Sky and Telescope - October 2015 - 29

DIGITIZED SKY SURVEY 2

T. PILLAI & J. KAUFFMAN, SOURCES: SPITZER
GLIMPSE & MIPSGAL IMAGES, CSO HERTZ DATA

"Brick"
Galactic Center
50 light-years

T. PILLAI & J. KAUFFMAN, SOURCES:
SPITZER GLIMPSE & MIPSGAL IMAGES,
JCMT SCUPOL DATA

BRICK & SNAKE Two dense molecular clouds known as the
Brick (top) and the Snake (bottom) show up as dark shadows in
Spitzer images (left), silhouetted against a background of midinfrared emission from warm dust and gas. But the clouds glow
at submillimeter (top right) and far-infrared wavelengths (bottom
right). The polarization of this long-wavelength radiation showed
Pillai's team how the magnetic ﬁeld is oriented: parallel to the
Brick ﬁlament and perpendicular to the Snake ﬁlament.

IN ANOTHER
LIGHT
The L1495/B213
ﬁlaments of cold,
dense gas are
just shadows in
the visible-light
Digitized Sky
Survey image
(above), but they
glow gently at
submillimeter
wavelengths
(left).

ESO / APEX / A. HACAR ET AL. / DIGITIZED SKY SURVEY 2

isn't to say measurements are impossible: for example,
strong magnetic ﬁelds can split a spectral line into
multiple lines at slightly diﬀerent wavelengths (known as
the Zeeman eﬀect), and the direction of a cloud's magnetic ﬁeld will inﬂuence the polarization of light passing
through it, which astronomers can then measure.
The problem is that magnetic ﬁelds suﬀ use the
sparse gas that ﬂoats between stars and star-forming
clouds. In that drifting, low-density gas, the magnetic
ﬁeld is weak but well aligned. So if astronomers observe
the magnetic ﬁeld in a collapsing cloud, their view
would also include the gas between Earth and the cloud.
Chances are this interstellar gas will dominate their
measurements and perhaps even give a false sense of
what the magnetic ﬁeld looks like within the cloud.
But astronomers never shy away from a challenge.
Thushara Pillai (Max Planck Institute for Radio Astronomy, Germany) and colleagues zeroed in on two of
the darkest infrared shadows along the galactic plane.
Dubbed the Brick and the Snake, these clouds lie 12,000
and 27,000 light-years from Earth, respectively.
Though the shadows are dark in the infrared, they
glow gently at even longer wavelengths. Dust grains, especially well-aligned ones on the clouds' surfaces, polarize
this radiation as it escapes. Pillai's team used archival data
from the James Clerk Maxwell Telescope and the Caltech

"Snake"

30 light-years

Sk yandTelescope.com October 2015

29

http://www.SkyandTelescope.com

Sky and Telescope - October 2015

Table of Contents for the Digital Edition of Sky and Telescope - October 2015

Contents
Sky and Telescope - October 2015 - Cover1
Sky and Telescope - October 2015 - Cover2
Sky and Telescope - October 2015 - 1
Sky and Telescope - October 2015 - Contents
Sky and Telescope - October 2015 - 3
Sky and Telescope - October 2015 - A
Sky and Telescope - October 2015 - B
Sky and Telescope - October 2015 - 4
Sky and Telescope - October 2015 - 5
Sky and Telescope - October 2015 - 6
Sky and Telescope - October 2015 - 7
Sky and Telescope - October 2015 - 8
Sky and Telescope - October 2015 - 9
Sky and Telescope - October 2015 - 10
Sky and Telescope - October 2015 - 11
Sky and Telescope - October 2015 - 12
Sky and Telescope - October 2015 - 13
Sky and Telescope - October 2015 - 14
Sky and Telescope - October 2015 - 15
Sky and Telescope - October 2015 - 16
Sky and Telescope - October 2015 - 17
Sky and Telescope - October 2015 - 18
Sky and Telescope - October 2015 - 19
Sky and Telescope - October 2015 - 20
Sky and Telescope - October 2015 - 21
Sky and Telescope - October 2015 - 22
Sky and Telescope - October 2015 - 23
Sky and Telescope - October 2015 - 24
Sky and Telescope - October 2015 - 25
Sky and Telescope - October 2015 - 26
Sky and Telescope - October 2015 - 27
Sky and Telescope - October 2015 - 28
Sky and Telescope - October 2015 - 29
Sky and Telescope - October 2015 - 30
Sky and Telescope - October 2015 - 31
Sky and Telescope - October 2015 - 32
Sky and Telescope - October 2015 - 33
Sky and Telescope - October 2015 - 34
Sky and Telescope - October 2015 - 35
Sky and Telescope - October 2015 - 36
Sky and Telescope - October 2015 - 37
Sky and Telescope - October 2015 - 38
Sky and Telescope - October 2015 - 39
Sky and Telescope - October 2015 - 40
Sky and Telescope - October 2015 - 41
Sky and Telescope - October 2015 - 42
Sky and Telescope - October 2015 - 43
Sky and Telescope - October 2015 - 44
Sky and Telescope - October 2015 - 45
Sky and Telescope - October 2015 - 46
Sky and Telescope - October 2015 - 47
Sky and Telescope - October 2015 - 48
Sky and Telescope - October 2015 - 49
Sky and Telescope - October 2015 - 50
Sky and Telescope - October 2015 - 51
Sky and Telescope - October 2015 - 52
Sky and Telescope - October 2015 - 53
Sky and Telescope - October 2015 - 54
Sky and Telescope - October 2015 - 55
Sky and Telescope - October 2015 - 56
Sky and Telescope - October 2015 - 57
Sky and Telescope - October 2015 - 58
Sky and Telescope - October 2015 - 59
Sky and Telescope - October 2015 - 60
Sky and Telescope - October 2015 - 61
Sky and Telescope - October 2015 - 62
Sky and Telescope - October 2015 - 63
Sky and Telescope - October 2015 - 64
Sky and Telescope - October 2015 - 65
Sky and Telescope - October 2015 - 66
Sky and Telescope - October 2015 - 67
Sky and Telescope - October 2015 - 68
Sky and Telescope - October 2015 - 69
Sky and Telescope - October 2015 - 70
Sky and Telescope - October 2015 - 71
Sky and Telescope - October 2015 - 72
Sky and Telescope - October 2015 - 73
Sky and Telescope - October 2015 - 74
Sky and Telescope - October 2015 - 75
Sky and Telescope - October 2015 - 76
Sky and Telescope - October 2015 - 77
Sky and Telescope - October 2015 - 78
Sky and Telescope - October 2015 - 79
Sky and Telescope - October 2015 - 80
Sky and Telescope - October 2015 - 81
Sky and Telescope - October 2015 - 82
Sky and Telescope - October 2015 - 83
Sky and Telescope - October 2015 - 84
Sky and Telescope - October 2015 - Cover3
Sky and Telescope - October 2015 - Cover4
https://www.nxtbook.com/nxtbooks/aas/st_202406
https://www.nxtbook.com/nxtbooks/aas/st_202405
https://www.nxtbook.com/nxtbooks/aas/st_202404_qr
https://www.nxtbook.com/nxtbooks/aas/st_202404
https://www.nxtbook.com/nxtbooks/aas/st_202403
https://www.nxtbook.com/nxtbooks/aas/st_202402
https://www.nxtbook.com/nxtbooks/aas/st_202401_aus
https://www.nxtbook.com/nxtbooks/aas/st_202401
https://www.nxtbook.com/nxtbooks/aas/st_202312_aus
https://www.nxtbook.com/nxtbooks/aas/st_202312
https://www.nxtbook.com/nxtbooks/aas/st_202311
https://www.nxtbook.com/nxtbooks/aas/st_202310
https://www.nxtbook.com/nxtbooks/aas/st_202309
https://www.nxtbook.com/nxtbooks/aas/st_202308
https://www.nxtbook.com/nxtbooks/aas/st_202307
https://www.nxtbook.com/nxtbooks/aas/st_202306
https://www.nxtbook.com/nxtbooks/aas/st_202305
https://www.nxtbook.com/nxtbooks/aas/st_202304
https://www.nxtbook.com/nxtbooks/aas/st_202304_qr
https://www.nxtbook.com/nxtbooks/aas/st_202303
https://www.nxtbook.com/nxtbooks/aas/st_202302
https://www.nxtbook.com/nxtbooks/aas/st_202301
https://www.nxtbook.com/nxtbooks/aas/st_202212
https://www.nxtbook.com/nxtbooks/aas/st_202211
https://www.nxtbook.com/nxtbooks/aas/st_202210
https://www.nxtbook.com/nxtbooks/aas/st_202209
https://www.nxtbook.com/nxtbooks/aas/st_202208
https://www.nxtbook.com/nxtbooks/aas/st_202207
https://www.nxtbook.com/nxtbooks/aas/st_202206
https://www.nxtbook.com/nxtbooks/aas/st_202205
https://www.nxtbook.com/nxtbooks/aas/st_202204
https://www.nxtbook.com/nxtbooks/aas/st_202203
https://www.nxtbook.com/nxtbooks/aas/st_202202
https://www.nxtbook.com/nxtbooks/aas/st_202201
https://www.nxtbook.com/nxtbooks/aas/st_202112
https://www.nxtbook.com/nxtbooks/aas/st_202111
https://www.nxtbook.com/nxtbooks/aas/st_202110
https://www.nxtbook.com/nxtbooks/aas/st_202109
https://www.nxtbook.com/nxtbooks/aas/st_202108
https://www.nxtbook.com/nxtbooks/aas/st_202107
https://www.nxtbook.com/nxtbooks/aas/st_202106
https://www.nxtbook.com/nxtbooks/aas/st_202105
https://www.nxtbook.com/nxtbooks/aas/st_202104
https://www.nxtbook.com/nxtbooks/aas/st_202103
https://www.nxtbook.com/nxtbooks/aas/st_202102
https://www.nxtbook.com/nxtbooks/aas/st_202101
https://www.nxtbook.com/nxtbooks/aas/skywatch_2021
https://www.nxtbook.com/nxtbooks/aas/st_202012
https://www.nxtbook.com/nxtbooks/aas/st_202011
https://www.nxtbook.com/nxtbooks/aas/st_202010
https://www.nxtbook.com/nxtbooks/aas/st_202009
https://www.nxtbook.com/nxtbooks/aas/st_202008
https://www.nxtbook.com/nxtbooks/aas/st_202007
https://www.nxtbook.com/nxtbooks/aas/st_202006
https://www.nxtbook.com/nxtbooks/aas/st_202005
https://www.nxtbook.com/nxtbooks/aas/st_202004
https://www.nxtbook.com/nxtbooks/aas/st_202003
https://www.nxtbook.com/nxtbooks/aas/st_202002
https://www.nxtbook.com/nxtbooks/aas/st_202001
https://www.nxtbook.com/nxtbooks/aas/st_201912
https://www.nxtbook.com/nxtbooks/aas/st_201911
https://www.nxtbook.com/nxtbooks/aas/st_201910
https://www.nxtbook.com/nxtbooks/aas/st_201909
https://www.nxtbook.com/nxtbooks/aas/st_201908
https://www.nxtbook.com/nxtbooks/aas/st_201907
https://www.nxtbook.com/nxtbooks/aas/st_201906
https://www.nxtbook.com/nxtbooks/aas/st_201905
https://www.nxtbook.com/nxtbooks/aas/st_201904
https://www.nxtbook.com/nxtbooks/aas/st_201903
https://www.nxtbook.com/nxtbooks/aas/st_201902
https://www.nxtbook.com/nxtbooks/aas/st_201901
https://www.nxtbook.com/nxtbooks/aas/st_201812
https://www.nxtbook.com/nxtbooks/aas/st_201811
https://www.nxtbook.com/nxtbooks/aas/st_201810
https://www.nxtbook.com/nxtbooks/aas/st_201809
https://www.nxtbook.com/nxtbooks/aas/st_201808
https://www.nxtbook.com/nxtbooks/aas/st_201807
https://www.nxtbook.com/nxtbooks/aas/st_201806
https://www.nxtbook.com/nxtbooks/aas/st_201805
https://www.nxtbook.com/nxtbooks/aas/st_201804
https://www.nxtbook.com/nxtbooks/aas/st_201803
https://www.nxtbook.com/nxtbooks/aas/st_201802
https://www.nxtbook.com/nxtbooks/aas/st_201801
https://www.nxtbook.com/nxtbooks/aas/st_201712
https://www.nxtbook.com/nxtbooks/aas/st_201711
https://www.nxtbook.com/nxtbooks/aas/st_201710
https://www.nxtbook.com/nxtbooks/aas/st_201709
https://www.nxtbook.com/nxtbooks/aas/st_201708
https://www.nxtbook.com/nxtbooks/aas/st_201707
https://www.nxtbook.com/nxtbooks/aas/st_201706
https://www.nxtbook.com/nxtbooks/aas/st_201705
https://www.nxtbook.com/nxtbooks/aas/st_201704
https://www.nxtbook.com/nxtbooks/aas/st_201703
https://www.nxtbook.com/nxtbooks/aas/st_201702
https://www.nxtbook.com/nxtbooks/aas/st_201701
https://www.nxtbook.com/nxtbooks/aas/st_201612
https://www.nxtbook.com/nxtbooks/aas/st_201611
https://www.nxtbook.com/nxtbooks/aas/st_201610
https://www.nxtbook.com/nxtbooks/aas/st_201609
https://www.nxtbook.com/nxtbooks/aas/st_201608
https://www.nxtbook.com/nxtbooks/aas/st_201607
https://www.nxtbook.com/nxtbooks/aas/st_201606
https://www.nxtbook.com/nxtbooks/aas/st_201605
https://www.nxtbook.com/nxtbooks/aas/st_201604
https://www.nxtbook.com/nxtbooks/aas/st_201603
https://www.nxtbook.com/nxtbooks/aas/st_201602
https://www.nxtbook.com/nxtbooks/aas/st_201601
https://www.nxtbook.com/nxtbooks/aas/st_201512
https://www.nxtbook.com/nxtbooks/aas/st_201511
https://www.nxtbook.com/nxtbooks/aas/st_201510
https://www.nxtbook.com/nxtbooks/aas/st_201509
https://www.nxtbook.com/nxtbooks/aas/st_201508
https://www.nxtbook.com/nxtbooks/aas/st_201507
https://www.nxtbook.com/nxtbooks/aas/st_201506
https://www.nxtbook.com/nxtbooks/aas/st_201505
https://www.nxtbook.com/nxtbooks/aas/st_201504
https://www.nxtbook.com/nxtbooks/aas/st_201503
https://www.nxtbook.com/nxtbooks/aas/st_201502
https://www.nxtbook.com/nxtbooks/aas/st_201501
https://www.nxtbook.com/nxtbooks/aas/st_201412
https://www.nxtbook.com/nxtbooks/aas/st_201411
https://www.nxtbook.com/nxtbooks/aas/st_201410
https://www.nxtbook.com/nxtbooks/aas/st_201409
https://www.nxtbook.com/nxtbooks/aas/st_201408
https://www.nxtbook.com/nxtbooks/aas/st_201407
https://www.nxtbook.com/nxtbooks/aas/st_201406
https://www.nxtbook.com/nxtbooks/aas/st_mars
https://www.nxtbook.com/nxtbooks/aas/st_201405
https://www.nxtbook.com/nxtbooks/aas/st_201404
https://www.nxtbook.com/nxtbooks/aas/st_201403
https://www.nxtbook.com/nxtbooks/aas/st_201402
https://www.nxtbook.com/nxtbooks/aas/st_201401
https://www.nxtbook.com/nxtbooks/aas/st_201312
https://www.nxtbook.com/nxtbooks/aas/st_201311
https://www.nxtbook.com/nxtbooks/aas/st_201310
https://www.nxtbook.com/nxtbooks/aas/st_201309
https://www.nxtbook.com/nxtbooks/aas/st_201308
https://www.nxtbook.com/nxtbooks/aas/st_201307
https://www.nxtbook.com/nxtbooks/aas/st_201306
https://www.nxtbook.com/nxtbooks/aas/st_201305
https://www.nxtbook.com/nxtbooks/aas/st_201304
https://www.nxtbook.com/nxtbooks/aas/st_201303
https://www.nxtbook.com/nxtbooks/aas/st_201302
https://www.nxtbook.com/nxtbooks/aas/st_201301
https://www.nxtbook.com/nxtbooks/aas/st_201212
https://www.nxtbook.com/nxtbooks/aas/st_201211
https://www.nxtbook.com/nxtbooks/aas/st_201210
https://www.nxtbook.com/nxtbooks/aas/st_201209
https://www.nxtbook.com/nxtbooks/aas/st_201208
https://www.nxtbook.com/nxtbooks/aas/st_201207
https://www.nxtbook.com/nxtbooks/aas/st_201206
https://www.nxtbook.com/nxtbooks/aas/st_201205
https://www.nxtbook.com/nxtbooks/aas/st_201204
https://www.nxtbook.com/nxtbooks/aas/st_201203
https://www.nxtbook.com/nxtbooks/aas/st_201202
https://www.nxtbook.com/nxtbooks/aas/st_201201
https://www.nxtbook.com/nxtbooks/aas/st_201112
https://www.nxtbook.com/nxtbooks/aas/st_201111
https://www.nxtbook.com/nxtbooks/aas/st_201110
https://www.nxtbook.com/nxtbooks/aas/st_201109
https://www.nxtbook.com/nxtbooks/aas/st_201108
https://www.nxtbook.com/nxtbooks/aas/st_201107
https://www.nxtbook.com/nxtbooks/aas/st_201106
https://www.nxtbook.com/nxtbooks/aas/st_201105
https://www.nxtbook.com/nxtbooks/aas/st_201104
https://www.nxtbook.com/nxtbooks/aas/st_201103
https://www.nxtbook.com/nxtbooks/aas/st_201102
https://www.nxtbook.com/nxtbooks/aas/st_201101
https://www.nxtbook.com/nxtbooks/aas/st_201012
https://www.nxtbook.com/nxtbooks/aas/st_201011
https://www.nxtbook.com/nxtbooks/aas/st_201010
https://www.nxtbook.com/nxtbooks/aas/st_201009
https://www.nxtbook.com/nxtbooks/aas/st_201008
https://www.nxtbook.com/nxtbooks/aas/st_201007
https://www.nxtbook.com/nxtbooks/aas/st_201006
https://www.nxtbook.com/nxtbooks/aas/st_201005
https://www.nxtbook.com/nxtbooks/aas/st_201004
https://www.nxtbook.com/nxtbooks/aas/st_201003
https://www.nxtbook.com/nxtbooks/aas/st_201002
https://www.nxtbook.com/nxtbooks/aas/st_201001
https://www.nxtbookmedia.com