4 research outputs found
Red supergiants as cosmic abundance probes: The first direct metallicity determination of NGC 4038 in the antennae.
We present a direct determination of the stellar metallicity in the close pair galaxy NGC 4038 (D= 20 Mpc) based on the quantitative analysis of moderate resolution KMOS/VLT spectra of three super star clusters (SSCs). The method adopted in our analysis has been developed and optimised to measure accurate metallicities from atomic lines in the J-band of single red supergiant (RSG) or RSG-dominated star clusters. Hence, our metallicity measurements are not a_ected by the biases and poorly understood systematics inherent to strong line H II methods which are routinely applied to massive data sets of galaxies. We _nd [Z]= +0.07 _ 0.03 and compare our measurements to H II strong line calibrations. Our abundances and literature data suggest the presence of a at metallicity gradient, which can be explained as redistribution of metal-rich gas following the strong interaction
Exoplanet Research with the Stratospheric Observatory for Infrared Astronomy (SOFIA)
When the Stratospheric Observatory for Infrared Astronomy (SOFIA) was
conceived and its first science cases defined, exoplanets had not been
detected. Later studies, however, showed that optical and near-infrared
photometric and spectrophotometric follow-up observations during planetary
transits and eclipses are feasible with SOFIA's instrumentation, in particular
with the HIPO-FLITECAM and FPI+ optical and near infrared (NIR) instruments.
Additionally, the airborne-based platform SOFIA has a number of unique
advantages when compared to other ground- and space-based observatories in this
field of research. Here we will outline these theoretical advantages, present
some sample science cases and the results of two observations from SOFIA's
first five observation cycles -- an observation of the Hot Jupiter HD 189733b
with HIPO and an observation of the Super-Earth GJ 1214b with FLIPO and FPI+.
Based on these early products available to this science case, we evaluate
SOFIA's potential and future perspectives in the field of optical and infrared
exoplanet spectrophotometry in the stratosphere.Comment: Invited review chapter, accepted for publication in "Handbook of
Exoplanets" edited by H.J. Deeg and J.A. Belmonte, Springer Reference Work
Planet Hunters VII. Discovery of a New Low-Mass, Low-Density Planet (PH3 c) Orbiting Kepler-289 with Mass Measurements of Two Additional Planets (PH3 b and d)
We report the discovery of one newly confirmed planet ( days,
) and mass determinations of two previously
validated Kepler planets, Kepler-289 b ( days,
) and Kepler-289-c ( days,
), through their transit timing variations
(TTVs). We also exclude the possibility that these three planets reside in a
Laplace resonance. The outer planet has very deep (), high
signal-to-noise transits, which puts extremely tight constraints on its host
star's stellar properties via Kepler's Third Law. The star PH3 is a young
( Gyr as determined by isochrones and gyrochronology), Sun-like star
with , , and
K. The middle planet's large TTV amplitude (
hours) resulted either in non-detections or inaccurate detections in previous
searches. A strong chopping signal, a shorter period sinusoid in the TTVs,
allows us to break the mass-eccentricity degeneracy and uniquely determine the
masses of the inner, middle, and outer planets to be ,
, and , which we designate PH3 b, c, and
d, respectively. Furthermore, the middle planet, PH3 c, has a relatively low
density, g/cm for a planet of its mass, requiring a
substantial H/He atmosphere of by mass, and joins a
growing population of low-mass, low-density planets
Planet Hunters VII. Discovery of a New Low-Mass, Low-Density Planet (PH3 c) Orbiting Kepler-289 with Mass Measurements of Two Additional Planets (PH3 b and d)
We report the discovery of one newly confirmed planet ( days, ) and mass determinations of two previously validated Kepler planets, Kepler-289 b ( days, ) and Kepler-289-c ( days, ), through their transit timing variations (TTVs). We also exclude the possibility that these three planets reside in a Laplace resonance. The outer planet has very deep (), high signal-to-noise transits, which puts extremely tight constraints on its host star's stellar properties via Kepler's Third Law. The star PH3 is a young ( Gyr as determined by isochrones and gyrochronology), Sun-like star with , , and K. The middle planet's large TTV amplitude ( hours) resulted either in non-detections or inaccurate detections in previous searches. A strong chopping signal, a shorter period sinusoid in the TTVs, allows us to break the mass-eccentricity degeneracy and uniquely determine the masses of the inner, middle, and outer planets to be , , and , which we designate PH3 b, c, and d, respectively. Furthermore, the middle planet, PH3 c, has a relatively low density, g/cm for a planet of its mass, requiring a substantial H/He atmosphere of by mass, and joins a growing population of low-mass, low-density planets