Astronomy Theory, Observations & Methods

New distance estimates to Pulsating RR Lyrae Star DM And.

Adanna Frazier — 2021-11-04

This is a study of the photometric data of the RR Lyrae star, DM And, in the B, V, sdssi, and sdss-z filters. The light curve shapes and estimated period 0.631± 0.011d in the B-filter, 0.631± 0.012d in the V-filter, 0.631± 0.011d in the sdss-i filter, 0.631± 0.011d in the sdss-z filter, and an average period of 0.6301 0.011d represent that of a typical RRab type RR Lyrae star. DM And’s magnitude is 12.175± 0.010 in B, 11.70± 0.010 in V, 11.60± 0.03 in sdss-i and 11.475± 0.046 in sdss-z, with an average magnitude of 11.738± 0.024. DM And has a measured distance averaged over all filters of 1647± 42 pc, 1558± 46 pc in V, 1728± 77 pc in sdss-i, and 1653± 95 pc in sdss-z. These results are comparable to GAIA’s measured distance of 1572± 157 pc.

AW Mic: The RR Lyrae That Wasn’t

Gerri Bernard — 2021-08-01

AW Mic is a neglected star that has previously been categorised as an ‘unusual’ RRc variable. This paper makes use of new and archival observations of AW Mic to establish that this star is no longer varying in magnitude and should no longer be classified as an RR Lyrae variable. Mid magnitudes of 9.171 ± 0.026 and 9.001 ± 0.014 are reported for this star in the B- and V-bands, respectively.

Observations of U Leporis

Larson Pavey — 2021-08-01

U Leporis (U Lep) is a pulsating variable that demonstrates periodic variation in apparent magnitude consistent with RR Lyrae variable stars. Images were acquired by the 0.4 meter telescopes of the Las Cumbres Observatory Global Telescope network in the visible (B, V) and near infrared (i and z) over a two week period in October 2019 and analyzed using Astrosource. Light curves were constructed for each of the four bandpasses, yielding a mean period of 0.581±0.011 days. The middle apparent magnitudes determined for the B, V, i, and z filters were 10.75, 10.55, 10.30, and 10.35 respectively. Color excess E(B-V) was determined by two methods (1) minimizing variance in the calculated distances for the V, i, and z bands (0.065) and (2) galactic dust (0.029), with the second method preferred. Distances in parsecs to U Lep were determined for the V (968±38), i (932±33), and z (951±38) filters. The average distance of 950±21 compares favorably to that obtained by Klein (977±8 pc) and less so to Gaia DR2 (1076±36 pc).

Original Research By Young Twinkle Students (ORBYTS): Ephemeris Refinement of Transiting Exoplanets III

Billy Edwards — 2021-08-01

We report photometric follow-up observations of thirteen exoplanets (HATS-1 b, HATS-2 b, HATS-3 b, HAT-P-18 b, HAT-P-27 b, HAT-P-30 b, HAT-P-55 b, KELT-4A b, WASP-25 b, WASP-42 b, WASP-57 b, WASP-61 b and WASP-123 b), as part of the Original Research By Young Twinkle Students (ORBYTS) programme. All these planets are potentially viable targets for atmospheric characterisation and our data, which were taken using the LCOGT network of ground-based telescopes, will be combined with observations from other users of ExoClock to ensure that the transit times of these planets continue to be well-known, far into the future.

Using Period-Luminosity-Metallicity relations to Calculate Distance for the RR Lyrae Star, EZ Lyr

Kaitlyn Kidwell — 2021-08-01

Reliable methods to measure intergalactic distances are a valuable resource in the field of astronomy. Periodic variables stars, such as RR Lyraes, can be used as standard candles to determine the distance to the stellar structures where they are located. For this reason, many different student groups observed and analyzed RR Lyrae stars through a research course offered by Our Solar Siblings, and the focus of this particular study was the star EZ Lyr. Images of EZ Lyr were taken by Las Cumbres Observatory and processed using tools provided for the research course. Light curves were produced in B, V, sdss-i and sdss-z filters that were analyzed to determine the star’s period and luminosity. The period-luminosity-metallicity relations described in Caceres and Catelan (2008) were used to calculate the distance to EZ Lyr in each filter. The final distance measurement, 1406±32pc was slightly closer (~100 pc) compared to results from the GAIA satellite.

ExoSelect and ExoRequest: Targets and Resources for efficiently observing Exoplanets

Saeed Salimpour — 2021-08-01

In the past decade, exoplanet science has exploded, driven by discoveries using observations from both space-based and ground-based telescopes. Large amounts of data, coupled with technological advances and easy access to robotic telescopes, have allowed the general public and students to become vital contributors to the field. These developments have also provided fertile ground in the context of science education, by enabling exoplanet science to be taken into classrooms as an authentic scientific inquiry, echoing the notions of Science-as-Practice. This paper introduces technical infrastructure that enables beginners and students to quickly pick exoplanet targets and schedule an observation. It also provides a list of the “best” exoplanets to try and observe by month of the year (related to Right Ascension) and latitude (related to Declination).

Evidence for V363 Cas as a First Overtone Anomalous Cepheid

Kafal Shawn — 2021-11-04

V363 Cassiopeiae was observed through 51 acquisitions of each of V, B, i and z filters, during a 15 day observation window. From the observations, folded light curves were generated using a PDM technique. It was my objective to provide further evidence for this star’s reclassification as a first overtone Anomalous Cepheid, as some past papers have proposed (Fernley, 1998). Based on our light curve characteristics (shape, and period), V363 Cas appeared to favor the anomalous Cepheid class over any RR Lyrae class. My observed period of 0.545 days is higher than the typical range of periods for RRd Lyrae, reported between 0.25 and 0.49 days (Soszynski et al., 2008). The RRab type Lyrae, as some have imposed on V363 Cas (Kholopov et al., 1985), was ruled out due to the evidence for overtone pulsation by Hajdu et al. (Hajdu, Jurcsik, et al., 2009) and Fernley (Fernley, 1998). Finally, a rough distance comparison to GAIA, using Nemec’s 1994 P-L-[Fe/H] for Anomalous Cepheids (Nemec, Nemec, & Lutz, 1994), estimated the distance of V363 Cas to be closer to the distance estimated by GAIA than estimates made with RRd class equations.