Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userA 2MASS L Dwarf Companion to the Nearby K Dwarf GJ 1048
97
0
0.0
(
0
)
Authors
John E. Gizis n IPAC/Caltech
Ask ChatGPT about the research
No Arabic abstract
We report the discovery of a probable L1 companion to the nearby K2 dwarf GJ 1048 using the Two Micron All-Sky Survey (2MASS). This source, 2MASSI J0235599-233120 or GJ 1048B, has 2MASS near-infrared colors and absolute magnitudes consistent with an early L dwarf companion with a projected separation of 250 A.U. The L1 spectral type is confirmed by far-red optical and low-resolution IR spectroscopy. We present evidence that GJ 1048 is a young (<~1 Gyr) system, and that GJ 1048B may be a high-mass brown dwarf below the hydrogen-burning limit. Additional studies of the GJ 1048 system will help constrain the characteristics of L dwarfs as a function of age and mass.
rate research
Read More
We present the discovery of a white dwarf companion at 3.6 from GJ3346, a nearby ($pisim$42 mas) K star observed with SPHERE@VLT as part of an open time survey for faint companions to objects with significant proper motion discrepancies ($Deltamu$) between Gaia DR1 and Tycho-2. Syrius-like systems like GJ3346AB, which include a main sequence star and a white dwarf, can be difficult to detect because of the intrinsic faintness of the latter. They have, however, been found to be common contaminants for direct imaging searches. White dwarfs have in fact similar brightness to sub-stellar companions in the infrared, while being much brighter in the visible bands like those used by Gaia. Combining our observations with Gaia DR2 and with several additional archival data sets, we were able to fully constrain the physical properties of GJ3346B, such as its effective temperature (11$times$10$^3pm$500 K) as well as the cooling age of the system (648$pm$58 Myrs). This allowed us to better understand the system history and to partially explains the discrepancies previously noted in the age indicators for this objects. Although further investigation is still needed, it seems that GJ3346, which was previously classified as young, is in fact most likely to be older than 4 Gyrs. Finally, given that the mass (0.58$pm$0.01$M_{odot}$)} and separation (85 au) of GJ3346B are compatible with the observed $Deltamu$, this discovery represents a further confirmation of the potential of this kind of dynamical signatures as selection methods for direct imaging surveys targeting faint, sub-stellar companions.
We confirm the substellar nature of ULAS J141623.94+134836.3, a common proper motion companion to the blue L dwarf SDSS J141624.08+134826.7 identified by Burningham et al. and Scholz. Low-resolution 0.8-2.4 micron spectroscopy obtained with IRTF/SpeX shows strong H2O and CH4 absorption bands, consistent with a T7.5 spectral type, and we see possible indications of NH3 absorption in the 1.0-1.3 micron region. More importantly, the spectrum of ULAS J1416+1348 shows a broadened Y-band peak and highly suppressed K-band flux, both indicative of high surface gravity and/or subsolar metallicity. These traits are verified through spectral model fits, from which we derive atmospheric parameters Teff = 650+/-60 K, log g = 5.2+/-0.4 cgs, [M/H] <= -0.3 and Kzz = 10^4 cm^2/s, the temperature being significantly warmer than that estimated by Burningham et al. These fits also indicate a model-dependent spectroscopic distance of 10.6(+3.0,-2.8) pc for ULAS J1416+1348, formally consistent with the 7.9+/-1.7 pc astrometric distance for SDSS J1416+1348 from Scholz. The common peculiarities of these two co-spatial, co-moving sources suggest that their unusual blue colors - and those of other blue L and T dwarfs in general - arise from age or metallicity, rather than cloud properties alone.
We report the detection of a planetary companion with a minimum mass of m sin i = 0.0771 M_Jup = 24.5 M_Earth to the nearby (d = 9.4 pc) M2.5V star GJ 176. The star was observed as part of our M dwarf planet search at the Hobby-Eberly Telescope (HET). The detection is based on 5 years of high-precision differential radial velocity (RV) measurements using the High-Resolution-Spectrograph (HRS). The orbital period of the planet is 10.24 d. GJ 176 thus joins the small (but increasing) sample of M dwarfs hosting short-periodic planets with minimum masses in the Neptune-mass range. Low mass planets could be relatively common around M dwarfs and the current detections might represent the tip of a rocky planet population.
The recent detection of circularly polarized, long-duration (>8 hr) low-frequency (~150 MHz) radio emission from the M4.5 dwarf GJ 1151 has been interpreted as arising from a star-planet interaction via the electron cyclotron maser instability. The existence or parameters of the proposed planets have not been determined. Using 20 new HARPS-N observations, we put 99th-percentile upper limits on the mass of any close companion to GJ 1151 at Msini < 5.6 M earth. With no stellar, brown dwarf, or giant planet companion likely in a close orbit, our data are consistent with detected radio emission emerging from a magnetic interaction between a short-period terrestrial-mass planet and GJ 1151.
We report the discovery of two binary M dwarf systems in the immediate solar neighborhood using 2MASS. The first is an M6.5 companion to the nearby G star HD 86728 (Gl 376). The known properties of HD 86728 indicate that the M dwarf (Gl 376B) is old, metal-rich and only 14.9 parsecs away. The M dwarf is highly active with both H alpha and X-ray emission. Thus, Gl 376B offers the opportunity to study an old, bright, active M dwarf with known metallicity, age, and luminosity. We show that it is probable that Gl 376B is itself an unresolved pair. The other system consists of an M6.5 and an M8 dwarf with 14.5 arcseconds separation. We estimate a distance of 16 parsecs for this very low mass pair. Stronger activity is observed in the M6.5 dwarf, supporting evidence that chromospheric activity is weakening near the hydrogen burning limit.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
