Related papers: First Doppler image and starspot-corrected orbit f…

We publish 16 Doppler imaging temperature maps for the years 1994-2002 of the active RS CVn star II Peg. The six maps from 1999-2002 are based on previously unpublished observations. Through Doppler imaging we want to study the spot…

Brown dwarfs and planetary-mass companions display rotationally modulated photometric variability, especially those near the L/T transition. This variability is commonly attributed to top-of-atmosphere (TOA) inhomogeneities, with proposed…

Recent and upcoming stabilized spectrographs are pushing the frontier for Doppler spectroscopy to detect and characterize low-mass planets. Specifications for these instruments are so impressive that intrinsic stellar variability is…

We present the JHKs light curves for the double-lined eclipsing binary 2MASS J05352184-0546085, in which both components are brown dwarfs. We analyze these light curves with the published Ic-band light curve and radial velocities to provide…

Doppler spectroscopy has detected 136 planets around nearby stars. A major puzzle is why their orbits are highly eccentric, while all planets in our Solar System are on nearly circular orbits, as expected if they formed by accretion…

We present the first orbital elements for the massive close binary, HD 101131, one of the brightest objects in the young, open cluster, IC 2944. This system is a double-lined spectroscopic binary in an elliptical orbit with a period of…

Doppler Imaging (DI) is a well-established technique to map a physical field at a stellar surface from a time series of high-resolution spectra. In this proof-of-concept study, we aim to show that traditional DI algorithms, originally…

Large scale surveys of Andromeda's resolved stellar populations have revolutionized our view of this galaxy over the past decade. The combination of large-scale, contiguous photometric surveys and pointed spectroscopic surveys has been…

Future missions like Roman, HabEx, and LUVOIR will directly image exoplanets in reflected light. While current near infrared direct imaging searches are only sensitive to young, self-luminous planets whose brightness is independent of their…

Analytical relations are derived for the amplitude of astrometric, photometric and radial velocity perturbations caused by a single rotating spot. The relative power of the star spot jitter is estimated and compared with the available data…

ASAS photometric observations of LS 1135, an O-type SB1 binary system with an orbital period of 2.7 days, show that the system is also eclipsing. This prompted us to re-examine the spectra used in the previously published spectroscopic…

The LAMOST spectra and $\it{Kepler}$ light curves are combined to investigate the detached eclipsing binary KIC 8098300, which shows the O'Connell effect caused by spot/facula modulation. The radial velocity (RV) measurements are derived by…

BD And is a fairly bright (V = 10.8), active and close (P = 0.9258 days) eclipsing binary. The cyclic variability of the apparent orbital period as well as third light in the light curves indicate the presence of an additional late-type…

We present high precision radial velocity observations of HD17156 during a transit of its eccentric Jovian planet. In these data, we detect the Rossiter-McLaughlin effect, which is an apparent perturbation in the velocity of the star due to…

Andromeda XXI (And XXI) has been proposed as a dwarf spheroidal galaxy with a central dark matter density that is lower than expected in the Standard $\Lambda$ Cold Dark Matter ($\Lambda$CDM) cosmology. In this work, we present dynamical…

Double-lined spectroscopic orbital elements have recently been found for the central binary in the massive triple, delta Orionis A based on radial velocities from cross-correlation techniques applied to IUE high dispersion spectra and He I…

We report the discovery of a new relationship between a simple morphological characteristic of light curves produced by starspots and stellar rotation periods. The characteristic we examine is whether the light curve exhibits one dip or two…

Brightness variations due to dark spots on the stellar surface encode information about stellar surface rotation and magnetic activity. In this work, we analyze the Kepler long-cadence data of 26,521 main-sequence stars of spectral types M…

The Upsilon Andromedae system is the first exoplanetary system to have the relative inclination of two planets' orbital planes directly measured, and therefore offers our first window into the 3-dimensional configurations of planetary…

Extra-solar planet search programs require high-precision velocity measurements. They need to study how to disentangle radial-velocity variations due to Doppler motion from the noise induced by stellar activity. We monitored the active K2V…