Although our understanding of the star formation process has
seen great advances in the past two decades, our knowledge of details at
the lowest masses is still very limited. Two open questions are (1)
what is the low-mass cutoff for star formation, if there is one, and (2)
how frequently are these lowest mass objects formed? Through the
identification and analysis of low-mass stars and brown dwarfs in the
immediate Solar Neighborhood, we can provide the answers. Such a sample
also allows us to identify the nearest examples at each spectral
subclass to enable an eventual characterization of planetary systems as a
function of host "star" mass. The Wide-field Infrared Survey Explorer (WISE) is uniquely suited to providing this census down to temperatures much colder than any previous all-sky survey.
WISE is an Earth-orbiting NASA mission that surveyed the
entire sky at wavelengths of 3.4, 4.6, 12, and 22 μm. The 3.4- and
4.6-μm bands were specifically designed to probe the deep, 3.3-μm
methane absorption band in brown dwarfs and the region relatively free
of opacity near 4.6 μm. As such, WISE can readily identify the coldest
brown dwarfs by their 3.4-to-4.6 μm color, although its sensitivity and
full-sky coverage enable it to detect warmer brown dwarfs and low-mass
stars within (and in some cases, well beyond) the immediate Solar
Neighborhood. WISE has already begun to revolutionize our understanding
of the stellar census near the Sun via the discovery of a new
spectroscopic class, the Y dwarfs, and the identification of many new,
heretofore overlooked nearby objects.
As well suited as the WISE data are to nearby star detection,
observations at other wavelengths - usually in the near-infrared - are
crucial to verifying or rejecting candidates. Past, on-going, and future
investigations such as 2MASS, SDSS, UKIDSS, Pan-STARRS, VISTA,
SkyMapper, and LSST can provide the needed verification. Likewise, WISE
can provide the needed verification of candidates identified by those
surveys themselves. The time difference between WISE and these other
data sets also enables large-area proper motion searches at longer
wavelengths than were previously possible.
The WISE Science Team has already published 100 new brown dwarfs near the Sun, including the discovery of the first six Y dwarfs and the subsequent discovery of seven more.
Since the WISE Preliminary Data Release was made available to the
general public in April 2011, many papers by researchers not on the WISE
team have also been published. These include the proper motion discovery of nearby M and L dwarfs by comparing WISE data with those of 2MASS, the identification of other nearby L and T dwarf candidates using motion and color by comparing WISE data with 2MASS and SDSS, and the proper motion discovery of a nearby T8 dwarf by comparing WISE with 2MASS and Pan-STARRS data.
These first papers already highlight the variety of investigations
possible, and the early results provide strong hints that colder brown
dwarfs greatly outnumber their warmer counterparts. In fact, the WISE
data may not even be sensitive to the coldest (<200K) objects in the
Sun's vicinity, meaning that an even vaster reservoir of the coldest
brown dwarfs may remain out of reach.
A summary of results by the WISE brown dwarf team is already
included as an invited talk at this conference, so the goal of this splinter session to hear
from other groups. With the WISE Prelim Data Release and All-Sky Data Release already in the public domain, and the WISE 3-band cryo data scheduled for dissemination in late-June, 2012, we expect the low-mass star community to be teeming with new results and ideas.
The session will have six main talks of
15 minutes each with 5 minutes for a question and answer session
following each. Just before the coffee break, there will be a pop-up session wherein selected authors
have two minutes each to highlight the results of WISE-related posters.
- WELCOME: Davy Kirkpatrick, moderator
- SESSION 1: Mike Cushing, moderator
- Poster pop-up session:
- France Allard,
- "Models of VLMs, Brown Dwarfs and Planetary Mass Objects: Where are We Standing Today?"
- Karla Peña Ramírez,
- "Sigma Orionis: From 20M_sun to Free-floating Planets"
- Enrique Solano,
- "Discovering and Characterizing Very Low-mass Stars and Brown Dwarfs using Virtual Observatory Tools"
- David Pinfield,
- "Ultracool Benchmark Companions from a WISE+UKIDSS+VISTA View"
- Ralf-Dieter Scholz,
- "Proper Motions of 14 Known >T5 Dwarfs and Discovery of Three New T5.5-T6 Dwarfs from UKIDSS and Other Surveys"
- Jonathan Gagne,
- "Searching for Brown Dwarfs in Young Moving Groups"
- Chris Gelino,
- "Searching for Cold Companions to WISE Brown Dwarfs"
- 04:15-04:30 Coffee break
- SESSION 2: Chris Gelino, moderator
- Sandy Leggett, "Near-Infrared Photometric Followup of the WISE Y Dwarfs"