[Nessc] NESSC meeting 27 on the outer heliosphere and the interstellar interaction

Thu Nov 22 08:46:28 EST 2018

Phil,
One way you look at your data is to make contour plots. Ideally, there are 3 basic situations: circles, ellipses, and eggs. Circles are obviously symmetric. An ellipse has a  long axis and a shorter one. The long axis direction is what I said “enhancement direction” in my previous email. If the long axis is vertical or horizontal, you are seeing the heliospheric field effects. If the axis is significantly different from these two directions, it should be controlled by the ISM field direction. Eggs include some secondary effects or when both field effects are of the similar strength. Also if the center is off the nose, there is a systematic process that needs to be figured out.
Of course the real data is very complicated. If you cannot show clear asymmetry in these contours, or if it is too complicated to categorize, I do not think you can draw any significant conclusion. The signal of the effect, although theoretically valid, for this effect is too weak to sense. However, you can continue find clever ways to reduce the noise level and eventually the signature becomes obvious to everyone.
Paul
P.s. Concerning the usage of “single piece of information”, it sounds like that I insulted many people. But I am learning philosophy with Eberhart. Philosophically, it is only one thing, I.e. Asymmetry, that you are trying to show, if neglecting the technical details.

From: Philip Isenberg <phil.isenberg at unh.edu<mailto:phil.isenberg at unh.edu>>
Date: Wed, Nov 21, 18 at 6:11 PM
To: "Song, Paul" <Paul_Song at uml.edu<mailto:Paul_Song at uml.edu>>
Cc: Nathan Schwadron <nschwadron at guero.sr.unh.edu<mailto:nschwadron at guero.sr.unh.edu>>, NESSC NESSC <nessc at lists.sr.unh.edu<mailto:nessc at lists.sr.unh.edu>>
Subject: Re: [Nessc] NESSC meeting 27 on the outer heliosphere and the interstellar interaction

Hi Paul:

I am trying to follow your thoughts here, and I apologize if I’ve misinterpreted them.  Your view of potential asymmetries seems fine as far as it goes, but it seems to me that you may be neglecting something.  The angle between the ISM flow and the ISM field need not be (and probably isn’t) either zero or 90 degrees.  If this angle is between these two, this by itself can result in a further asymmetry independent of the solar effects.  Certainly, given spherically symmetric solar influence, the heliopause should be symmetric transverse to the plane containing both the interstellar field and flow vectors.  This was realized a long time ago.  However, even in this simple case, it need not be symmetric about the nose in the directions along the field.  Thus, the HP may be “fatter” on one side than the other.

It may be that your magnetospheric experience is leading you astray, since in that case the SW flow is strongly dominant and the field angle does not affect the large-scale magnetosheath structure very much.

I do not agree that these maps constitute a single observation (even in the steady state limit).  The various fluxes entering the instrument sample the outer heliosheath plasma flow in a complicated, but specifically limited, way.  Thus, they can actually tell us something about the detailed spatial structure of the interstellar flow field.  It is not a single-point measurement.

Happy Thanksgiving to you too.

Regards,
Phil

On Nov 21, 2018, at 11:56 AM, Song, Paul <Paul_Song at uml.edu<mailto:Paul_Song at uml.edu>> wrote:

Phil and Harald ,
I assume that this email can reach both of you. if not, Nathan, could you forward to them?
I am following the discussion we had on using the secondary He to probe the outer heliosheath, a very interesting idea.
I repeat my comment that the observation shows only (possible) asymmetry of the sheath flow. This is a new (and single) piece of information. One should not use it to resolve more than one unknown. Otherwise it is over-interpretation of observation, a common mistake in today’s data analyses. Any model that is used in the deriving the data cannot be used to confirmed the model unless there is independent validation of the model. This was my comment of one can solve only one unknown from one equation.

With that said, I am following Phil’s idea. If there were no ISM magnetic field and the solar magnetic field, the flow around a body could be assumed as axial symmetric. The asymmetry observed can be caused by one or both magnetic fields. As I mentioned during the discussion, the ISM field effect tends to enhance the flow around the nose in the two tangential directions perpendicular to the ISM field. therefore, the asymmetry can be potentially used to infer the direction of the ISM field. in this case, one may not be able to infer the shape of the heliosphere. The solar magnetic field, on the other hand, tends to produce asymmetry relative to the dipole tilt, assuming to be north-south. In which direction enhancement can be seen depends on the heliospheric model. If the heliosphere is fatter in the flank, enhancement should be seen in the azimuthal direction. if the heliosphere is skinny as shown in Merav’s simulation, the enhancements should be in the latitudinal direction. The asymmetry can be compared with the these two field directions to determine which one is dominant. My feeling is that the ISM field most likely to be dominant.

Happy Holiday!
Paul

From: Nessc <nessc-bounces at lists.sr.unh.edu<mailto:nessc-bounces at lists.sr.unh.edu>> On Behalf Of Nathan Schwadron
Sent: Saturday, October 6, 2018 6:24 PM
To: NESSC NESSC <nessc at lists.sr.unh.edu<mailto:nessc at lists.sr.unh.edu>>
Subject: [Nessc] NESSC meeting 27 on the outer heliosphere and the interstellar interaction

Announcing ..

NESSC meeting 27 on the outer heliosphere and the interstellar interaction
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Monday November 19, 2018, 10 AM – 5 PM
U Mass Lowell, UCC Building, Room UCC-158
Parking is across in the Salem St. lot

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Local Organizers:
Ofer Cohen <ofer_cohen at uml dot edu>
Paul Song <Paul_Song at uml dot edu>

NESSC Organizers:
Nathan Schwadron <nschwadron at unh dot edu>
Merav Opher <mopher at bu dot edu>

Web Organizer:
Ken Fairchild  <Ken.Fairchild at unh dot edu>

Over the last decade, observations from the Voyager Satellites, the Interstellar Boundary Explorer, and Cassini/INCA have ushered in an era of discovery concerning the previously unknown properties of the global heliosphere and its interaction with the local interstellar medium. Wide ranging observations including those of pickup ions, anomalous cosmic rays and suprathermal particles have significant implications for our understanding of global interstellar interactions.

This 27th meeting of the New England Space Science Consortium includes topics concerning the global heliosphere, the local interstellar medium, interstellar interactions, and related topics.  As always, we invite all members of the New England Space Science community to the meeting. And as in all meetings, we will include contributions from participants on wide-ranging topics.

Speakers Include:
Merav Opher  (BU) - Global Heliosphere Simulations
Paul Song (UML) – Analytical Approach to Interstellar Boundary Structure
Adam Michaels (BU) – Simulations of the Global Heliosphere
Marc Kornbleuth (BU) – Simulations of the Global Heliosphere
Ofer Cohen (UML) – Modeling of the Heliosphere and Astrospheres
Fatemeh Rahmanifard (UNH) — Interstellar Neutral H from IBEX
Eberhard Moebius (UNH) — Interstellar Neutral Atoms from IBEX and IMAP
Marty Lee (UNH)— Analytical Model of Interstellar Neutral Atoms
Nathan Schwadron  (UNH) — IBEX observations of the Ribbon and Globally Distributed Flux over 9 years
Harald Kucharek (UNH) – Secondary Neutral Atoms Observed by IBEX
Phil Isenberg (UNH) – Analytical Modeling of Secondary Neutral Atoms Observed by IBEX

CHeers

 Nathan

Nathan Schwadron
Presidential Chair
Norman S. and Anna Marie Waite Professor
University of New Hampshire

n.schwadron at unh.edu<mailto:n.schwadron at unh.edu>
Morse Hall - Room 350
8 College Road
Durham NH 03824
USA

(603) 862-3451

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