Hubble search for planets around Proxima Centauri using microlensing

View previous topic View next topic Go down

Hubble search for planets around Proxima Centauri using microlensing

Post by jyril on 3rd June 2013, 12:03 pm

Hubble Press Release: Rare Stellar Alignment Offers Opportunity to Hunt for Planets

The ancients thought that stars were fixed pinpoints of light on the sky. Today we know that they are all moving, like fish in a pond. This so-called proper motion is so small that it is not noticeable to the human eye over a single lifetime. But Hubble can precisely track stellar motions to razor-sharp precision. Not surprisingly the nearest star to our Sun, Proxima Centauri, is one of the fastest moving across the sky. Hubble astronomers have found that it will pass in front of two far-more distant background stars, once in 2014 and again in 2016. This will afford a very rare opportunity to see how Proxima's gravity warps the image of the background stars by bending their light. This effect, called gravitational lensing, can be used to estimate Proxima Centauri's mass and establish the presence of any planets orbiting the star.

_________________
The universe is not only stranger than we imagine, it is stranger than we can imagine.
avatar
jyril
Planetesimal
Planetesimal

Number of posts : 133
Registration date : 2008-06-09

View user profile

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by Edasich on 3rd June 2013, 12:15 pm

I just look forward Very Happy
avatar
Edasich
dM star
dM star

Number of posts : 1510
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

View user profile

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by Lazarus on 3rd June 2013, 1:16 pm

Does this actually count as "microlensing" or is it more strictly speaking "mesolensing"? I've seen the latter term used for lensing events associated with nearby stars.
avatar
Lazarus
dG star
dG star

Number of posts : 2822
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by Stalker on 3rd June 2013, 1:29 pm

Yes i think, like the events predicted for VB10

_________________
avatar
Stalker
Jovian
Jovian

Number of posts : 526
Age : 26
Location : Paris, France
Registration date : 2008-06-16

View user profile http://exoplanetes.wetpaint.com/

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by Sirius_Alpha on 2nd January 2014, 9:24 pm

Microlensing Events by Proxima Centauri in 2014 and 2016: Opportunities for Mass Determination and Possible Planet Detection
http://arxiv.org/abs/1401.0239

We have found that Proxima Centauri, the star closest to our Sun, will pass close to a pair of faint background stars in the next few years. Using Hubble Space Telescope (HST) images obtained in 2012 October, we determine that the passage close to a mag 20 star will occur in 2014 October (impact parameter 1.6"), and to a mag 19.5 star in 2016 February (impact parameter 0.5"). As Proxima passes in front of these stars, the relativistic deflection of light will cause shifts in the positions of the background stars by ~0.5 and 1.5 mas, respectively, readily detectable by HST imaging, and possibly by Gaia and ground-based facilities such as VLT. Measurement of these astrometric shifts offers a unique and direct method to measure the mass of Proxima. Moreover, if Proxima has a planetary system, the planets may be detectable through their additional microlensing signals, although the probability of such detections is small. With astrometric accuracies of 0.03 mas (achievable with HST spatial scanning), centroid shifts caused by Jovian planets are detectable at separations of up to 2.0" (corresponding to 2.6 AU at the distance of Proxima), and centroid shifts by Earth-mass planets are detectable within a small band of 8 mas (corresponding to 0.01 AU) around the source trajectories. Jovian planets within a band of about 28 mas (corresponding to 0.036 AU) around the source trajectories would produce a brightening of the source by >0.01 mag and could hence be detectable. Estimated timescales of the astrometric and photometric microlensing events due to a planet range from a few hours to a few days, and both methods would provide direct measurements of the planetary mass.

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3468
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by Edasich on 3rd January 2014, 5:24 am

We just have to wait October for earliest results.
avatar
Edasich
dM star
dM star

Number of posts : 1510
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

View user profile

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by PlutonianEmpire on 3rd January 2014, 12:32 pm

If Proxima desides to flare during one of the events, will that cause any issues or make observations more difficult?

_________________
Circumbinary sunset! I love you
avatar
PlutonianEmpire
Planetesimal
Planetesimal

Number of posts : 136
Age : 32
Location : Minnesota
Registration date : 2012-01-29

View user profile http://www.plutonianempire.net/

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by Shellface on 3rd January 2014, 12:42 pm

Assuming that the centroid shifts of the two sources can be measured with an accuracy of 200 mas per epoch, Proxima’s mass can be measured with an accuracy of ∼5%.
Hey, that's great! 5% of 0.12 M is 0.006 M, or about 6 MJ. That's a very healthy accuracy for such a late-type star, And would be an excellent addition to the M-dwarf mass-luminosity relation.

If Proxima has planets in an "expectable" system (something like Kepler-42=KOI-961), then it's unfortunately rather likely that these events won't turn up anything. Still, there is the off-chance that an Earth-mass or Super-Earth-mass planet will be close enough to the background star to be detectable - which would be more than enough to make the search worthwhile!

PlutonianEmpire wrote:If Proxima desides to flare during one of the events, will that cause any issues or make observations more difficult?
I'm going to go with probably not. What will actually enable the detection of a companion is the presence of the background star, so Proxima's exact character isn't so important. The lensing events should also be considerably longer than any single flare event, so it likely wouldn't be that major anyway.

Shellface
Neptune-Mass
Neptune-Mass

Number of posts : 282
Location : g2 17.∞ 997 t
Registration date : 2013-02-14

View user profile

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by Lazarus on 3rd January 2014, 12:48 pm

Shellface wrote:
Assuming that the centroid shifts of the two sources can be measured with an accuracy of 200 mas per epoch, Proxima’s mass can be measured with an accuracy of ∼5%.
Hey, that's great! 5% of 0.12 M is 0.006 M, or about 6 MJ. That's a very healthy accuracy for such a late-type star, And would be an excellent addition to the M-dwarf mass-luminosity relation.
Yes, personally I think the opportunity for a direct mass measurement of a well-observed low-mass star is the most interesting thing about this. Any planets are a bonus, but I'm not getting my hopes up.
avatar
Lazarus
dG star
dG star

Number of posts : 2822
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by Baltazar on 19th October 2014, 4:17 pm

Have the earliest results arrived? Or is it too early?
avatar
Baltazar
Meteor
Meteor

Number of posts : 29
Registration date : 2011-01-08

View user profile

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by Lazarus on 19th October 2014, 4:52 pm

The paper gives the date of closest approach for source 1 as October 20th, uncertainty ± 10 days. Will probably be a while before we hear anything (actually come to think of it, do we know if the observation proposal was accepted?).
avatar
Lazarus
dG star
dG star

Number of posts : 2822
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by Lazarus on 10th August 2015, 2:48 pm

There's an update on this in the comments of the Centauri Dreams blog. Observations of the 2015 event were not sufficient to search for planets (though should be possible to get the mass measurement), hopefully the 2016 event will be followed with a higher frequency.
avatar
Lazarus
dG star
dG star

Number of posts : 2822
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Hubble search for planets around Proxima Centauri using microlensing

Post by Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum