We report the abundance analysis of one red giant branch star in the metal-poor outer halo globul... more We report the abundance analysis of one red giant branch star in the metal-poor outer halo globular cluster NGC 5694. We obtain [Fe/H] = -1.93, based on the ionized lines, and our metallicity measurement is in good agreement with previous estimates. We find that [Ca+Ti/2Fe] and [Cu/Fe] of NGC 5694 are about 0.3 -- 0.4 dex lower than other globular
The pulsating white dwarf G29-38 possesses a dust disk and metal lines attributed to the accretio... more The pulsating white dwarf G29-38 possesses a dust disk and metal lines attributed to the accretion of its disk material. \citet{vonhipg29} have reported variability in the equivalent width of G29-38's CaII K line on the timescale of days. We use high resolution optical spectroscopy of G29-38's CaII K line to test this observation. Over six days spanning in June 2007
We report the detection in Ks-band of the secondary eclipse of the hot Jupiter CoRoT-1b, from tim... more We report the detection in Ks-band of the secondary eclipse of the hot Jupiter CoRoT-1b, from time series photometry with the ARC 3.5-m telescope at Apache Point Observatory. The eclipse shows a depth of 0.336+/-0.042 percent and is centered at phase 0.5022 (+0.0023,-0.0027), consistent with a zero eccentricity orbit ecos{\omega} = 0.0035 (+0.0036,-0.0042). We perform the first optical to near-infrared
Proceedings of the International Astronomical Union
Eclipsing binary stars provide highly accurate measurements of the fundamental physical propertie... more Eclipsing binary stars provide highly accurate measurements of the fundamental physical properties of stars. They therefore serve as stringent tests of the predictions of evolutionary models upon which most stellar age determinations are based. Models generally perform very well in predicting coeval ages for eclipsing binaries with main-sequence components more massive than ~1.2 Msun; relative ages are good to ~5% or better in this mass regime. Low-mass main-sequence stars (M < 0.8 Msun) reveal large discrepancies in the model predicted ages, primarily due to magnetic activity in the observed stars that appears to inhibit convection and likely causes the radii to be 10-20% larger than predicted. In mass-radius diagrams these stars thus appear 50-90% older or younger than they really are. Aside from these activity-related effects, low-mass pre--main-sequence stars at ages ~1 Myr can also show non-coevality of ~30% due to star formation effects, however these effects are largely er...
Single metal polluted white dwarfs with no dusty disks are believed to be actively accreting meta... more Single metal polluted white dwarfs with no dusty disks are believed to be actively accreting metals from a circumstellar disk of gas caused by the destruction of asteroids perturbed by planetary systems. We report, for the first time, the detection of circumstellar Ca~II gas in absorption around the DAZ WD~1124-293, which lacks an infrared excess. We constrain the gas to $>$7 $R_{\rm WD}$ and $<$32000~AU, and estimate it to be at $\sim$54~R$_{\rm WD}$, well within WD~1124-293's tidal disruption radius. This detection is based on several epochs of spectroscopy around the Ca~II H and K lines ($\lambda$=3968\AA, 3933\AA) with the MIKE spectrograph on the Magellan/Clay Telescope at Las Campanas Observatory. We confirm the circumstellar nature of the gas by observing nearby sightlines and finding no evidence for gas from the local interstellar medium. Through archival data we have measured the equivalent width of the two photospheric Ca lines over a period of 11 years. We see $...
We report on the discovery of J0644+3344, a bright deeply eclipsing cataclysmic variable (CV) bin... more We report on the discovery of J0644+3344, a bright deeply eclipsing cataclysmic variable (CV) binary. Spectral signatures of both binary components and an accretion disk can be seen at optical wavelengths. The optical spectrum shows broad H I, He I, and He II accretion disk emission lines with deep narrow absorption components from H I, He I, Mg II and Ca II. The absorption lines are seen throughout the orbital period, disappearing only during primary eclipse. These absorption lines are either the the result of an optically-thick inner accretion disk or from the photosphere of the primary star. Radial velocity measurements show that the H I, He I, and Mg II absorption lines phase with the the primary star, while weak absorption features in the continuum phase with the secondary star. Radial velocity solutions give a 150+/-4 km/s semi-amplitude for the primary star and 192.8+/-5.6 km/s for the secondary. The individual stellar masses are 0.63-0.69 Mdot for the primary and 0.49-0.54 M...
The EChO core science will be based on a three tier survey, each with increasing sensitivity, in ... more The EChO core science will be based on a three tier survey, each with increasing sensitivity, in order to study the population of exo-planets from super-Earths to Jupiter-like planets, in the very hot to temperate zones (temperatures of 300 K - 3000 K) of F to M-type host stars. To achieve a meaningful outcome an accurate selection of the target sample is needed. In this paper we analyse the targets, suitable for EChO observations, expected to result from a sample of present and forthcoming detection surveys. Exoplanets currently known are already sufficient to provide a large and diverse sample. However we expect the results from these surveys to increase the sample of smaller planets that will allow us to optimize the EChO sample selection.
Very recently, we were able to measure CO absorption features in the atmosphere of the non-transi... more Very recently, we were able to measure CO absorption features in the atmosphere of the non-transiting planet τ Boo b for the very first time. This allowed us to unravel a long-term mystery in planet atmosphere studies, the determination of the orbital inclination of a non-transiting planet and the exact planetary mass, respectively being 46o and 5.7 M_Jup. In light of these new results, we reanalyzed a UVES/VLT data set taken by us with the goal to detect starlight reflected from this hot Jupiter. In the previous analysis of these data, we found a candidate signal of low confidence (2σ), indicating a geometric albedo of the planetary atmosphere lower than 0.4 and an orbital inclination of 41o, which is close to the recently measured value. We reanalyzed these data by adopting updated orbital parameters and find as result that the candidate signal of marginal significance now appears at an orbital inclination of 43o.
We present ground-based observations of the transiting Neptune-mass planet Gl 436b obtained with ... more We present ground-based observations of the transiting Neptune-mass planet Gl 436b obtained with the 3.5 m telescope at Apache Point Observatory and other supporting telescopes. Included in this is an observed transit in early 2005, over 2 years before the earliest reported transit detection. We have compiled all available transit data to date and perform a uniform modeling using the
We present preliminary results of the angular diameter measurements of low-mass, K- and M-type ma... more We present preliminary results of the angular diameter measurements of low-mass, K- and M-type main sequence stars from interferometric observations with the CHARA Array. The principal goal of this study consists of providing direct measurements of linear radii and effective temperatures for these stars. The sparse amount of data currently available on late-type stellar radii and temperatures indicates a continuing
We present measurements of fundamental astrophysical properties of nearby, low-mass, K- and M-dwa... more We present measurements of fundamental astrophysical properties of nearby, low-mass, K- and M-dwarfs from our DISCOS survey (DIameterS of COol Stars). The principal goal of our study is the determination of linear radii and effective temperatures for these stars. We calculate their radii from angular diameter measurements using the CHARA Array and Hipparcos distances. Combined with bolometric flux measurements based
Exoplanet phase curves provide a wealth of information about atmospheric dynamics, energetics, an... more Exoplanet phase curves provide a wealth of information about atmospheric dynamics, energetics, and chemistry. Phase curves have been observed for relatively few planets, yet the current small sample already hints at the inadequacy of current atmospheric models. Our ultimate goal of understanding the global circulation patterns and their relation to atmospheric chemistry requires a larger and more homogenous sample. Here, we propose to more than double the sample of hot Jupiters with high S/N phase observations by targeting five bright non-transiting systems. Combined with the powerful new technique of high-resolution infrared Doppler spectroscopy, our observations will enable an unprecedented comparative study to relate global circulation patterns and atmospheric chemistry, and ultimately facilitate retrieval of the first global abundance and temperature maps of extrasolar planets. The planets in our sample represent the best objects to leverage both space-based phase curves and gro...
Publications of The Astronomical Society of The Pacific, 2007
We report precipitable water vapor (PWV) measurements made at Las Campanas Observatory using opti... more We report precipitable water vapor (PWV) measurements made at Las Campanas Observatory using optical spectra of H2O lines obtained with the Magellan echelle spectrograph, and calculated using a robust technique that is accurate to 5%-10%. Calibration of the relationship between our PWV measurements and opacity values at 225 GHz was made possible by simultaneous observations with a tipping radiometer. Based
This work focuses on determining the fundamental properties of nearby, main sequence, A, F, G, K,... more This work focuses on determining the fundamental properties of nearby, main sequence, A, F, G, K, and M-type stars. We present the results of angular diameters (average error 1.5%) obtained via interferometric observations made with the CHARA Array. These measurements combined with HIPPARCOS and ground-based parallaxes and bolometric fluxes provide an empirical determination of their effective temperatures, linear radii, and
We report the discovery of a new detached eclipsing binary known as NSVS01031772 with component m... more We report the discovery of a new detached eclipsing binary known as NSVS01031772 with component masses M_1= 0.5428 +/- 0.0027Msun, M_2= 0.4982 +/- 0.0025Msun, and radii R_1= 0.5260 +/- 0.0028Rsun, R_2= 0.5088 +/- 0.0030Rsun. The system has an orbital period of 0.3681414(3) days and an apparent magnitude V ~ 12.6. The estimated effective temperatures of the stars are T_eff1 =
I will present results on an ongoing large ESO program on the 10.4 meter Gran Telescopio Canarias... more I will present results on an ongoing large ESO program on the 10.4 meter Gran Telescopio Canarias (GTC) telescope performing an optical survey of transiting exoplanet atmospheres, including 10 hot-Jupiters and a super-Earth. Our observations use a unique tunable filter, capable of photon-limited sub-mmag narrowband transit spectrophotometry, capable of detecting Na, K, TiO and other important atmospheric species. With a large aperture coupled with fast photometry, our observations can perform transmission spectrophotometry for a wide range of hot-Jupiter atmospheres, including fainter targets, allowing for comparative exoplanetary atmospheric studies. The first observations from this program detected potassium in XO-2b, the first time this important alkali metal was found on an exoplanet. I will detail the further results of our survey including the hot-Jupiters Hat-P-1b, Tres-2b, Hat-P-6b, and XO-2b, as well as the super-Earth GJ1214b, and compare the different atmospheres we are d...
We report the abundance analysis of one red giant branch star in the metal-poor outer halo globul... more We report the abundance analysis of one red giant branch star in the metal-poor outer halo globular cluster NGC 5694. We obtain [Fe/H] = -1.93, based on the ionized lines, and our metallicity measurement is in good agreement with previous estimates. We find that [Ca+Ti/2Fe] and [Cu/Fe] of NGC 5694 are about 0.3 -- 0.4 dex lower than other globular
The pulsating white dwarf G29-38 possesses a dust disk and metal lines attributed to the accretio... more The pulsating white dwarf G29-38 possesses a dust disk and metal lines attributed to the accretion of its disk material. \citet{vonhipg29} have reported variability in the equivalent width of G29-38's CaII K line on the timescale of days. We use high resolution optical spectroscopy of G29-38's CaII K line to test this observation. Over six days spanning in June 2007
We report the detection in Ks-band of the secondary eclipse of the hot Jupiter CoRoT-1b, from tim... more We report the detection in Ks-band of the secondary eclipse of the hot Jupiter CoRoT-1b, from time series photometry with the ARC 3.5-m telescope at Apache Point Observatory. The eclipse shows a depth of 0.336+/-0.042 percent and is centered at phase 0.5022 (+0.0023,-0.0027), consistent with a zero eccentricity orbit ecos{\omega} = 0.0035 (+0.0036,-0.0042). We perform the first optical to near-infrared
Proceedings of the International Astronomical Union
Eclipsing binary stars provide highly accurate measurements of the fundamental physical propertie... more Eclipsing binary stars provide highly accurate measurements of the fundamental physical properties of stars. They therefore serve as stringent tests of the predictions of evolutionary models upon which most stellar age determinations are based. Models generally perform very well in predicting coeval ages for eclipsing binaries with main-sequence components more massive than ~1.2 Msun; relative ages are good to ~5% or better in this mass regime. Low-mass main-sequence stars (M < 0.8 Msun) reveal large discrepancies in the model predicted ages, primarily due to magnetic activity in the observed stars that appears to inhibit convection and likely causes the radii to be 10-20% larger than predicted. In mass-radius diagrams these stars thus appear 50-90% older or younger than they really are. Aside from these activity-related effects, low-mass pre--main-sequence stars at ages ~1 Myr can also show non-coevality of ~30% due to star formation effects, however these effects are largely er...
Single metal polluted white dwarfs with no dusty disks are believed to be actively accreting meta... more Single metal polluted white dwarfs with no dusty disks are believed to be actively accreting metals from a circumstellar disk of gas caused by the destruction of asteroids perturbed by planetary systems. We report, for the first time, the detection of circumstellar Ca~II gas in absorption around the DAZ WD~1124-293, which lacks an infrared excess. We constrain the gas to $>$7 $R_{\rm WD}$ and $<$32000~AU, and estimate it to be at $\sim$54~R$_{\rm WD}$, well within WD~1124-293's tidal disruption radius. This detection is based on several epochs of spectroscopy around the Ca~II H and K lines ($\lambda$=3968\AA, 3933\AA) with the MIKE spectrograph on the Magellan/Clay Telescope at Las Campanas Observatory. We confirm the circumstellar nature of the gas by observing nearby sightlines and finding no evidence for gas from the local interstellar medium. Through archival data we have measured the equivalent width of the two photospheric Ca lines over a period of 11 years. We see $...
We report on the discovery of J0644+3344, a bright deeply eclipsing cataclysmic variable (CV) bin... more We report on the discovery of J0644+3344, a bright deeply eclipsing cataclysmic variable (CV) binary. Spectral signatures of both binary components and an accretion disk can be seen at optical wavelengths. The optical spectrum shows broad H I, He I, and He II accretion disk emission lines with deep narrow absorption components from H I, He I, Mg II and Ca II. The absorption lines are seen throughout the orbital period, disappearing only during primary eclipse. These absorption lines are either the the result of an optically-thick inner accretion disk or from the photosphere of the primary star. Radial velocity measurements show that the H I, He I, and Mg II absorption lines phase with the the primary star, while weak absorption features in the continuum phase with the secondary star. Radial velocity solutions give a 150+/-4 km/s semi-amplitude for the primary star and 192.8+/-5.6 km/s for the secondary. The individual stellar masses are 0.63-0.69 Mdot for the primary and 0.49-0.54 M...
The EChO core science will be based on a three tier survey, each with increasing sensitivity, in ... more The EChO core science will be based on a three tier survey, each with increasing sensitivity, in order to study the population of exo-planets from super-Earths to Jupiter-like planets, in the very hot to temperate zones (temperatures of 300 K - 3000 K) of F to M-type host stars. To achieve a meaningful outcome an accurate selection of the target sample is needed. In this paper we analyse the targets, suitable for EChO observations, expected to result from a sample of present and forthcoming detection surveys. Exoplanets currently known are already sufficient to provide a large and diverse sample. However we expect the results from these surveys to increase the sample of smaller planets that will allow us to optimize the EChO sample selection.
Very recently, we were able to measure CO absorption features in the atmosphere of the non-transi... more Very recently, we were able to measure CO absorption features in the atmosphere of the non-transiting planet τ Boo b for the very first time. This allowed us to unravel a long-term mystery in planet atmosphere studies, the determination of the orbital inclination of a non-transiting planet and the exact planetary mass, respectively being 46o and 5.7 M_Jup. In light of these new results, we reanalyzed a UVES/VLT data set taken by us with the goal to detect starlight reflected from this hot Jupiter. In the previous analysis of these data, we found a candidate signal of low confidence (2σ), indicating a geometric albedo of the planetary atmosphere lower than 0.4 and an orbital inclination of 41o, which is close to the recently measured value. We reanalyzed these data by adopting updated orbital parameters and find as result that the candidate signal of marginal significance now appears at an orbital inclination of 43o.
We present ground-based observations of the transiting Neptune-mass planet Gl 436b obtained with ... more We present ground-based observations of the transiting Neptune-mass planet Gl 436b obtained with the 3.5 m telescope at Apache Point Observatory and other supporting telescopes. Included in this is an observed transit in early 2005, over 2 years before the earliest reported transit detection. We have compiled all available transit data to date and perform a uniform modeling using the
We present preliminary results of the angular diameter measurements of low-mass, K- and M-type ma... more We present preliminary results of the angular diameter measurements of low-mass, K- and M-type main sequence stars from interferometric observations with the CHARA Array. The principal goal of this study consists of providing direct measurements of linear radii and effective temperatures for these stars. The sparse amount of data currently available on late-type stellar radii and temperatures indicates a continuing
We present measurements of fundamental astrophysical properties of nearby, low-mass, K- and M-dwa... more We present measurements of fundamental astrophysical properties of nearby, low-mass, K- and M-dwarfs from our DISCOS survey (DIameterS of COol Stars). The principal goal of our study is the determination of linear radii and effective temperatures for these stars. We calculate their radii from angular diameter measurements using the CHARA Array and Hipparcos distances. Combined with bolometric flux measurements based
Exoplanet phase curves provide a wealth of information about atmospheric dynamics, energetics, an... more Exoplanet phase curves provide a wealth of information about atmospheric dynamics, energetics, and chemistry. Phase curves have been observed for relatively few planets, yet the current small sample already hints at the inadequacy of current atmospheric models. Our ultimate goal of understanding the global circulation patterns and their relation to atmospheric chemistry requires a larger and more homogenous sample. Here, we propose to more than double the sample of hot Jupiters with high S/N phase observations by targeting five bright non-transiting systems. Combined with the powerful new technique of high-resolution infrared Doppler spectroscopy, our observations will enable an unprecedented comparative study to relate global circulation patterns and atmospheric chemistry, and ultimately facilitate retrieval of the first global abundance and temperature maps of extrasolar planets. The planets in our sample represent the best objects to leverage both space-based phase curves and gro...
Publications of The Astronomical Society of The Pacific, 2007
We report precipitable water vapor (PWV) measurements made at Las Campanas Observatory using opti... more We report precipitable water vapor (PWV) measurements made at Las Campanas Observatory using optical spectra of H2O lines obtained with the Magellan echelle spectrograph, and calculated using a robust technique that is accurate to 5%-10%. Calibration of the relationship between our PWV measurements and opacity values at 225 GHz was made possible by simultaneous observations with a tipping radiometer. Based
This work focuses on determining the fundamental properties of nearby, main sequence, A, F, G, K,... more This work focuses on determining the fundamental properties of nearby, main sequence, A, F, G, K, and M-type stars. We present the results of angular diameters (average error 1.5%) obtained via interferometric observations made with the CHARA Array. These measurements combined with HIPPARCOS and ground-based parallaxes and bolometric fluxes provide an empirical determination of their effective temperatures, linear radii, and
We report the discovery of a new detached eclipsing binary known as NSVS01031772 with component m... more We report the discovery of a new detached eclipsing binary known as NSVS01031772 with component masses M_1= 0.5428 +/- 0.0027Msun, M_2= 0.4982 +/- 0.0025Msun, and radii R_1= 0.5260 +/- 0.0028Rsun, R_2= 0.5088 +/- 0.0030Rsun. The system has an orbital period of 0.3681414(3) days and an apparent magnitude V ~ 12.6. The estimated effective temperatures of the stars are T_eff1 =
I will present results on an ongoing large ESO program on the 10.4 meter Gran Telescopio Canarias... more I will present results on an ongoing large ESO program on the 10.4 meter Gran Telescopio Canarias (GTC) telescope performing an optical survey of transiting exoplanet atmospheres, including 10 hot-Jupiters and a super-Earth. Our observations use a unique tunable filter, capable of photon-limited sub-mmag narrowband transit spectrophotometry, capable of detecting Na, K, TiO and other important atmospheric species. With a large aperture coupled with fast photometry, our observations can perform transmission spectrophotometry for a wide range of hot-Jupiter atmospheres, including fainter targets, allowing for comparative exoplanetary atmospheric studies. The first observations from this program detected potassium in XO-2b, the first time this important alkali metal was found on an exoplanet. I will detail the further results of our survey including the hot-Jupiters Hat-P-1b, Tres-2b, Hat-P-6b, and XO-2b, as well as the super-Earth GJ1214b, and compare the different atmospheres we are d...
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Papers by Mercedes Lopez-morales