Transit Search for Exoplanets around Alpha Centauri A and B with ASTERIA

Abstract

Alpha Centauri is a triple star system with two Sun-like stars, α Cen A (V = 0.01) and B (V = 1.33), and a third fainter red dwarf star, Proxima Centauri. Most current transit missions cannot produce precision photometry of α Cen A and B as their detectors saturate for these very bright stars. The Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA) was a technology demonstration mission that successfully demonstrated two key technologies necessary for precision photometry achieving line-of-sight fine-pointing stability of 0.5″ rms and focal plane temperature control of ±0.01 K over a period of 20 minutes. The payload consisted of a 6.7 cm aperture diameter refractive camera and used a scientific complementary metal-oxide semiconductor detector that enabled monitoring of the brightest stars without saturating. We obtained spatially unresolved (blended) observations of α Cen A and B during opportunistic science campaigns as part of ASTERIA's extended mission. The resulting 1σ photometric precision for the blended α Cen A and B data is 250 ppm (parts per million) per 9 s exposure. We do not find evidence of transits in the blended data. We establish limits for transiting exoplanets around both α Cen A and B using transit signal injection and recovery tests. We find that ASTERIA is sensitive to planets with radii as small as 3.0 R ⊕ around α Cen A and 3.7 R ⊕ around α Cen B, corresponding to signals of ∼500 ppm (signal-tonoise ratio = 5.0) in the blended data, with periods ranging from 0.5 to 6 days.

Compressive Sensing Based Space Flight Instrument Constellation for Measuring Gravitational Microlensing Parallax

“…In our simulations, we assume the number of satellites in the constellation to be [0, n sat ], where the maximum number is n sat = 8. A detector concept for placing a telescope on a Small Satellite can be based off of ASTE-RIA (Arcsecond Space Telescope Enabling Research in Astrophysics) [20]. ASTERIA is a 6U CubeSat with a telescope aperture of 6.7 cm with a CMOS detector of 2592 × 2192 pixels.…”

“…We vary Φ, the space-flight instrument orbital phase to span over a range of values of δ τ and δ β . Our microlensing parallax, π E , is given by Equation (20). From [8], we make the same assumptions of the source being located in the galactic bulge at 4 kpc, lens at 8 kpc with a relative lens-source speed of 200 km/s to obtain the value of π E .…”

“…We can use Equations ( 11) and ( 13) with the given value for π E in Equation (20). Our simulations vary the value of R and Φ to determine the effect of CS reconstruction on photometric curves with a microlensing parallax.…”