Figure 3.
NGC 1277 and other
similar rotating, highdispersion, early-type
galaxies (red) are
consistent with the
M-sigma relation
(left), but appear to be
overluminous relative
to their black hole
mass (right).
more important. The team used these data
to determine a lower black hole mass — by a
factor of about three (4.9 x 109 MSun) — compared with earlier findings; still the black hole
at the heart of this galaxy remains one of the
most massive ever measured.
This result puts NGC 1277 well above the
standard relationship between black hole
mass and galaxy luminosity, placing it close
to the relationship between black hole mass
and bulge stellar velocity dispersion (the “Msigma relation”; Figure 3). These observations
and previous work identify NGC 1277 as a relic galaxy — one that has suffered only passive
evolution (the aging of stars) over time, rather
than the mergers and transformations that
result in giant elliptical galaxies in the nearby
Universe. Such relics offer windows into the
early Universe and galaxy formation.
Based on these results and similar examples, the authors suggest that black holes
formed first, followed by star formation, to
end up with galaxies that exhibit the usual
relations. The complete paper will be published in The Astrophysical Journal, and a
preprint is now available.
January 2016
October 2015
Best View of an Exoplanet Orbit
Observations using the Gemini
Planet Imager (GPI) provide images and polarization measurements of the β Pictoris (β Pic)
system that probe angular scales
smaller than ever before, from
ground or space (Figure 4). The
dynamical interactions of exoplanet β Pic b and a debris disk
offer tests of planet formation
models. A further advantage of
the new data is that they cover
observations of the disk and planet together
for more than a year, reducing errors in measurements of their relative positions.
Maxwell Millar-Blanchaer (University of Toronto) and colleagues use the polarimetric
observations especially to develop a model
for the disk itself. They show that the 10 - 12
MJup planet is not aligned with the largescale disk. Ten new astrometric measurements, obtained over a 14-month period
and combined with earlier data, yield the
planet’s orbital properties and the mass of
the central star accurately: 1.61 ± 0.05 MSun.
2015 Year in Review
GeminiFocus
Figure 4.
Polarization component
(Stokes I) of the β Pictoris
system. A purple x marks
the location of the star,
blocked by a mask in
the observation. The
horizontal dashed line
shows the position angle
of the outer disk. The
planet is separated from
the star by 0.4 arcseconds,
visible on the right side of
the image, offset above
the dashed line. This
image is 1.3 arcseconds
on a side.
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