星形成ゼミ
2021/12/03
SFN 347 #7-#12

長谷川哲夫

1

347 The SEDIGISM survey: The in uence of spiral arms on the molecular gas distribution of the inner#7 Milky Way
arXiv:2110.06071v1, Accepted for publication in A&A

The SEDIGISM survey: The influence of spiral arms on the molecular gas distributionof the inner Milky Way

D. Colombo, A. Duarte-Cabral, A. R. Pettitt, J. S. Urquhart, F. Wyrowski, T. Csengeri, K. R. Neralwar, F.
Schuller, K. M. Menten, L. Anderson, P. Barnes, H. Beuther, L. Bronfman, D. Eden, A. Ginsburg, T. Henning,
C. Koenig, M. -Y. Lee, M. Mattern, S. Medina, S. E. Ragan, A. J. Rigby, A. Sanchez-Monge, A. Traficante, A.
Y. Yang, M. Wienen F The morphology of the Milky Way is still a matter of debate. In order to shed light on uncertainties
surrounding the structure of the Galaxy, in this paper, we study the imprint of spiral arms on the distribution and properties of
its molecular gas. To do so, we take full advantage of the SEDIGISM survey that observed a large area of the inner Galaxy inthe 13 CO(2-1) line at an angular resolution of 28". We analyse the influences of the spiral arms by considering the features ofthe molecular gas emission as a whole across the longitude-velocity map built from the full survey. Additionally, we examine theproperties of the molecular clouds in the spiral arms compared to the properties of their counterparts in the inter-arm regions.
Through flux and luminosity probability distribution functions, we find that the molecular gas emission associated with thespiral arms does not diﬀer significantly from the emission between the arms. On average, spiral arms show masses per unit
length of ⇠ 105 106 M kpc 1 . This is similar to values inferred from data sets in which emission distributions were segmented
into molecular clouds. By examining the cloud distribution across the Galactic plane, we infer that the molecular mass in the
spiral arms is a factor of 1.5 higher than that of the inter-arm medium, similar to what is found for other spiral galaxies in thelocal Universe. We observe that only the distributions of cloud mass surface densities and aspect ratio in the spiral arms show
significant diﬀerences compared to those of the inter-arm medium; other observed diﬀerences appear instead to be driven by adistance bias. By comparing our results with simulations and observations of nearby galaxies, we conclude that the measured
quantities would classify the Milky Way as a flocculent spiral galaxy, rather than as a grand-design one.

Discs and outflows in the early phases of massive star formation: influence of magnetic
SEDIGISMdiﬀusion(Structure, Excitation, and Dynamics of the Inner Galactic
fields and ambipolarflBenoît Commerçon,
Matthias
González,survey
Raphaël Mignon-Risse, Patrick Hennebelle, Neil Vaytet F We study
Interstellar
Medium)mass accretion and ejection in the vicinity of massive star forming cores using high-resolution (5 au) 3D AMR numerical• APEX (12m)
simulations. We investigate the mechanisms at the origin of outflows and characterise the properties of the disc forming around
13CO both
massive protostars.
We include
protostellar
radiative
feedback
evolutionary
and magnetic ambipolar• DR1:
J=2-1,
L= -60 to+18 deg,|B|via< PMS
0.5 deg(+sometracks
small
diﬀusion. We studied 3 diﬀerent cases: purely hydrodynamical, ideal MHD, and ambipolar diﬀusion. In the resistive models, we
extentions), FWHM = 28”, RMS = 0.8-1 K Tmbhave on the properties of the massive protostellar
investigate the eﬀects the initial amplitude of both magnetic field and rotation2
system. We use simple criteria to identify the outflow and disc material and follow their evolution as the central star accretes
mass up to 20 solar mass. The outflow is completely diﬀerent when magnetic fields are introduced, so that magnetic processes

Fig. 1. From top to bottom: Longitude–velocity map (l3-map) from the trunk-masked full survey data cube (see Section 2), the cloud data cube, thedata cube obtained for the clouds located in the spiral arms, and the data cube obtained for the clouds located in the inter-arms (following the CxyA
method described in Section 4.2.2). In each panel, the spiral arm tracks defined by Taylor & Cordes (1993) are overlaid: the 3 kpc arms in magenta,
the Norma-Outer arm in red, the Scutum-Centaurus arm in blue, the Sagittarius-Carina arm in green, and the Perseus arm in yellow. Dotted blacklines surround areas of the lv map that have a velocity o↵set with respect to the spiral arms within 10 km s 1 . Shaded patches indicate regions
along the spiral arms where the velocity di↵erence between adjacent arms (along the velocity axis) is greater than 20 km s 1 . In the last two panels,
the clouds associated with the 3 kpc arms and the clouds with unreliable distance are excluded as they cannot be unequivocally associated with aspiral arm or inter-arm region (see Section 4.2.2).

3

Fig. 2. Face-on view of the Galactic region surveyed by SEDIGISM (confined within the dotted lines; top panels) overlaid with spiral arm tracks
defined by TC93: the 3 kpc arms in magenta, the Norma-Outer arm in red, the Scutum-Centaurus arm in blue, the Sagittarius-Carina arm in green,
and the Perseus arm in yellow (the solid lines merely trace the bottom of the potential, and do not correspond to a real ‘thickness’). The positionof the Sun is indicated with a green circle, while the Galactic centre is shown with a green ‘X’. In the top-left panel, coloured dots represent the
number density distribution of all molecular clouds identified within the SEDIGISM field by DC21. The top-right and bottom panels show the
distribution of the clouds in the full sample with respect to the spiral arms in xy and lv space, respectively. Clouds are colour-encoded by theattributed spiral arm. Objects in the inter-arm region are in cyan and clouds with uncertain allocation are shown in grey. The latter consist of clouds
associated with the 3 kpc arms and those with unreliable distances.

4

D. Colombo, A. Duarte-Cabral, A. R. Pettitt et al.: SEDIGISM spiral arms

Fig. 6. Top left: Probability distribution functions (PDFs) of the integrated intensity emission for the full integrated intensity map (black), within
the spiral arms (red), for inter-arm regions (blue), and towards the Galactic centre (green). Top middle: PDFs normalised by the total counts (N) in
the distribution. Top right: Relative value of the normalised PDFs of each region with respect to the normalised total distribution (named ‘All’ inthe left panel). In the top-left panel legend, IDI median (µ) and median absolute deviation ( ) are shown for each region (where SA, IA, and GC
stand for spiral arms, inter-arm region, and Galactic centre, respectively). The IDI thresholds are indicated with grey vertical dotted lines. Bottom
row: Parallel distribution representations using CO luminosity from clouds. Statistics for the LDI from each considered region are indicated in thebottom-left panel legend.

method, we built the luminosity PDFs considering the cloud association from the CxyA method. Given the constraints of the

could assume the distance errors of the clouds (from DC21) as
the dominant uncertainty in the calculation of the CO luminosity

5

A&A proofs: manuscript no. main_corr
Table 2. Summary of the numbers and densities of the molecular ISM and clouds within given locations across the Galactic disc.

Property(1)log(Mfull )lengthlog(Mfull /length)
Ncloudlog(Mcloud )lengthNcloud /lengthlog(Mcloud /length)
Ncloudlog(Mcloud )lengthNcloud /lengthlog(Mcloud /length)
lengthwidthQ50 (widthIQR )area
NcloudNcloud /arealog(Mcloud )log(Mcloud /area)

Units
(2)

3 kpc Nor-Out
Scu-Cen
Sag-Car
Perseus
(3)
(4)
(5)
(6)
(7)
Fl3A method: non-overlapping spiral arm segments
M
6.07
6.47
6.43
3.88
6.51
kpc
7.67
4.04
9.27
9.28
3.05
M kpc 1 5.19
5.87
5.46
2.92
6.02
CxyA method: non-overlapping spiral arm segments
308
455
32
35
M
6.32
6.19
3.84
5.47
kpc
4.04
9.27
9.28
3.05
kpc 1
75.85
48.98
3.46
11.48
M kpc 1
5.72
5.22
2.87
4.99
CxyA method: full spiral arm extent
943
1742
543
263
M
6.69
6.83
6.38
6.13
kpc
16.92
27.23
22.13
4.01
kpc 1
56.23
64.57
24.55
66.07
M kpc 1
5.46
5.40
5.03
5.53
kpc
16.92
27.23
22.13
4.01
pc
463 (666) 531 (810) 951 (952) 682 (885)
kpc2
7.84
14.48
21.06
2.74
943
1742
543
263
kpc 2
120.23120.23
25.70
95.50
M
6.69
6.83
6.38
6.13
M kpc 2
5.80
5.67
5.05
5.70

Spiral arms
(8)

Inter-arm(9)7.00/6.95
33.32/25.65
5.48/5.54

-

830
6.59
33.32
25.12
5.07

-

3491
7.19
70.29
50.12
5.34
70.29
579 (832)
46.12
3491
75.86
7.19
5.53

2973
7.01
51.35
2973
57.54
7.01
5.30

Notes. From left to right. Column (1): considered property: mass of the molecular ISM calculated from the l3-map (Mfull ), length of the spiralarm or spiral arm segment across the SEDIGISM field (length), mass of the molecular ISM per unit length (of a spiral arm segment, Mfull /length),
number of clouds (Ncloud ), mass in clouds Mcloud , number of clouds per unit length (of a spiral arm/spiral arm segment, Ncloud /length), mass inclouds per unit length (of a spiral arm/spiral arm segment, Mcloud /length), medians (widthQ50 ) and inter-quartile ranges (widthIQR ) of two times theabsolute o↵set with respect to the spiral-arm ridge line, length of the spiral arms multiplied by the median width (area), cloud number surface
density (Ncloud /area), and cloud mass surface density (Mcloud /area). Column (2): considered property units. Columns (3)-(7): spiral arm or spiralarm segment name. Column (8): entire spiral-arm region, the symbol ‘/’ separates quantities calculated with the 3 kpc arms contribution included
and excluded, respectively. Column (9): entire inter-arm region. Quantities are calculated following the Fl3A method (Section 4.1) and CxyA
method (Section 4.2) considering the non-overlapping segment on the l3-map (see Figure 1), and for the CxyA method also the extent of the fullarm.

6

significant diﬀerences compared to those of the inter-arm medium; other observed diﬀerences appear instead to be driven by adistance bias. By comparing our results with simulations and observations of nearby galaxies, we conclude that the measured
and out ows in the early phases of massive star formation: in uence of magnetic elds and
347 Discs
quantities
would classify the Milky Way as a flocculent spiral galaxy, rather than as a grand-design one.

#8

ambipolar diffusion

arXiv:2109.10580v1,
for publicationin A&A
Discs andoutflows in accepted
the early
phases of
massive star formation: influence of magnetic
fields and ambipolar diﬀusionBenoît Commerçon, Matthias González, Raphaël Mignon-Risse, Patrick Hennebelle, Neil Vaytet F We study
mass accretion and ejection in the vicinity of massive star forming cores using high-resolution (5 au) 3D AMR numericalsimulations. We investigate the mechanisms at the origin of outflows and characterise the properties of the disc forming aroundmassive protostars. We include both protostellar radiative feedback via PMS evolutionary tracks and magnetic ambipolar
diﬀusion. We studied 3 diﬀerent cases: purely hydrodynamical, ideal MHD, and ambipolar diﬀusion. In the resistive models, weinvestigate the eﬀects the initial amplitude of both magnetic field and rotation have on the properties of the massive protostellar
system. We use simple criteria to identify the outflow and disc material and follow their evolution as the central star accretes
mass up to 20 solar mass. The outflow is completely diﬀerent when magnetic fields are introduced, so that magnetic processes
are the main driver of the outflow up to stellar masses of 20 solar mass. The disc properties depend on the physics included.
The disc formed in the ideal and resistive runs show opposite properties in terms of plasma beta and of magnetic fields topology.
While the disc in the ideal case is dominated by the magnetic pressure and the toroidal magnetic fields, the one formed in theresistive runs is dominated by the thermal pressure and has essentially vertical magnetic fields in the inner regions (R<200au). We find that magnetic processes dominate the early evolution of massive protostellar systems (<20 solar mass) and shapes
the accretion/ejection as well as the disc formation. Ambipolar diﬀusion is mainly at work at disc scales and regulates its
properties. Our finding for the outflow and disc properties are reminiscent of low-mass star formation, suggesting that accretionand ejection in young massive and low-mass protostars are regulated by the same physical processes at the early stages.

Gas dynamics in the star forming region G18.148 0.283: Is it a manifestation of twocolliding molecular clouds?

fi

fl

fl

Jyotirmoy Dey, Jagadheep D. Pandian, Dharam Vir Lal F We report the results obtained from a multi-wavelength studyof the HII region, G18.148 0.283, using the upgraded Giant Metre-wave Radio Telescope (uGMRT) at 1350 MHz along withother archival data. In addition to the radio continuum emission, we have detected the H169↵ and H170↵ radio recombinationlines towards G18.148 0.283 using a correlator bandwidth of 100 MHz. The moment-1 map of the ionized gas reveals a velocity
gradient of approximately 10 km s 1 across the radio continuum peaks. The 12 CO (J=3 2) molecular line data from the
COHRS survey also shows the presence of two velocity components that are very close to the velocities detected in the ionizedgas. The spectrum and position-velocity diagram from CO emission reveal molecular gas at an intermediate velocity range
bridging the velocity components. We see mid-infrared absorption and far-infrared emission establishing the presence of afilamentary infrared dark cloud, the extent of which includes the targeted HII region. The magnetic field inferred from7 dust
polarization is perpendicular to the filament within the HII region. We have also identified two O9 stars and 30 young stellar

the accretion/ejection as well as the disc formation. Ambipolar diﬀusion is mainly at work at disc scales and regulates its
properties.
Ourfinding forin
theoutflowand disc propertiesare reminiscent of Is
low-massstar formation,ofsuggestingthat accretion
dynamics
thestar forming
region G18.148−0.283:
it a manifestation
two colliding
347 Gasand ejection in young massive and low-mass protostars are regulated by the same physical processes at the early stages.

#9

molecular clouds?

arXiv:2111.07977v1,
Accepted
publication inregion
The AstrophysicalJournal 0.283: Is it a manifestation of two
Gas dynamics
in thestarforforming
G18.148colliding molecular clouds?

Jyotirmoy Dey, Jagadheep D. Pandian, Dharam Vir Lal F We report the results obtained from a multi-wavelength studyof the HII region, G18.148 0.283, using the upgraded Giant Metre-wave Radio Telescope (uGMRT) at 1350 MHz along withother archival data. In addition to the radio continuum emission, we have detected the H169↵ and H170↵ radio recombinationlines towards G18.148 0.283 using a correlator bandwidth of 100 MHz. The moment-1 map of the ionized gas reveals a velocity
gradient of approximately 10 km s 1 across the radio continuum peaks. The 12 CO (J=3 2) molecular line data from the
COHRS survey also shows the presence of two velocity components that are very close to the velocities detected in the ionizedgas. The spectrum and position-velocity diagram from CO emission reveal molecular gas at an intermediate velocity range
bridging the velocity components. We see mid-infrared absorption and far-infrared emission establishing the presence of afilamentary infrared dark cloud, the extent of which includes the targeted HII region. The magnetic field inferred from dust
polarization is perpendicular to the filament within the HII region. We have also identified two O9 stars and 30 young stellar
objects towards the target using data from the 2MASS, UKIDSS, and GLIMPSE surveys. Cumulatively, this suggests that theregion is the site of a cloud-cloud collision that has triggered massive star formation and subsequent formation of an HII region.

48

347 The formation of massive stellar clusters in converging galactic ows with photoionisation#10 arXiv:2110.09201v1, 2022MNRAS.509..954D

The formation of massive stellar clusters in converging galactic flows with photoionisation

C. L. Dobbs, T. J. R. Bending, A. R. Pettitt, M. R. Bate F We have performed simulations of cluster formation
along two regions of a spiral arm taken from a global Milky Way simulation, including photoionising feedback. One region ischaracterised by strongly converging flows, the other represents a more typical spiral arm region. We find that more massive
clusters are able to form on shorter timescales for the region with strongly converging flows. Mergers between clusters are
frequent in the case of the strongly converging flows and enable the formation of massive clusters. We compare equivalentclusters formed in simulations with and without ionisation. Photoionisation does not prevent massive cluster formation, but
can be seen to limit the masses of the clusters. On average the mass is reduced by around 20%, but we see a large spread fromionisation having minimal diﬀerence to leading to a 50% reduction in mass. Photoionisation is also able to clear out the gas in
the vicinity of the clusters on Myr timescales, which can produce clusters with larger radii that are surrounded by more massive
stellar halos. We find that the ionising feedback has more impact in our second region which is less dense and has less strongly
converging flows.

Phase space analysis of the young stellar component of the Radcliﬀe Wave

J. Donada, F. Figueras F The Radcliﬀe Wave is a galactic-scale structure recently proposed by J. Alves et al. (2019).
The authors propose that various molecular complexes in the solar environment follow a specific alignment and displacementthat make them worthy of a common origin and evolution. In this work, we first collected and analyzed the population ofvery young stars and open clusters around this structure. The criteria for cross-matching these star-forming tracers with theidentified Radcliﬀe Wave cloud complexes have been defined and applied, all based on the quality of the available astrometricand photometric data. We performed a first characterization of the structure and kinematic properties of the young stellar
population linked to this wave. Our conclusions, although verypreliminary, are: 1) we have identified 13 open clusters, eachof them physically linked to a Cloud Complex, which are probable members of the Radcliﬀe Wave; 2) The OB field stars do
not present the elongated structure that departs from an straight line at the Sun position observed in the Cloud Complexes; 3)
the vertical motion of 11 CC-OCs members associated with the Wave is not contradictory with the behaviour expected from a
simple model of harmonic motion in the vertical direction, and 4) the orbits back on time neither suggest an origin associatedto a point nor to a straight line in the XZ plane.

Testing the Potential for Radio Variability in Disks around T Tauri Stars with Obser9
vations and Chemical Modelingfl

C. C. Espaillat, E. Macias, J. Wendeborn, R. Franco-Hernandez, N. Calvet, A. Rilinger, L. I. Cleeves, P.

the vicinity of the clusters on Myr timescales, which can produce clusters with larger radii that are surrounded by more massive
Phase
analysisof thefeedback
younghasstellarofsecond
the Radcliffe
WavestellarWespacefind thatthe ionising
morecomponent
impact in our
region whichis less dense and has less strongly
347 halos.
converging flows.
#11 arXiv:2111.04685v1

Phase space analysis of the young stellar component of the Radcliﬀe Wave

J. Donada, F. Figueras F The Radcliﬀe Wave is a galactic-scale structure recently proposed by J. Alves et al. (2019).
The authors propose that various molecular complexes in the solar environment follow a specific alignment and displacementthat make them worthy of a common origin and evolution. In this work, we first collected and analyzed the population ofvery young stars and open clusters around this structure. The criteria for cross-matching these star-forming tracers with theidentified Radcliﬀe Wave cloud complexes have been defined and applied, all based on the quality of the available astrometricand photometric data. We performed a first characterization of the structure and kinematic properties of the young stellar
population linked to this wave. Our conclusions, although verypreliminary, are: 1) we have identified 13 open clusters, eachof them physically linked to a Cloud Complex, which are probable members of the Radcliﬀe Wave; 2) The OB field stars do
not present the elongated structure that departs from an straight line at the Sun position observed in the Cloud Complexes; 3)
the vertical motion of 11 CC-OCs members associated with the Wave is not contradictory with the behaviour expected from a
simple model of harmonic motion in the vertical direction, and 4) the orbits back on time neither suggest an origin associatedto a point nor to a straight line in the XZ plane.

Testing the Potential for Radio Variability in Disks around T Tauri Stars with Observations and Chemical Modeling

C. C. Espaillat, E. Macias, J. Wendeborn, R. Franco-Hernandez, N. Calvet, A. Rilinger, L. I. Cleeves, P.
D’Alessio F A multiwavelength observing campaign of the T Tauri star (TTS) GM Aur was undertaken in 2019 Decemberthat obtained Swift X-ray and NUV fluxes, HST NUV spectra, LCOGT ugri and TESS photometry, CHIRON Halpha spectra,
ALMA 13CO and C18O line fluxes, and VLA 3 cm continuum fluxes taken contemporaneously over one month. The X-ray
to optical observations were presented previously. Here we present the ALMA and VLA data and make comparisons to GM
Aur’s accretion and X-ray properties. We report no variability in the observed millimeter CO emission. Using disk chemistrymodels, we show that the magnitude of the changes seen in the FUV luminosity of GM Aur could lead to variation of up to
6% in CO line emission and changes in the X-ray luminosity could lead to larger changes of 25%. However, the FUV and
X-ray luminosity increases must last at least 100 years in order to induce changes, which seems implausible in the TTS stage;also, these changes would be too small to be detectable by ALMA. We report no variability in the 3 cm emission observed by
the VLA, showing that changes of less than a factor of 3 in the accretion rates of TTSs do not lead to detectable changes in
the mass-loss rate traced by the jet at centimeter wavelengths. We conclude that typically seen changes in the FUV and X-ray
luminosities of TTSs do not lead to observable changes in millimeter CO line emission or jet centimeter continuum emission.
10

OB stars(P-G+)OB stars(Xu+)
3

FIG. 1: XY map of the Radcli↵e Wave tracers (left column) and their same map with the cloud complexes of Alveset al. catalogue ([4]) overplotted as red points (right column). The top panel corresponds to the open clusters inCastro-Ginard et al. catalogue ([8]) younger than 30Myr, and the mid and bottom panels are the density maps of
the OB stellar population: the mid panel corresponds to the Pantaleoni-González et al. OB stars catalogue ([7],using the distances estimated with J. Maı́z Apellániz’s Bayesian formalism: [13] and [14]), and the bottom panel
corresponds to the Xu et al. OB stars catalogue ([5]). The straight inclined grey lines delineate a region containing
the Radcli↵e Wave. Both lines are parallel and tilted 30º relative to the Y axis in the first galactic quadrant, one
passing through the Sun’s position (origin) and the other being horizontally translated 600pc to the left.

Open Clusters(Age < 30 Myr)Cloud Complexes

11

CCs

Phase space analysis of the young stellar component of the Radcli↵e Wave

OC-CC couples

model for the Milky Way’s gravitational potential. It
is a 3D axisymmetric potential composed by a spherical bulge, a Miyamoto-Nagai potential for the disk and a
NFW (Navarro-Frenk-White) potential for the dark matter halo.
The orbit integration for the RW tracers needs to go backin time, after the established initial conditions, only up
to few tens of Myr, the maximum quantity assumed for
the Radcli↵e Wave’s age. We want to emphasize that inthis so short a time a linear trace-back on time using thecurrent velocity vector would be almost equivalent. The
galpy package for orbit integration has been used here
only to get familiarized with the code, although it is notstrictly necessary for the study.

(a)OC-CC couples in RW
IV.

FIG. 3: All points are positions of OCs younger than
30Myr which have a CC at less than 150pc. The ones
centred in green circles correspond to physically coupledpairs of one OC and one CC. Among these, the 13 inred colour are paired OC-CC which belong to the region
where the Radcli↵e wave is defined. A few distantoutliers have been left out of the figure.

belonging to the RW is obtained. Their location is shownin Fig. 3. As the kinematic data are available for theOCs, by means of their orbit integration the movementof their associated Radcli↵e Wave’s cloud complexes canalso be traced.

Vzのパタンはあまり調B.

Trace-back orbital analysis

和振動子っぽくはない

We want to characterize not only the spatial distribution of the Radcli↵e Wave, but also its dynamical evolution. With that, we aim to evaluate whether its constituents really describe a spatially and kinematically coherent structure.
In order to trace back the orbit of the RW tracers,
the Python galpy package for galactic dynamics is used.
Providing the initial ra, dec, distance, proper motion in
ra and in dec, and the heliocentric line-of-sight velocity, it provides the Galactocentric-Cartesian coordinates
X, Y , and Z as well as their respective velocities VX ,VY , and VZ at any time of the orbit integrated in a certain Galactic potential. For this first study, the chosen potential has been MWPotential2014 ([9]), a simple（否定も肯定もせず）[14] Output Galactic coordinates of the Galpy code: X axis is in the
Sun - Galactic center direction, centered at the Galactic Centerand positive toward the Galactic Anticenter; Y axis positive toward the Galactic rotation and Z perpendicular to the Galactic
plane

RESULTS

In order to visualize the undulation of the RW structure traced by the 13 OC-CC pairs identified in Fig. 3,
an axis yprime is defined as follows:
yprime = y cos(30 ) + x sin(30 )(1)Where (x, y, z) are the heliocentric Galactic coordinates
and the yprime axis corresponds to the straight line passing through the Sun’s position in Fig. 1, and is approximately lined up with the RW structure in the first andsecond galactic quadrants, as done in Alves et al. paper ([4]). As mentioned in Sect. II D, the inclination of(b)
the RW could di↵er in the third Galactic quadrant withrespect to what is observed in the first and second quadrants. This misalignment is not considered here for two
reasons. Firstly, we want to reproduce Alves et al. ([4])
paper’s steps as much as possible, and secondly, a change
in the inclination just at the Sun location is suspicious,
why just at Sun’s location?
In Fig. 4 (mid panel) we present the distribution of the
13 selected CC-OC pairs in the (yprime , z) plane, i.e., approximately along the RW structure. This figure bears a
close resemblance to Fig. 2 in Alves et al. paper ([4]),reproduced in the top panel in Fig. 4 for comparison.
We observe that the 13 CCs which have been found tobe linked to a young OC are quite uniformly distributed
along the wave. Although this small number of objects
has very little statistical significance, from now on we willassume that this small sample is an acceptable representation of the CCs defining the RW.
Out of this sample of 13 OC-CC pairs belonging to the
Radcli↵e Wave, the radial velocity is known for 11 OCs.
In Fig. 4 (bottom panel) we plotted with black arrows the(c)velocity component perpendicular to the Galactic plane(VZ ) of these CC-OC pairs. From a simple model of harFIG.
4: motion(a): theRWverticalas publishedby should
Alvesexpect
et al. [4] (see their Fig. 2 for explanation). (b): the RW as seen by cloudmonic
in thedirection wecomplexes
young
open
clusters.
lighttheblue points are all the local cloud complexes in Alves et al. catalogue
a maximumand
velocityof theparticles
whenThecrossing
plane
and Amongan almostnull verticalat theposi-belong to the RW and have an associated OC, whose position is([4]).
these,
the 13velocity
with redcirclestions
of maximum
thatis, when
the aresepararepresented
as aelongation,
dark blue
point(thesethe 13 OC-CC pairs identified in Fig. 3). (c): The Galactic velocitytion from the z = 0 plane is maximum. Observing theVz (arrows)

12

perpendicular to the Galactic plane (VZ ) for the 11 OC-CC pairs is shown as black arrows (see text for explanation).

銀河面

子午面

5 Myr ago
10 Myr ago
20 Myr ago
(a)

(b)

FIG. 5: Orbital motion of the 11 OC-CC pairs belonging to the Radcli↵e Wave identified in Fig. 3 and highlighted
in Fig. 4 (b). The black arrows represent the current velocity vector of the OC of each pair. Each curve describes
the orbit of an OC-CC pair, highlighted in di↵erent colours as a function of time: the yellow part corresponds to the
trajectory from the present to 5Myr ago, the orange part corresponds to the trajectory comprised between 5Myrand 10Myr ago, and the gray part corresponds to the trajectory comprised between 10Myr and 20Myr ago. (a):projection on the Galactic plane, with the galactic center located at (X, Y ) = (0, 0) kpc and the Sun at(X, Y ) = (8.0, 0) kpc (b): projection on the (X, Z) meridional plane.

Orion region (X, Y) = (8.3, -0.07) という例外はあるが、V. CONCLUSIONS AND WORK IN PROGRESSThe orbit integration back in time for the 11 CC-OC
pairs is presented in Fig. 5. We show both, the projected orbit in the galactic plane (left panel) and on thevertical meridional plane (right panel). As described in
Sect. III B, the MWPotential2014 potential has beenused in this trace-back orbital analysis. As expected,
the orbits of some of the CC-OC pairs seem to have acommon origin. This is the case of the OC-CC pairs as-

一般的傾向として、RW全体にわたる共通の起源（過去にある一点
In this work we present a first attempt to characterize the stellar component of the Radcli↵e Wave. We
have considered as tracers the most updated cataloguesof young open clusters and the OB field stars, both withaccurate Gaia DR2 and eDR3 data. As expected, thelocation of the young open clusters with ages up to 30で誕生した）を示唆する証拠は見られない

13

Nature 578, 237 (2020)
A Galactic-scale gas wave in the Solar Neighborhood

25. Goodman, A. A. et al. The bones of the milky way. Astrophys. J. 797, 53 (2014).
26. W.-T. Kim, C.-G.1,2
K. & Ostriker, E. C. Astrophys. J.3in prep (2019).

João Alves , Catherine Zucker , Alyssa A. Goodman2,3, Joshua S. Speagle3, Stefan Meingast1,
4
3,5
RobitailleDouglasP.Y.Finkbeiner, infrared
EdwardSchlafly6, and Gregory M. Green7
27. Thomas
Elmegreen, B.
G., Elmegreen,, D.
M. & Efremov,
N. Regularly spaced
peaksF.
in thedusty spirals of messier 100. Astrophys. J. 863 (2018).
1

University
Vienna, Department
of inAstrophysics,
Türkenschanzstrasse
28. Edelsohn,
D. J.of& Elmegreen,
B. G. Corrugations
galactic discs generated
by magellanic-type 17, 1180 Wien, Austria
2
perturbers.
Mon. Not.
R. Astron.
287, 947–954(1997).Harvard University, 10 Garden Street, Cambridge, MA 02138, USA
Radcliffe
InstituteforSoc.
Advanced
Study,
3

HarvardL.University
Astronomy,
Centerspiralfor galaxy
Astrophysics
29. Matthews,
D. & Uson, J.Department
M. Corrugationsof
in thedisk of the Edge-On
IC 2233. | Harvard & Smithsonian, 60 Garden St.
Cambridge,
MA02138, USA
Astrophys.
J. 688, 237(2008).
4

Aperio Software, Headingley Enterprise & Arts Centre, Bennett Road, Leeds LS6 3HN, UK

30. 5 Bally, J. Overview of the orion complex. Handbook of Star Forming Regions 64, 459–370
Harvard University Department of Physics, 17 Oxford Street, Cambridge, MA 02138, USA(2008).
6
7

Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305, USA

For the past 150 years, the prevailing view of the local Interstellar Medium (ISM) was based ona peculiarity known as the Gould’s Belt1, 2, 3, 4, an expanding ring of young stars, gas, and dust,
tilted about 20∘ to the Galactic plane. Still, the physical relation between local gas clouds hasremained practically unknown because the distance accuracy to clouds is of the same order
or larger than their sizes5, 6, 7. With the advent of large photometric surveys8 and the Gaia
satellite astrometric survey9 this situation has changed10. Here we report the 3-D structure of
all local cloud complexes. We find a narrow and coherent 2.7 kpc arrangement of dense gas in
the Solar neighborhood that contains many of the clouds thought to be associated with theGould Belt. This finding is inconsistent with the notion that these clouds are part of a ring,
Figure 2:the
3-D majority
distribution of of
local
clouds. The
position of the Sun is marked with a ⊙. The size of the
disputing the Gould Belt model. The new structure comprises
nearbystarsymbols is proportional to column density. The red points were selected by a fitting algorithm, as
forming regions, has an aspect ratio of about 1:20, and contains
3 million
solar
massesdescribed inabout
the Supplementary
methods
section.
These describe a spatially and kinematicallyFigure 1: Sky map of targeted star forming regions towards the anti-center of the Milky Way. The
coherent structure
we term
Radcliffe Wave (possiblemodels are shown in black in the bottomfilledof
circles
represent
the studied lines theof sight
used todetermine accurate
distances toto knowngas.
Remarkably,newstructureappears
be undulating
and its
3-Dthedistribution
is wellright). The grayscale on the XY panel show an integrated dust map (-300 < Z < 300 pc), thatnearby star-forming complexes (the regions labels are roughly proportional to distance). The open
described
a dampedsinusoidal
wave
on the
plane
Milky
with
an average
period complete. To highlight the undulation
indicatesthat Way,
our sample
of clouds
distances is essentiallycircles
represent lines byof sight
toward lower column
density envelopes
betweencomplexes.
The of the
backgroundgrayscale
map
shows
the
columndensity
distribution
derivedfrom
Planckdata.
andco-planarity
ofthestructure,
the
right
panelsshow inprojections in which the XY frame has beenof about 2 kpc and a maximum amplitude of about 160 pc. Our results represent
a first step
rotated anticlockwise by 33∘ (top) and clockwise 120∘ (bottom) for an observer facing the Galactic
the revision of the local gas distribution and Galactic structure
anda new,
broaderanti-center.
The offer
1σ statisticaluncertainties(usually 1 - 2% in distance) are represented by line
segments,
which
areusuallysmallerthan the symbols. There is an additional systematic uncertainty
context to studies on the transformation of molecular gas into stars.
17

14

which is estimated to be ≈ 5% in distance10. For an interactive version of this figure, including extra
layers not shown here (e.g. model of the Gould’s Belt, log-spiral arm fits), see
https://faun.rc.fas.harvard.edu/czucker/Paper_Figures/radwave.html.
To reveal the physical connections between clouds in the local
ISM, we determined the 3-D

distribution of all local clouds complexes11 by deriving accurate distances to 380 lines of sight. Thelines of sight were chosen to include not only all known local Methods
clouds10, 12 but also potential bridges

14the vertical motion of 11 CC-OCs members associated with the Wave is not contradictory with the behaviour expected from a
simple modelof harmonic
motionforin theverticaldirection,in
and4) thearoundorbits backon timeneitheran originandassociatedthe Potential
Radio
Variability
Disks
T TauriStars
with suggest
Observations
347 Testing
to a point nor to a straight line in the XZ plane.

#11 Chemical Modeling

arXiv:2111.02454v1,
accepted
ApJ
Testing
the Potential
for byRadio
Variability in Disks around T Tauri Stars with Observations and Chemical Modeling

C. C. Espaillat, E. Macias, J. Wendeborn, R. Franco-Hernandez, N. Calvet, A. Rilinger, L. I. Cleeves, P.
D’Alessio F A multiwavelength observing campaign of the T Tauri star (TTS) GM Aur was undertaken in 2019 Decemberthat obtained Swift X-ray and NUV fluxes, HST NUV spectra, LCOGT ugri and TESS photometry, CHIRON Halpha spectra,
ALMA 13CO and C18O line fluxes, and VLA 3 cm continuum fluxes taken contemporaneously over one month. The X-ray
to optical observations were presented previously. Here we present the ALMA and VLA data and make comparisons to GM
Aur’s accretion and X-ray properties. We report no variability in the observed millimeter CO emission. Using disk chemistrymodels, we show that the magnitude of the changes seen in the FUV luminosity of GM Aur could lead to variation of up to
6% in CO line emission and changes in the X-ray luminosity could lead to larger changes of 25%. However, the FUV and
X-ray luminosity increases must last at least 100 years in order to induce changes, which seems implausible in the TTS stage;also, these changes would be too small to be detectable by ALMA. We report no variability in the 3 cm emission observed by
the VLA, showing that changes of less than a factor of 3 in the accretion rates of TTSs do not lead to detectable changes in
the mass-loss rate traced by the jet at centimeter wavelengths. We conclude that typically seen changes in the FUV and X-ray
luminosities of TTSs do not lead to observable changes in millimeter CO line emission or jet centimeter continuum emission.

The Eﬀects of Starspots on Spectroscopic Mass Estimates of Low-mass Young Stars

C. Flores, M. S. Connelley, B. Reipurth, G. Duchêne F Magnetic fields and mass accretion processes create dark andbright spots on the surface of young stars. These spots manifest as surface thermal inhomogeneities, which alter the global
temperature measured on the stars. To understand the eﬀects and implications of these starspots, we conducted a large iSHELL
high-resolution infrared spectroscopic survey of T Tauri stars in Taurus-Auriga and Ophiuchus star-forming regions. From the
K band spectra, we measured stellar temperatures and magnetic field strengths using a magnetic radiative transfer code.
We compared our infrared-derived parameters against literature optical temperatures and found a) a systematic temperature
diﬀerence between optical and infrared observations, and b) a positive correlation between the magnetic field strengths andthe temperature diﬀerences. The discrepant temperature measurements imply significant diﬀerences in the inferred stellar
masses from stellar evolutionary models. To discern which temperature better predicts the mass of the star, we compared ourmodel-derived masses against dynamical masses measured from ALMA and PdBI for a sub-sample of our sources. From thiscomparison we conclude that, in the range of stellar masses from 0.3 to 1.3 M , neither infrared nor optical temperatures
perfectly reproduce the stellar dynamical masses. But, on average, infrared temperatures produce more precise and accurate15