Astronomy 61:
Current Problems in Astronomy and Astrophysics

Spring 2017
Prof. David Cohen



Archive of papers

 

For week 13 David R has chosen "The Snow Line in Viscous Disks around Low-mass Stars: Implications for Water Delivery to Terrestrial Planets in the Habitable Zone," Mulders et al., Ap.J., 807, 9 (2015).

Post at least one question on the new Moodle forum by Wednesday night. And then check back for replies.

Mulders Fig 6

 


For week 12 JJ has chosen "Water Vapor in the Protoplanetary Disk of DG Tau," Podio et al., Ap.J., 766, L5 (2013).

Post at least one question on the new Moodle forum by Wednesday night. And then check back for replies.

Podio Fig 1   Podio Fig 2

 


For week 11 Linda has chosen "Extrasolar Asteroid Mining as Forensic Evidence for Extraterrestrial Intelligence," Forgan & Elvis, International Journal of Astrobiology, 10, 307 (2011). This paper is a change of pace for us (and note the journal it's in). The connection to disks is via debris disks which are more evolved than the pre-main-sequence disks we've read a lot of papers about. After the gas is gone and the dust has coagulated into pebbles and boulders and objects like asteroids, and (maybe) planets have formed, a gas-less disk can be left behind. This debris disk full of rocks and asteroids will emit infrared light since the objects in it are heated up to a few 100 K by the central star. And they can sometimes be imaged (see the classic image of the debris disk around beta Pictoris, above and on the right (that image is not from the paper we're reading). You can read a little bit about debris disks on their wikipedia page.

Post at least one question on the new Moodle forum by Wednesday night. And then check back for replies.

Forgan and Elvis Fig 2   beta Pic

 


For week 10 Li has chosen "Disks and winds in Young Solar-Type Stars: the Magnetic Connection," Dougados, et al., IAU Symposium, 226, 491 (2005). Note that this is a conference paper (not refereed, and quite short). To supplement, Li asks that we also take a look at "Locking of the Rotation of Disk-Accreting Magnetized Stars," Long, et al., Ap.J., 634, 1214 (2005) and read the abstract and figures (not the whole paper).

Post at least one question on the new Moodle forum by Wednesday night. And then check back for replies.

Dougados Fig 1   Long Fig 3

 


For week 9 David C has chosen "A Keplerian-like Disk around the Forming O-type Star AFGL 4176," Johnston, et al., Astrophysical Journal Letters, 813, L19 (2015).

Post at least one question on the new Moodle forum by Wednesday night. And then check back for replies.

Johnston Fig 3

 


For week 8 Linda has chosen "A Newly Forming Cold Flow Protogalactic Disk, a Signature of Cold Accretion from the Cosmic Web," Martin, et al., Astrophysical Journal Letters, 824, L5 (2016).

Post at least one question on the new Moodle forum by Wednesday night. And then check back for replies.

Martin Fig 3

 


For week 7 we're going to continue "Classical Be stars: Rapidly Rotating B Stars with Viscous Keplerian Decretion Disks," Rivinius, Carciofi, & Martayan, Annual Reviews of Astronomy and Astrophysics, 21, 69 (2013).

For this week we'll read and discuss section 5, on Be star disks.

Post at least one question on the new Moodle forum by Wednesday night. And then check back for replies.


Rivinius Fig 14

 

For week 6 David R has chosen "Classical Be stars: Rapidly Rotating B Stars with Viscous Keplerian Decretion Disks," Rivinius, Carciofi, & Martayan, Annual Reviews of Astronomy and Astrophysics, 21, 69 (2013).

This is a review paper about Be stars – a class of B stars that show H-alpha in emission, due to the presence of circumstellar disks. These disks are decretion disks, which are fed by material coming off the surface of the central star. We will be reading and discussing only the material up through the end of sec. 2.

Post at least one question on the Moodle forum by Wednesday night. And then check back for replies.


Rivinius Fig 1   Rivinius Fig 6

 

For week 5 Stefan has chosen "A Photoevaporative Gap in the Closest Planet-Forming Disc," Ercolano, et al., Monthly Notices of the Royal Astronomical Society, 464, L95 (2017).

This is a theory paper, looking at photoevaporation as an explanation for gaps in dusty protoplanetary disks.

Post at least one question on the Moodle forum by Wednesday night. And then check back for replies.


Ercolano Fig 1   Ercolano Fig 2

 

For week 4 JJ has chosen "ALMA Observations of ρ-Oph 102: Grain Growth and Molecular Gas in the Disk around a Young Brown Dwarf," Ricci, et al., Astrophysical Journal Letters, 761, 20 (2012).

This is another paper using ALMA observations of a disk, but this time a disk around a brown dwarf.

Post at least one question on the Moodle forum by Wednesday night. And then check back for replies.

New: Read this article from Physics Today about the history of refereeing and peer review.


Ricci Fig 3   Ricci Fig 4

 

For week 3 Kira has chosen "A Major Asymmetric Dust Trap in a Transition Disk," van der Marel, et al., Science, 310, 1199 (2013). Note: for this paper, I recommend the html version, which has a link the supplementary material (see below).

This is another paper using ALMA observations of a protoplanetary disk. Note that it is in the journal Science, which is very prestigious and multi-disciplinary. Take a look at the table of contents of the issue this paper appeared in and see the wide range of subjects. Papers in Science tend to be short and terse/dense. Give yourself time to re-read the paper several times. But also note that like most of these short papers in Science (and in Nature, too) there is supplementary material. You should read the supplementary material [pdf], though you don't have to read it as carefully as the main article. Note in particular the figures in the supplementary material.

Post at least one question on the Moodle forum by Wednesday night. And then check back for replies.


van der Marel Fig 2   van der Marel Fig S2

 

For week 2 reread the paper with fresh eyes. Post another question or two if you are moved. I will start answering questions again on Wednesday evening. Also, I'd like two students to volunteer to spend a few minutes presenting Figure 2 and Figure 3. Please get in touch with me to volunteer to present one of these figures in class on Friday.

For week 1 (and to be continued for week 2), David has chosen "The 2014 ALMA Long Baseline Campaign: First Results from High Angular Resolution Observations toward the HL Tau Region," ALMA Partnership, Brogan, et al., ApJ, 808, L3 (2015).

This is the discovery paper of the dramatic circumstellar disk around a young star in Taurus, which shows intriguing/suggestive gaps that could indicate the presence of forming planets. David will post a summary the article on Moodle by Thursday night, and the rest of us should post questions by 9 PM that night. Note that this discovery was the subject of an Astronomy Picture of the Day post.


ALMA HL Tau Fig 4

 

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Last modified: April 23, 2017