A hidden population of massive white dwarfs: two spotted K+WD binaries

The identification and characterization of massive ($\gtrsim 0.8~M_\odot$) white dwarfs is challenging in part due to their low luminosity. Here we present two candidate single-lined spectroscopic binaries, Gaia DR3 4014708864481651840 and 5811237403155163520, with K-dwarf primaries and optically dark companions. Both have orbital periods of $P\sim 0.45$ days and show rotational variability, ellipsoidal modulations, and high-amplitude radial velocity variations. Using light curves from the Transiting Exoplanet Survey Satellite (TESS), radial velocities from ground-based spectrographs, and spectral energy distributions, we characterize these binaries to describe the nature of the unseen companion. We find that both systems are consistent with a massive white dwarf companion. Unlike simple ellipsoidal variables, star spots cause the light curve morphology to change between TESS sectors. We attempt to constrain the orbital inclination using PHOEBE binary light curve models, but degeneracies in the light curves of spotted stars prevent a precise determination. Finally, we search for similar objects using Gaia DR3 and TESS, and comment on these systems in the context of recently claimed compact object binaries.Comment: 17 pages, 15 figures. Submitted to MNRA

The Value-Added Catalog of ASAS-SN Eclipsing Binaries: Parameters of Thirty Thousand Detached Systems

Detached eclipsing binaries are a fundamental tool for measuring the physical parameters of stars that are effectively evolving in isolation. Starting from more than 40,000 eclipsing binary candidates identified by the All-Sky Automated Survey for Supernovae (ASAS-SN), we use PHOEBE to determine the sum of the fractional radii, the ratio of effective temperatures, the inclinations, and the eccentricities for 35,464 systems. We visually inspect all the light curve models to verify the model fits and examine the TESS light curves, when available, to select systems with evidence for additional physics, such as spots, mass transfer, and hierarchical triples. We examine the distributions of the eclipsing binary model parameters and the orbital parameters. We identify two groups in the sum of the fractional radii and effective temperature ratio parameter space that may distinguish systems approaching the semidetached limit. Combining Gaia EDR3 with extinction estimates from 3-dimensional dust maps, we examine the properties of the systems as a function of their absolute magnitude and evolutionary state. Finally, we present light curves of selected eclipsing binaries that may be of interest for follow-up studies.Comment: 24 pages, 26 figures. Submitted to MNRA

Utility of WIfI foot assessment tool in a Sri Lankan setting; an initial experience

Introduction: Potential for limb salvage and wound healing in a lower limb ulcer depends on degreeof ischemia, wound grade and superadded foot infection.Objectives: Our objective was to assess the feasibility of applying WIfI classification system to stratifypatients presenting with limb ulceration according to risk of undergoing amputation and benefit ofrevascularization.Methods: Fifty four consecutive patients with ulcerated limbs presenting over two months to theUniversity unit at the National Hospital were staged according to the Society for Vascular Surgery(SVS)Wound, Ischemia, and Foot Infection (WIfI) classification system.Results: The median age was 64 (39-93), and 42 (79%) patients were males. Diabetes (87%),hypertension (53%), ischemic heart disease (14%), cerebrovascular disease (13%), chronic renal disease(13%) were identified risk factors. Smoking was reported among 35%. Median Anterior TibialArtery(ATA), Posterior Tibial Artery(PTA), Toe pressures, Ankle Brachial Index, Pole test values ofthe affected side lower limbs were 114.5mmHg, 107.5mmHg, 41mmHg, 0.87 and 85cm respectively.Values for the contralateral limb were 140mmHg, 120mmHg, 74mmHg, 1.0 and 85cm respectively.84% of ATA and 90 % of PTA pulses were not palpable on the affected side. Grades of ischemia were;none (23.3%), mild (27.9%), moderate (18.6%), severe (30.2%), grades of infection were none (20.9%),mild (37.2%), moderate (39.5%), severe (2.3%), and wound grades were 0(0%), 1(20%.9), 2(39.5%),3(39.5%). Estimated risk of amputation were high (65.1%), moderate (11.6%), low (11.6%), very low(11.6%) and estimated benefit of revascularization were high (46.5%) moderate (23.3%), low (7.0%),very low (23.3%).Conclusions: Application of WIfI system was useful to prioritize patients with eminent limb loss forurgent intervention. Toe pressure assessment for diabetic foot ulcer stratification should become acommon practice

Expectations versus reality in chronic venous ulceration; a quality of life assessment study

Introduction: Chronic venous ulceration is a common problem worldwide with a significant effect onQuality of Life (QoL).Objectives: Our objective was to assess Sri Lankan patients’ perspective with regard to this scenario.Methods: We involved 141 consenting patients presenting to the OPD, National Hospital with a venousulcer lasting one month or more. Data was collected using an interviewer administered questionnaire, aclinical interview and a lower limb duplex scan. Short form 36 questionnaire was used for QoLassessment.Results: The majority were elderly (median age 53 years) men (n=9[69.5%]). Fifty four (38.3%) wereunemployed at the time of the study and 28 (19.9%) directly attributed the ulcer as the cause forunemployment. Median duration of ulcer was 10[1-360] months and mean Venous Clinical SeverityScore (VCSS) was 13.85(4-24). Family history (44[31.2%]), previous limb trauma or non-venoussurgery (24[17.0%]), smoking among men (57 [58.2%]) and history of pregnancy among females(34[79.1%]) were identified as risk factors. Role limitation due to physical health (28.4[SD 42.8]) androle emotional problems (40.9 [SD 46.7]) had a mean SF 36 score below 50. Factors such as pain,duration of ulcer, older age and higher BMI significantly affected many domains of QoL (p<0.05). Sixtysix (46.8%) patients continue to have ulcers despite having had surgical treatment for varicose veins.Conclusions: Venous ulcers have a considerable impact on the quality of life in Sri Lankan patientswith venous ulcer. The need for providing preventive and rapid healing methods together with socialsupport must be emphasized

ASAS-SN Sky Patrol V2.0

The All-Sky Automated Survey for Supernovae (ASAS-SN) began observing in late-2011 and has been imaging the entire sky with nightly cadence since late 2017. A core goal of ASAS-SN is to release as much useful data as possible to the community. Working towards this goal, in 2017 the first ASAS-SN Sky Patrol was established as a tool for the community to obtain light curves from our data with no preselection of targets. Then, in 2020 we released static V-band photometry from 2013--2018 for 61 million sources. Here we describe the next generation ASAS-SN Sky Patrol, Version 2.0, which represents a major progression of this effort. Sky Patrol 2.0 provides continuously updated light curves for 111 million targets derived from numerous external catalogs of stars, galaxies, and solar system objects. We are generally able to serve photometry data within an hour of observation. Moreover, with a novel database architecture, the catalogs and light curves can be queried at unparalleled speed, returning thousands of light curves within seconds. Light curves can be accessed through a web interface (http://asas-sn.ifa.hawaii.edu/skypatrol/) or a Python client (https://asas-sn.ifa.hawaii.edu/documentation). The Python client can be used to retrieve up to 1 million light curves, generally limited only by bandwidth. This paper gives an updated overview of our survey, introduces the new Sky Patrol, and describes its system architecture. These results provide significant new capabilities to the community for pursuing multi-messenger and time-domain astronomy.Comment: Light curves can be accessed through a web interface http://asas-sn.ifa.hawaii.edu/skypatrol, or a Python client at http://asas-sn.ifa.hawaii.edu/documentatio

The ASAS-SN Catalog of Variable Stars III: Variables in the Southern TESS Continuous Viewing Zone

The All-Sky Automated Survey for Supernovae (ASAS-SN) provides long baseline (${\sim}4$ yrs) light curves for sources brighter than V$\lesssim17$ mag across the whole sky. The Transiting Exoplanet Survey Satellite (TESS) has started to produce high-quality light curves with a baseline of at least 27 days, eventually for most of the sky. The combination of ASAS-SN and TESS light curves probes both long and short term variability in great detail, especially towards the TESS continuous viewing zones (CVZ) at the ecliptic poles. We have produced ${\sim}1.3$ million V-band light curves covering a total of ${\sim}1000 \, \rm deg^2$ towards the southern TESS CVZ and have systematically searched these sources for variability. We have identified ${\sim} 11,700$ variables, including ${\sim} 7,000$ new discoveries. The light curves and characteristics of the variables are all available through the ASAS-SN variable stars database (https://asas-sn.osu.edu/variables). We also introduce an online resource to obtain pre-computed ASAS-SN V-band light curves (https://asas-sn.osu.edu/photometry) starting with the light curves of the ${\sim}1.3$ million sources studied in this work. This effort will be extended to provide ASAS-SN light curves for ${\sim}50\;$million sources over the entire sky.Comment: 13 pages, 12 figures. Submitted to MNRA