Bibcode
Mack, Claude E.; Ge, J.; Stassun, K.; Wisniewski, J.; Gaudi, S.; Fleming, S.; De Lee, N.; Lee, B.; Ghezzi, L.; Porto de Mello, G.; Ferreira, L.; Femenia, B.; Gonzalez-Hernandez, J.; Esposito, M.; Mahadevan, S.; Agol, E.; Tofflemire, B.; Beatty, T.; Eastman, J.; Hebb, L.; Pepper, J.; Cargile, P.; Paegert, M.; Siverd, R.
Bibliographical reference
American Astronomical Society, AAS Meeting #219, #439.09
Advertised on:
1
2012
Citations
0
Refereed citations
0
Description
The MARVELS (Multi-object APO Radial Velocity Large-area Survey) project
will monitor the radial velocities of 3300 stars. As a result, the
project is likely to find rare objects, such as brown dwarf (BD)
companions in the so-called brown dwarf desert. Two BD candidates in the
desert have already been uncovered by the survey. Until recently,
MARVELS Candidate 10 (MC10) appeared to be yet another candidate for the
desert. The RV data seemed to neatly fit an eccentric orbit with a
237-day period and a minimum mass of 50 Jupiter masses. However, there
were two anomalous points in the RV follow-up,
which were initially rejected because they were thought to be a result
of changes with the instrument. Then it was discovered that the original
MARVELS data possessed similar anomalous points which had also been
excluded as outliers. A thorough re-examination of the cross-correlation
functions (CCFs) in both data sets revealed that the two anomalous
points in the follow-up data had double-peaked CCFs, and the MARVELS
data showed CCFs that seemed too broad compared to the other MARVELS
candidates. This led to the conclusion that MC10 is most likely an
eccentric spectroscopic binary with the long axis aligned nearly
perpendicular to the line of sight. Therefore, it is only for a brief
moment near periastron that the two radial velocities are large and
disparate enough to be resolved as a double-peaked CCF. This cautionary
tale implies that RV searches for substellar companions must ensure full
phase coverage, and must carefully examine how the CCF changes with
time, in order to avoid this kind of astrophysical false positive.