Marcelo Emilio - Academia.edu (original) (raw)

Papers by Marcelo Emilio

Japan Geoscience Union, 2018

We report the current status of the T40 and T60 telescope activities including the onboard instru... more We report the current status of the T40 and T60 telescope activities including the onboard instruments as well as the updates of 1.8-m aperture telescope PLANETS project at Haleakala dedicated to planetary and exoplanetary observations. Continuous monitoring is essential to understand the planetary atmospheric phenomena, and therefore, own facilities with even smalland medium sized telescopes and instruments are important. The location of our telescopes, the Haleakala High Altitude Observatories at the summit of Mt. Haleakala is sufficiently high (3050m), and one of the best sites with clear sky, good seeing, and low humidity conditions. On the summit, our group is now operating a 40 cm Schmidt-Cassegrain (T40) and 60 cm Cassegrain (T60) telescopes. T40 telescope is mainly observing faint atmospheric features such as Io torus, Mercury, and so on. It has uniquely provided long-term Io torus activities for more than ten years. T60 is now observing planetary atmospheres in visible and ...

We report the current status of small-telescope activities and the 1.8-m aperture telescope PLANE... more We report the current status of small-telescope activities and the 1.8-m aperture telescope PLANETS project at Haleakala dedicated to planetary and exoplanetary observations. Continuous monitoring is essential to understand the planetary atmospheric phenomena, and therefore, own facilities with even small- and medium sized telescopes and instruments are important. On the summit of Mt. Haleakala, Hawaii, we are operating a 40 cm (T40) and 60 cm (T60) telescopes for measuring faint atmospheric features such as Io torus, Mercury, and so on. It has uniquely provided long-term Io torus activities for more than ten years. T60 is now observing planetary atmospheres in visible and infrared ranges. The polarization imager DIPOL-2 is also installed to measure the weak polarization of exoplanetary light. In addition, we are carrying out a 1.8-m off-axis telescope project PLANETS at Haleakala. This project is managed by the PLANETS Foundation (www.planets.life) is an international collaboration...

PLANETS will be a 1.8-m off-axis telescope combined with contrast enhancement techniques, enablin... more PLANETS will be a 1.8-m off-axis telescope combined with contrast enhancement techniques, enabling us to observe faint emissions in the vicinity of bright objects. This “high dynamic-range” capability is largely dependent upon precision of telescope optics as well as atmospheric distortion. We present feasibility study of monitoring water plumes on Europa, neutral torus close to Enceladus, and ionosphere on Mars using PLANETS telescope. To test feasibility of high dynamic-range observation under actual conditions of wavefront error, we modeled propagation of light though the system based on Fraunhofer calculation taking into account for wavefront error made by atmospheric distortion and by primary mirror figure error. Then point spread function is calculated for several cases of figure errors under use of adaptive optics. The modeling result predicts that the moderate or high-precision primary mirror is mandatory to accomplish the high dynamic-range observation. We also present the ...

We present the first results of the analysis of the light curve of the B5IVe star HD 181231 obtai... more We present the first results of the analysis of the light curve of the B5IVe star HD 181231 obtained during a long run (5 months) of the CoRoT mission. The light curve shows clear pulsations and even beating effects. Several frequencies are detected. Ground-based spec- troscopic data have also been analyzed and help to determine the rotation frequency and identify pulsation modes.

In this work we describe the method and results of precise solar astrometry made with the Michels... more In this work we describe the method and results of precise solar astrometry made with the Michelson Doppler Imager (MDI), on board the Solar and Heliospheric Observatory (SOHO), during one complete solar cycle. We measured an upper limit to the solar radius variation, the absolute solar radius value and the solar shape. Our results are 22 mas peakto-peak upper limit for the solar radius variation over the solar cycle, the absolute radius was measured as 959.28 ± 0.15 arcsec at 1 AU and the difference between polar and equatorial solar radii in 1997 was 5 km and about three times larger in 2001.

Proceedings of the International Astronomical Union

Planetary transits are used to measure the solar radius since the beginning of the 18th century a... more Planetary transits are used to measure the solar radius since the beginning of the 18th century and are the most accurate direct method to measure potentially long-term variation in the solar size. Historical measures present a range of values dominated by systematic errors from different instruments and observers. Atmospheric seeing and black drop effect contribute as error sources for the precise timing of the planetary transit ground observations. Both Solar and Heliospheric Observatory (SOHO) and Solar Dynamics Observatory (SDO) made observations of planetary transits from space to derive the solar radius. The International Astronomical Union approved the resolution B3 in 2015, defining a nominal solar radius of precisely 695,700 km. In this work, we show that this value is off by more than 300 km, which is one order of magnitude higher than the error of the most recent solar radius observations.

Proceedings of the International Astronomical Union

If biologically complex molecules as DNA were present in the extraterrestrial targets, their spec... more If biologically complex molecules as DNA were present in the extraterrestrial targets, their spectral signatures would be rather difficult to be unambiguously identified. As a matter of fact, the molecular array of a single nucleobasis will generate a tangled spectral signature. On the other hand, a part of it, e.g. bands due to the group of HNCO of guanine may have been detected but associated to smaller molecules, e.g. isocianic acid (HNCO). However, if comprised in a nucleobasis, its detection would be misinterpreted. Five key transitions were preliminarly selected for either purines and pyrimidines that should be observed together in the same target. If this happens, it may be that we are detecting the whole from its parts.

Monthly Notices of the Royal Astronomical Society

We report in this paper spectroscopic and photometric analysis of eight massive stars observed du... more We report in this paper spectroscopic and photometric analysis of eight massive stars observed during the Campaign 8 of the Kepler/K2 mission from January to March 2016. Spectroscopic data were obtained on these stars at OPD/LNA, Brazil. The stellar parameters were determined using SME, and periodic analyses of the light curves were performed through CLEANEST and PERIOD04 algorithms. Mass, luminosity, and radius of our stars were estimated employing CESAM+POSC grids. Three of our stars show significant periodicity. K2 ID 220679442 and K2 ID 220532854 have periods linked to the stellar rotation. K2 ID 220532854 has prominent silicon lines (Si II λ4128–4131), a characteristic presented in the peculiar class of Ap magnetic main sequence stars. However, in our spectral analysis, this object was found to be an evolved, luminous giant star. K2 ID 220466722 was revealed to be a δ Scuti variable, and 40 individual frequencies were determined for this star. No significant periodicity was fou...

Symposium - International Astronomical Union

A regular program of observations of the Sun with prismatic astrolabes is under way since 1974 in... more A regular program of observations of the Sun with prismatic astrolabes is under way since 1974 in both, the “Abrahão de Moraes” (φ = −23°0.1′) and “Caussols” (φ = +43°44.9′) observatories. The zenith distance of 2968 transits of the solar limbs observed during the period from 1988 January to 1994 April, in both centers, are analysed. The primary goal of this programme is to determine corrections ΔE and ΔA to the FK5 equinox and equator, as well as to the…

Physical Review Letters

The Sun's internal rotation Ω , Θ has previously been measured using helioseismology techniques a... more The Sun's internal rotation Ω , Θ has previously been measured using helioseismology techniques and found to be a complex function of co-latitude, θ, and radius, r. From helioseismology and observations of apparently "rooted" solar magnetic tracers we know that the surface rotates more slowly than much of the interior. The cause of this slowdown is not understood but it is important for understanding stellar rotation generally and any plausible theory of the solar interior. A new analysis using 5-min solar p-mode limb oscillations as a rotation "tracer" finds an even larger velocity gradient in a thin region at the top of the photosphere. This shear occurs where the solar atmosphere radiates energy and angular momentum. We suggest that the net effect of the photospheric angular momentum loss is similar to Poynting-Robertson "photon braking" on, for example, Sun-orbiting dust. The resultant photospheric torque is readily computed and, over the Sun's lifetime, is found to be comparable to the apparent angular momentum deficit in the near-surface shear layer. I.

Monthly Notices of the Royal Astronomical Society

We present MCDA, a modification of the CoRoT detrend algorithm (CDA) suitable to detrend chromati... more We present MCDA, a modification of the CoRoT detrend algorithm (CDA) suitable to detrend chromatic light curves. By means of robust statistics and better handling of short term variability, the implementation decreases the systematic light curve variations and improves the detection of exoplanets when compared with the original algorithm. All CoRoT chromatic light curves (a total of 65,655) were analysed with our algorithm. Dozens of new transit candidates and all previously known CoRoT exoplanets were rediscovered in those light curves using a box-fitting algorithm. For three of the new cases spectroscopic measurements of the candidates' host stars were retrieved from the ESO Science Archive Facility and used to calculate stellar parameters and, in the best cases, radial velocities. In addition to our improved detrend technique we announce the discovery of a planet that orbits a 0.79 +0.08 −0.09 R ⊙ star with a period of 6.71837 ± 0.00001 days and has 0.57 +0.06 −0.05 R J and 0.15 ± 0.10 M J. We also present the analysis of two cases in which parameters found suggest the existence of possible planetary companions.

Proceedings of The International Astronomical Union, 1996

In this work we describe the method and results of precise solar astrometry made with the Michels... more In this work we describe the method and results of precise solar astrometry made with the Michelson Doppler Imager (MDI), on board the Solar and Heliospheric Observatory (SOHO), during one complete solar cycle. We measured an upper limit to the solar radius variation, the absolute solar radius value and the solar shape. Our results are 22 mas peakto-peak upper limit for the solar radius variation over the solar cycle, the absolute radius was measured as 959.28 ± 0.15 arcsec at 1 AU and the difference between polar and equatorial solar radii in 1997 was 5 km and about three times larger in 2001.

Proceedings of the International Astronomical Union, 2012

Non gaussian sources of erros need to be taken into consideration when searching for planetary tr... more Non gaussian sources of erros need to be taken into consideration when searching for planetary transits. Such phenomena are mostly caused by the impact of high energetic particles on the detector (Pinheiro da Silva et al. 2008). The detection efficiency of transits, therefor, depend significantly on the data quality and the algorithms utilized to deal with these errors sources. In this work we show that a modified detrend algorithm CDA (CoRoT Detrend Algorithm; Mislis et al. 2010) using a robust statistics and an empirical fit, instead of a polynomial one, can eliminate more efficiently gaps in the data and other long-term trends from the light-curve. Using this algorithm enables us to obtain a reconstructed light-curve with better signal-to-noise ratio that allows to improve the detection of exoplanet transits, although long term signals are destroyed. The results show that these modifications lead to an improved BLS (Box-fitting Least Squares; Kovács, Zucker & Mazeh 2002) algorith...

Japan Geoscience Union, 2018

We report the current status of the T40 and T60 telescope activities including the onboard instru... more We report the current status of the T40 and T60 telescope activities including the onboard instruments as well as the updates of 1.8-m aperture telescope PLANETS project at Haleakala dedicated to planetary and exoplanetary observations. Continuous monitoring is essential to understand the planetary atmospheric phenomena, and therefore, own facilities with even smalland medium sized telescopes and instruments are important. The location of our telescopes, the Haleakala High Altitude Observatories at the summit of Mt. Haleakala is sufficiently high (3050m), and one of the best sites with clear sky, good seeing, and low humidity conditions. On the summit, our group is now operating a 40 cm Schmidt-Cassegrain (T40) and 60 cm Cassegrain (T60) telescopes. T40 telescope is mainly observing faint atmospheric features such as Io torus, Mercury, and so on. It has uniquely provided long-term Io torus activities for more than ten years. T60 is now observing planetary atmospheres in visible and ...

We report the current status of small-telescope activities and the 1.8-m aperture telescope PLANE... more We report the current status of small-telescope activities and the 1.8-m aperture telescope PLANETS project at Haleakala dedicated to planetary and exoplanetary observations. Continuous monitoring is essential to understand the planetary atmospheric phenomena, and therefore, own facilities with even small- and medium sized telescopes and instruments are important. On the summit of Mt. Haleakala, Hawaii, we are operating a 40 cm (T40) and 60 cm (T60) telescopes for measuring faint atmospheric features such as Io torus, Mercury, and so on. It has uniquely provided long-term Io torus activities for more than ten years. T60 is now observing planetary atmospheres in visible and infrared ranges. The polarization imager DIPOL-2 is also installed to measure the weak polarization of exoplanetary light. In addition, we are carrying out a 1.8-m off-axis telescope project PLANETS at Haleakala. This project is managed by the PLANETS Foundation (www.planets.life) is an international collaboration...

PLANETS will be a 1.8-m off-axis telescope combined with contrast enhancement techniques, enablin... more PLANETS will be a 1.8-m off-axis telescope combined with contrast enhancement techniques, enabling us to observe faint emissions in the vicinity of bright objects. This “high dynamic-range” capability is largely dependent upon precision of telescope optics as well as atmospheric distortion. We present feasibility study of monitoring water plumes on Europa, neutral torus close to Enceladus, and ionosphere on Mars using PLANETS telescope. To test feasibility of high dynamic-range observation under actual conditions of wavefront error, we modeled propagation of light though the system based on Fraunhofer calculation taking into account for wavefront error made by atmospheric distortion and by primary mirror figure error. Then point spread function is calculated for several cases of figure errors under use of adaptive optics. The modeling result predicts that the moderate or high-precision primary mirror is mandatory to accomplish the high dynamic-range observation. We also present the ...

We present the first results of the analysis of the light curve of the B5IVe star HD 181231 obtai... more We present the first results of the analysis of the light curve of the B5IVe star HD 181231 obtained during a long run (5 months) of the CoRoT mission. The light curve shows clear pulsations and even beating effects. Several frequencies are detected. Ground-based spec- troscopic data have also been analyzed and help to determine the rotation frequency and identify pulsation modes.

In this work we describe the method and results of precise solar astrometry made with the Michels... more In this work we describe the method and results of precise solar astrometry made with the Michelson Doppler Imager (MDI), on board the Solar and Heliospheric Observatory (SOHO), during one complete solar cycle. We measured an upper limit to the solar radius variation, the absolute solar radius value and the solar shape. Our results are 22 mas peakto-peak upper limit for the solar radius variation over the solar cycle, the absolute radius was measured as 959.28 ± 0.15 arcsec at 1 AU and the difference between polar and equatorial solar radii in 1997 was 5 km and about three times larger in 2001.

Proceedings of the International Astronomical Union

Planetary transits are used to measure the solar radius since the beginning of the 18th century a... more Planetary transits are used to measure the solar radius since the beginning of the 18th century and are the most accurate direct method to measure potentially long-term variation in the solar size. Historical measures present a range of values dominated by systematic errors from different instruments and observers. Atmospheric seeing and black drop effect contribute as error sources for the precise timing of the planetary transit ground observations. Both Solar and Heliospheric Observatory (SOHO) and Solar Dynamics Observatory (SDO) made observations of planetary transits from space to derive the solar radius. The International Astronomical Union approved the resolution B3 in 2015, defining a nominal solar radius of precisely 695,700 km. In this work, we show that this value is off by more than 300 km, which is one order of magnitude higher than the error of the most recent solar radius observations.

Proceedings of the International Astronomical Union

If biologically complex molecules as DNA were present in the extraterrestrial targets, their spec... more If biologically complex molecules as DNA were present in the extraterrestrial targets, their spectral signatures would be rather difficult to be unambiguously identified. As a matter of fact, the molecular array of a single nucleobasis will generate a tangled spectral signature. On the other hand, a part of it, e.g. bands due to the group of HNCO of guanine may have been detected but associated to smaller molecules, e.g. isocianic acid (HNCO). However, if comprised in a nucleobasis, its detection would be misinterpreted. Five key transitions were preliminarly selected for either purines and pyrimidines that should be observed together in the same target. If this happens, it may be that we are detecting the whole from its parts.

Monthly Notices of the Royal Astronomical Society

We report in this paper spectroscopic and photometric analysis of eight massive stars observed du... more We report in this paper spectroscopic and photometric analysis of eight massive stars observed during the Campaign 8 of the Kepler/K2 mission from January to March 2016. Spectroscopic data were obtained on these stars at OPD/LNA, Brazil. The stellar parameters were determined using SME, and periodic analyses of the light curves were performed through CLEANEST and PERIOD04 algorithms. Mass, luminosity, and radius of our stars were estimated employing CESAM+POSC grids. Three of our stars show significant periodicity. K2 ID 220679442 and K2 ID 220532854 have periods linked to the stellar rotation. K2 ID 220532854 has prominent silicon lines (Si II λ4128–4131), a characteristic presented in the peculiar class of Ap magnetic main sequence stars. However, in our spectral analysis, this object was found to be an evolved, luminous giant star. K2 ID 220466722 was revealed to be a δ Scuti variable, and 40 individual frequencies were determined for this star. No significant periodicity was fou...

Symposium - International Astronomical Union

A regular program of observations of the Sun with prismatic astrolabes is under way since 1974 in... more A regular program of observations of the Sun with prismatic astrolabes is under way since 1974 in both, the “Abrahão de Moraes” (φ = −23°0.1′) and “Caussols” (φ = +43°44.9′) observatories. The zenith distance of 2968 transits of the solar limbs observed during the period from 1988 January to 1994 April, in both centers, are analysed. The primary goal of this programme is to determine corrections ΔE and ΔA to the FK5 equinox and equator, as well as to the…

Physical Review Letters

The Sun's internal rotation Ω , Θ has previously been measured using helioseismology techniques a... more The Sun's internal rotation Ω , Θ has previously been measured using helioseismology techniques and found to be a complex function of co-latitude, θ, and radius, r. From helioseismology and observations of apparently "rooted" solar magnetic tracers we know that the surface rotates more slowly than much of the interior. The cause of this slowdown is not understood but it is important for understanding stellar rotation generally and any plausible theory of the solar interior. A new analysis using 5-min solar p-mode limb oscillations as a rotation "tracer" finds an even larger velocity gradient in a thin region at the top of the photosphere. This shear occurs where the solar atmosphere radiates energy and angular momentum. We suggest that the net effect of the photospheric angular momentum loss is similar to Poynting-Robertson "photon braking" on, for example, Sun-orbiting dust. The resultant photospheric torque is readily computed and, over the Sun's lifetime, is found to be comparable to the apparent angular momentum deficit in the near-surface shear layer. I.

Monthly Notices of the Royal Astronomical Society

We present MCDA, a modification of the CoRoT detrend algorithm (CDA) suitable to detrend chromati... more We present MCDA, a modification of the CoRoT detrend algorithm (CDA) suitable to detrend chromatic light curves. By means of robust statistics and better handling of short term variability, the implementation decreases the systematic light curve variations and improves the detection of exoplanets when compared with the original algorithm. All CoRoT chromatic light curves (a total of 65,655) were analysed with our algorithm. Dozens of new transit candidates and all previously known CoRoT exoplanets were rediscovered in those light curves using a box-fitting algorithm. For three of the new cases spectroscopic measurements of the candidates' host stars were retrieved from the ESO Science Archive Facility and used to calculate stellar parameters and, in the best cases, radial velocities. In addition to our improved detrend technique we announce the discovery of a planet that orbits a 0.79 +0.08 −0.09 R ⊙ star with a period of 6.71837 ± 0.00001 days and has 0.57 +0.06 −0.05 R J and 0.15 ± 0.10 M J. We also present the analysis of two cases in which parameters found suggest the existence of possible planetary companions.

Proceedings of The International Astronomical Union, 1996

In this work we describe the method and results of precise solar astrometry made with the Michels... more In this work we describe the method and results of precise solar astrometry made with the Michelson Doppler Imager (MDI), on board the Solar and Heliospheric Observatory (SOHO), during one complete solar cycle. We measured an upper limit to the solar radius variation, the absolute solar radius value and the solar shape. Our results are 22 mas peakto-peak upper limit for the solar radius variation over the solar cycle, the absolute radius was measured as 959.28 ± 0.15 arcsec at 1 AU and the difference between polar and equatorial solar radii in 1997 was 5 km and about three times larger in 2001.

Proceedings of the International Astronomical Union, 2012

Non gaussian sources of erros need to be taken into consideration when searching for planetary tr... more Non gaussian sources of erros need to be taken into consideration when searching for planetary transits. Such phenomena are mostly caused by the impact of high energetic particles on the detector (Pinheiro da Silva et al. 2008). The detection efficiency of transits, therefor, depend significantly on the data quality and the algorithms utilized to deal with these errors sources. In this work we show that a modified detrend algorithm CDA (CoRoT Detrend Algorithm; Mislis et al. 2010) using a robust statistics and an empirical fit, instead of a polynomial one, can eliminate more efficiently gaps in the data and other long-term trends from the light-curve. Using this algorithm enables us to obtain a reconstructed light-curve with better signal-to-noise ratio that allows to improve the detection of exoplanet transits, although long term signals are destroyed. The results show that these modifications lead to an improved BLS (Box-fitting Least Squares; Kovács, Zucker & Mazeh 2002) algorith...