Jaymie Matthews - Academia.edu (original) (raw)

Papers by Jaymie Matthews

The MOST (Microvariability and Oscillations of STars) astronomy mission has been chosen by the Ca... more The MOST (Microvariability and Oscillations of STars) astronomy mission has been chosen by the Canadian Space Agency\u27s Small Payloads Program to be Canada\u27s first space science microsatellite, and is currently planned for launch in late 2001. The MOST science team will use the MOST satellite to conduct long-duration stellar photometry observations in space. A major science goal is to set a lower limit on the age of several nearby metal-poor sub-dwarf stars, which may in turn allow a lower limit to be set on the age of the Universe. To make these measurements, MOST will incorporate a small (15 cm aperture), high-photometric-precision optical telescope to be developed by UBC. The MOST bus and ground stations are being developed by Dynacon and the University of Toronto, in collaboration with AMSAT Canada. Several of the bus subsystems are based on similar designs that have been flown on past AMSAT microsatellites. However, the MOST attitude control system is unusual for a microsa...

Monthly Notices of the Royal Astronomical Society, 2014

We carried out an extensive observational study of the Slowly Pulsating B (SPB) star, HD 25558. T... more We carried out an extensive observational study of the Slowly Pulsating B (SPB) star, HD 25558. The ≈ 2000 spectra obtained at different observatories, the ground-based and MOST satellite light curves revealed that this object is a double-lined spectroscopic binary with an orbital period of about 9 years. The observations do not allow the inference of an orbital solution. We determined the physical parameters of the components, and found that both lie within the SPB instability strip. Accordingly, both show line-profile variations due to stellar pulsations. Eleven independent frequencies were identified in the data. All the frequencies were attributed to one of the two components based on Pixel-by-pixel variability analysis of the line profiles. Spectroscopic and photometric mode identification was also performed for the frequencies of both stars. These results suggest that the inclination and rotation of the two components are rather different. The primary is a slow rotator with ≈ 6 d period, seen at ≈ 60 • inclination, while the secondary rotates fast with ≈ 1.2 d period, and is seen at ≈ 20 • inclination. Spectropolarimetric measurements revealed that the secondary component has a magnetic field with at least a few hundred Gauss strength, while no magnetic field can be detected in the primary.

Item consists of a digitized copy of an audio recording of a Vancouver Institute lecture given by... more Item consists of a digitized copy of an audio recording of a Vancouver Institute lecture given by Jaymie Matthews on December 2, 2000. Original audio recording available in the University Archives (UBC AT 2477).

Transiting exoplanet search and vetting codes described in Kunimoto et al. (2020), for use on lig... more Transiting exoplanet search and vetting codes described in Kunimoto et al. (2020), for use on light curve data to find multi-planet systems.

en Physique Searching for asteroids around another star

Differential UBV photometry of the southern helimu-strong star HD 96446 collectd in 1987 and 1990... more Differential UBV photometry of the southern helimu-strong star HD 96446 collectd in 1987 and 1990 at two observatories reveals periodic light variations with a V amplitude of ∼ 0.02 mag. The period which best satisfies both these data and the available magnetic observations is 0.85137 d. If these variations are due to rotational modulation in a magnetic oblique rotator, this would make HD 96446 one of the most rapidly rotating He-strong stars known, despite a v sin i ≤ 16 km/s.

The Journal of the Royal Astronomical Society of Canada. Royal Astronomical Society of Canada

The Astrophysical Journal, 2005

We report the detection of three discrete pulsation frequencies in the long-period variable subdw... more We report the detection of three discrete pulsation frequencies in the long-period variable subdwarf B star PG 0101+039 on the basis of $400 hr of MOST wide-band photometry. The periodicities uncovered lie at 7235, 5227, and 2650 s, respectively, and are associated with amplitudes between 0.03% and 0.06% of the mean brightness, lower than those measured in any other variable of this kind. We also find evidence for luminosity variations consistent with an ellipsoidal deformation of the subdwarf in the rotationally locked short-period binary system predicted from radial velocity measurements and evolutionary models. Our atmospheric modeling of two independent time-averaged optical spectra of PG 0101+039 yields T eA ' 28;300 K and log g ' 5:52, making it one of the hottest long-period variable subdwarf B stars known. The fact that we nevertheless detect brightness variations in the data is in conflict with predictions from current models, which place the theoretical blue edge for observable long-period instabilities at a temperature around 4000 K cooler than that of PG 0101+039.

The Advanced Maui …, 2006

The Near-Earth Object Surveillance Satellite (NEOSSat) is a joint project between Defence Researc... more The Near-Earth Object Surveillance Satellite (NEOSSat) is a joint project between Defence Research and Development Canada (DRDC) and the Canadian Space Agency (CSA). The NEOSSat project is developing the Canadian multi-mission micro-satellite bus to satisfy two concurrent ...

The Advanced Maui …, 2006

The Near-Earth Object Surveillance Satellite (NEOSSat) is a joint project between Defence Researc... more The Near-Earth Object Surveillance Satellite (NEOSSat) is a joint project between Defence Research and Development Canada (DRDC) and the Canadian Space Agency (CSA). The NEOSSat project is developing the Canadian multi-mission micro-satellite bus to satisfy two concurrent ...

Micro-and nano-satellites offer cost-effective platforms for space technology development and for... more Micro-and nano-satellites offer cost-effective platforms for space technology development and for targeted investigations in astronomy. The original 1999 CubeSat design, based on 1 litre-sized cubes, is now the standard '1U' prototyping architecture. The Canadian Space Agency was an early adopter of micro-satellites. The MOST (Microvariability and Oscillation of Stars) telescope was Canada's rst astronomy satellite. Launched in 2003, MOST offered a dedicated platform for asteroseismology that demonstrated the advantages of uninterrupted, long-duration staring observations well before the Kepler Mission adopted the same technique to discover thousands of extrasolar planets. MOST opened the astronomy time domain from space. The subsequent BRITE (BRIght Target Explorer) Constellation was the rst space astronomy mission to be carried out with nano-satellites, with Canada designing all and contributing two of the six 8U-sized satellites. Its greatest advantage was its ability to stay pointed on a wide eld (24 x 24 degres) monitoring up to 30 bright stellar targets for up to 6 months. Micro-satellite adoption remains slow in astronomy, mostly because of the need for large telescope apertures. However, as demonstrated by MOST and BRITE, time-domain photometry of bright objects, such as Milky Way stars and planetary systems, can be well-served by modest apertures. Improving detector technology is now opening micro-satellite platforms to fainter objects, multi-band photometry, non-optical wavelengths, and polarimetry. Canada is in a strong position to lead micro-satellite astronomy. Building small and cost-effective-but capable-space platforms will ensure that Canada stays at the forefront of space technology development. Focussing on a few key micro-satellite investigations will optimize the science impact of Canadian space astronomy. Early experience with Canadian micro-satellites also enhances Canadian expertise and HQP training for participation in larger international follow-on missions. The Canadian Space Agency currently operates two astronomy small-satellite missions, the Near Earth Object Surveillance Satellite (NEOSSat) and BRIght Target Explorer (BRITE) Constellation, and has two more missions under study: the Photometric Observations of Extrasolar Planets (POEP) and the Extrasolar Planet Polarimetry Explorer / Explorateur Polarimétrique des Planètes Extrasolaires (ÉPPÉ). NEOSSat's rst Guest Observer call for proposals in September 2019 was heavily (4.8:1) oversubscribed, re ecting intense astronomy interest. BRITE Constellation has already demonstrated to be one of Canada's highest-publication impact observatories. Both POEP and ÉPPÉ promise novel, science-enabling capabilities in space-based time-domain astronomy with applications well beyond their primary exoplanet-focussed goals. Reliable, dedicated funding to support research with the existing missions and to expand the astronomy small-satellite program will solidify Canada's trademark in space astronomy innovation.

The Astrophysical Journal Letters

The Astrophysical Journal

Since the onset of the 'space revolution' of high-precision high-cadence photometry, asteroseismo... more Since the onset of the 'space revolution' of high-precision high-cadence photometry, asteroseismology has been demonstrated as a powerful tool for informing Galactic archaeology investigations. The launch of the NASA TESS mission has enabled seismic-based inferences to go full sky-providing a clear advantage for large ensemble studies of the different Milky Way components. Here we demonstrate its potential for investigating the Galaxy by carrying out the first asteroseismic ensemble study of red giant stars observed by TESS. We use a sample of 25 stars for which we measure their global asteroseimic observables and estimate their fundamental stellar properties, such as radius, mass, and age. Significant improvements are seen in the uncertainties of our estimates when combining seismic observables from TESS with astrometric measurements from the Gaia mission compared to when the seismology and astrometry are applied separately. Specifically, when combined we show that stellar radii can be determined to a precision of a few percent, masses to 5-10% and ages to the 20% level. This is comparable to the precision typically obtained using end-of-mission Kepler data.

Symposium - International Astronomical Union

Warning to the unsuspecting reader: The editors of this volume have (bravely) asked me to “preser... more Warning to the unsuspecting reader: The editors of this volume have (bravely) asked me to “preserve the spirit” of my oral presentation. It is difficult to translate the stirring grandeur of a multi-coloured flashing bowtie into mere words and diagrams. Failing to evoke that grandeur, I have instead settled for occasionally capturing the tackiness of my battery-operated talk in Kyoto.

Monthly Notices of the Royal Astronomical Society

The magnetic chemically peculiar (Ap/CP2) star 21 Com has been extensively studied in the past, a... more The magnetic chemically peculiar (Ap/CP2) star 21 Com has been extensively studied in the past, albeit with widely differing and sometimes contradictory results, in particular concerning the occurrence of short-term variability between about 5 to 90 min. We have performed a new investigation of 21 Com using Microvariability and Oscillations of Star (MOST) satellite and high-cadence ground-based photometry, time series spectroscopy, and evolutionary and pulsational modelling. Our analysis confirms that 21 Com is a classical CP2 star showing increased abundances of, in particular, Cr and Sr. From spectroscopic analysis, we have derived T eff = 8 900 ± 200 K, log g = 3.9 ± 0.2, and υsin i = 63 ± 2 km s −1. Our modelling efforts suggest that 21 Com is a main sequence (MS) star seen equator-on with a mass of 2.29 ± 0.10 M and a radius of R = 2.6 ± 0.2 R. Our extensive photometric data confirm the existence of rotational light variability with a period of 2.052 19(2) d. However, no significant frequencies with a semi-amplitude exceeding 0.2 mmag were found in the frequency range from 5 to 399 d −1. Our RV data also do not indicate short-term variability. We calculated pulsational models assuming different metallicities and ages, which do not predict the occurrence of unstable modes. The star 18 Com, often employed as comparison star for 21 Com in the past, has been identified as a periodic variable (P = 1.416 45 d). While it is impossible to assess whether 21 Com has exhibited short-term variability in the past, the new observational data and several issues/inconsistencies identified in previous studies strongly suggest that 21 Com is neither a δ Scuti nor a roAp pulsator but a 'well-behaved' CP2 star exhibiting its trademark rotational variability.

The Astrophysical Journal, 2007

The MOST (Microvariability and Oscillations of STars) astronomy mission has been chosen by the Ca... more The MOST (Microvariability and Oscillations of STars) astronomy mission has been chosen by the Canadian Space Agency\u27s Small Payloads Program to be Canada\u27s first space science microsatellite, and is currently planned for launch in late 2001. The MOST science team will use the MOST satellite to conduct long-duration stellar photometry observations in space. A major science goal is to set a lower limit on the age of several nearby metal-poor sub-dwarf stars, which may in turn allow a lower limit to be set on the age of the Universe. To make these measurements, MOST will incorporate a small (15 cm aperture), high-photometric-precision optical telescope to be developed by UBC. The MOST bus and ground stations are being developed by Dynacon and the University of Toronto, in collaboration with AMSAT Canada. Several of the bus subsystems are based on similar designs that have been flown on past AMSAT microsatellites. However, the MOST attitude control system is unusual for a microsa...

Monthly Notices of the Royal Astronomical Society, 2014

We carried out an extensive observational study of the Slowly Pulsating B (SPB) star, HD 25558. T... more We carried out an extensive observational study of the Slowly Pulsating B (SPB) star, HD 25558. The ≈ 2000 spectra obtained at different observatories, the ground-based and MOST satellite light curves revealed that this object is a double-lined spectroscopic binary with an orbital period of about 9 years. The observations do not allow the inference of an orbital solution. We determined the physical parameters of the components, and found that both lie within the SPB instability strip. Accordingly, both show line-profile variations due to stellar pulsations. Eleven independent frequencies were identified in the data. All the frequencies were attributed to one of the two components based on Pixel-by-pixel variability analysis of the line profiles. Spectroscopic and photometric mode identification was also performed for the frequencies of both stars. These results suggest that the inclination and rotation of the two components are rather different. The primary is a slow rotator with ≈ 6 d period, seen at ≈ 60 • inclination, while the secondary rotates fast with ≈ 1.2 d period, and is seen at ≈ 20 • inclination. Spectropolarimetric measurements revealed that the secondary component has a magnetic field with at least a few hundred Gauss strength, while no magnetic field can be detected in the primary.

Item consists of a digitized copy of an audio recording of a Vancouver Institute lecture given by... more Item consists of a digitized copy of an audio recording of a Vancouver Institute lecture given by Jaymie Matthews on December 2, 2000. Original audio recording available in the University Archives (UBC AT 2477).

Transiting exoplanet search and vetting codes described in Kunimoto et al. (2020), for use on lig... more Transiting exoplanet search and vetting codes described in Kunimoto et al. (2020), for use on light curve data to find multi-planet systems.

en Physique Searching for asteroids around another star

Differential UBV photometry of the southern helimu-strong star HD 96446 collectd in 1987 and 1990... more Differential UBV photometry of the southern helimu-strong star HD 96446 collectd in 1987 and 1990 at two observatories reveals periodic light variations with a V amplitude of ∼ 0.02 mag. The period which best satisfies both these data and the available magnetic observations is 0.85137 d. If these variations are due to rotational modulation in a magnetic oblique rotator, this would make HD 96446 one of the most rapidly rotating He-strong stars known, despite a v sin i ≤ 16 km/s.

The Journal of the Royal Astronomical Society of Canada. Royal Astronomical Society of Canada

The Astrophysical Journal, 2005

We report the detection of three discrete pulsation frequencies in the long-period variable subdw... more We report the detection of three discrete pulsation frequencies in the long-period variable subdwarf B star PG 0101+039 on the basis of $400 hr of MOST wide-band photometry. The periodicities uncovered lie at 7235, 5227, and 2650 s, respectively, and are associated with amplitudes between 0.03% and 0.06% of the mean brightness, lower than those measured in any other variable of this kind. We also find evidence for luminosity variations consistent with an ellipsoidal deformation of the subdwarf in the rotationally locked short-period binary system predicted from radial velocity measurements and evolutionary models. Our atmospheric modeling of two independent time-averaged optical spectra of PG 0101+039 yields T eA ' 28;300 K and log g ' 5:52, making it one of the hottest long-period variable subdwarf B stars known. The fact that we nevertheless detect brightness variations in the data is in conflict with predictions from current models, which place the theoretical blue edge for observable long-period instabilities at a temperature around 4000 K cooler than that of PG 0101+039.

The Advanced Maui …, 2006

The Near-Earth Object Surveillance Satellite (NEOSSat) is a joint project between Defence Researc... more The Near-Earth Object Surveillance Satellite (NEOSSat) is a joint project between Defence Research and Development Canada (DRDC) and the Canadian Space Agency (CSA). The NEOSSat project is developing the Canadian multi-mission micro-satellite bus to satisfy two concurrent ...

The Advanced Maui …, 2006

The Near-Earth Object Surveillance Satellite (NEOSSat) is a joint project between Defence Researc... more The Near-Earth Object Surveillance Satellite (NEOSSat) is a joint project between Defence Research and Development Canada (DRDC) and the Canadian Space Agency (CSA). The NEOSSat project is developing the Canadian multi-mission micro-satellite bus to satisfy two concurrent ...

Micro-and nano-satellites offer cost-effective platforms for space technology development and for... more Micro-and nano-satellites offer cost-effective platforms for space technology development and for targeted investigations in astronomy. The original 1999 CubeSat design, based on 1 litre-sized cubes, is now the standard '1U' prototyping architecture. The Canadian Space Agency was an early adopter of micro-satellites. The MOST (Microvariability and Oscillation of Stars) telescope was Canada's rst astronomy satellite. Launched in 2003, MOST offered a dedicated platform for asteroseismology that demonstrated the advantages of uninterrupted, long-duration staring observations well before the Kepler Mission adopted the same technique to discover thousands of extrasolar planets. MOST opened the astronomy time domain from space. The subsequent BRITE (BRIght Target Explorer) Constellation was the rst space astronomy mission to be carried out with nano-satellites, with Canada designing all and contributing two of the six 8U-sized satellites. Its greatest advantage was its ability to stay pointed on a wide eld (24 x 24 degres) monitoring up to 30 bright stellar targets for up to 6 months. Micro-satellite adoption remains slow in astronomy, mostly because of the need for large telescope apertures. However, as demonstrated by MOST and BRITE, time-domain photometry of bright objects, such as Milky Way stars and planetary systems, can be well-served by modest apertures. Improving detector technology is now opening micro-satellite platforms to fainter objects, multi-band photometry, non-optical wavelengths, and polarimetry. Canada is in a strong position to lead micro-satellite astronomy. Building small and cost-effective-but capable-space platforms will ensure that Canada stays at the forefront of space technology development. Focussing on a few key micro-satellite investigations will optimize the science impact of Canadian space astronomy. Early experience with Canadian micro-satellites also enhances Canadian expertise and HQP training for participation in larger international follow-on missions. The Canadian Space Agency currently operates two astronomy small-satellite missions, the Near Earth Object Surveillance Satellite (NEOSSat) and BRIght Target Explorer (BRITE) Constellation, and has two more missions under study: the Photometric Observations of Extrasolar Planets (POEP) and the Extrasolar Planet Polarimetry Explorer / Explorateur Polarimétrique des Planètes Extrasolaires (ÉPPÉ). NEOSSat's rst Guest Observer call for proposals in September 2019 was heavily (4.8:1) oversubscribed, re ecting intense astronomy interest. BRITE Constellation has already demonstrated to be one of Canada's highest-publication impact observatories. Both POEP and ÉPPÉ promise novel, science-enabling capabilities in space-based time-domain astronomy with applications well beyond their primary exoplanet-focussed goals. Reliable, dedicated funding to support research with the existing missions and to expand the astronomy small-satellite program will solidify Canada's trademark in space astronomy innovation.

The Astrophysical Journal Letters

The Astrophysical Journal

Since the onset of the 'space revolution' of high-precision high-cadence photometry, asteroseismo... more Since the onset of the 'space revolution' of high-precision high-cadence photometry, asteroseismology has been demonstrated as a powerful tool for informing Galactic archaeology investigations. The launch of the NASA TESS mission has enabled seismic-based inferences to go full sky-providing a clear advantage for large ensemble studies of the different Milky Way components. Here we demonstrate its potential for investigating the Galaxy by carrying out the first asteroseismic ensemble study of red giant stars observed by TESS. We use a sample of 25 stars for which we measure their global asteroseimic observables and estimate their fundamental stellar properties, such as radius, mass, and age. Significant improvements are seen in the uncertainties of our estimates when combining seismic observables from TESS with astrometric measurements from the Gaia mission compared to when the seismology and astrometry are applied separately. Specifically, when combined we show that stellar radii can be determined to a precision of a few percent, masses to 5-10% and ages to the 20% level. This is comparable to the precision typically obtained using end-of-mission Kepler data.

Symposium - International Astronomical Union

Warning to the unsuspecting reader: The editors of this volume have (bravely) asked me to “preser... more Warning to the unsuspecting reader: The editors of this volume have (bravely) asked me to “preserve the spirit” of my oral presentation. It is difficult to translate the stirring grandeur of a multi-coloured flashing bowtie into mere words and diagrams. Failing to evoke that grandeur, I have instead settled for occasionally capturing the tackiness of my battery-operated talk in Kyoto.

Monthly Notices of the Royal Astronomical Society

The magnetic chemically peculiar (Ap/CP2) star 21 Com has been extensively studied in the past, a... more The magnetic chemically peculiar (Ap/CP2) star 21 Com has been extensively studied in the past, albeit with widely differing and sometimes contradictory results, in particular concerning the occurrence of short-term variability between about 5 to 90 min. We have performed a new investigation of 21 Com using Microvariability and Oscillations of Star (MOST) satellite and high-cadence ground-based photometry, time series spectroscopy, and evolutionary and pulsational modelling. Our analysis confirms that 21 Com is a classical CP2 star showing increased abundances of, in particular, Cr and Sr. From spectroscopic analysis, we have derived T eff = 8 900 ± 200 K, log g = 3.9 ± 0.2, and υsin i = 63 ± 2 km s −1. Our modelling efforts suggest that 21 Com is a main sequence (MS) star seen equator-on with a mass of 2.29 ± 0.10 M and a radius of R = 2.6 ± 0.2 R. Our extensive photometric data confirm the existence of rotational light variability with a period of 2.052 19(2) d. However, no significant frequencies with a semi-amplitude exceeding 0.2 mmag were found in the frequency range from 5 to 399 d −1. Our RV data also do not indicate short-term variability. We calculated pulsational models assuming different metallicities and ages, which do not predict the occurrence of unstable modes. The star 18 Com, often employed as comparison star for 21 Com in the past, has been identified as a periodic variable (P = 1.416 45 d). While it is impossible to assess whether 21 Com has exhibited short-term variability in the past, the new observational data and several issues/inconsistencies identified in previous studies strongly suggest that 21 Com is neither a δ Scuti nor a roAp pulsator but a 'well-behaved' CP2 star exhibiting its trademark rotational variability.

The Astrophysical Journal, 2007