-precision long-term continuous photometric data for large samples of stars has impeded the large-scale exploration of pulsational variability in the OB star regime. As a result, the candidates for in-depth asteroseismic modelling have remained limited to a few dozen dwarfs. The TESS nominal space mission has surveyed the southern sky, including parts of the galactic plane, yielding continuous data across at least 27 d for hundreds of OB stars. Aims. We aim to couple TESS data in the southern sky with ground-based spectroscopy to study the variability in two dimensions, mass and evolution. We focus mainly on the presence of coherent pulsation modes that may or may not be present in the predicted theoretical instability domains and unravel all frequency behaviour in the amplitude spectra of the TESS data. Methods. We compose a sample of 98 OB-type stars observed by TESS in Sectors 1–13 and with available multi-epoch, high-resolution spectroscopy gathered by the IACOB and OWN surveys. We present the short-cadence 2 min light curves of dozens of OB-type stars, which have one or more spectra in the IACOB or OWN database. Based on these light curves and their Lomb–Scargle periodograms, we performed variability classification and frequency analysis. We placed the stars in the spectroscopic Hertzsprung–Russell diagram to interpret the variability in an evolutionary context. Results. We deduce the diverse origins of the mmag-level variability found in all of the 98 OB stars in the TESS data. We find among the sample several new variable stars, including three hybrid pulsators, three eclipsing binaries, high frequency modes in a Be star, and potential heat-driven pulsations in two Oe stars. Conclusions. We identify stars for which future asteroseismic modelling is possible, provided mode identification is achieved. By comparing the position of the variables to theoretical instability strips, we discuss the current shortcomings in non-adiabatic pulsation theory and the distribution of pulsators in the upper Hertzsprung–Russell diagram.


1967 ◽  
Vol 28 ◽  
pp. 207-244
Author(s):  
R. P. Kraft

(Ed. note:Encouraged by the success of the more informal approach in Christy's presentation, we tried an even more extreme experiment in this session, I-D. In essence, Kraft held the floor continuously all morning, and for the hour and a half afternoon session, serving as a combined Summary-Introductory speaker and a marathon-moderator of a running discussion on the line spectrum of cepheids. There was almost continuous interruption of his presentation; and most points raised from the floor were followed through in detail, no matter how digressive to the main presentation. This approach turned out to be much too extreme. It is wearing on the speaker, and the other members of the symposium feel more like an audience and less like participants in a dissective discussion. Because Kraft presented a compendious collection of empirical information, and, based on it, an exceedingly novel series of suggestions on the cepheid problem, these defects were probably aggravated by the first and alleviated by the second. I am much indebted to Kraft for working with me on a preliminary editing, to try to delete the side-excursions and to retain coherence about the main points. As usual, however, all responsibility for defects in final editing is wholly my own.)


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