Recent site activity

LPV Humps

A number of AAVSO observers are working on this project, and can often be found in the AAVSO chat room. If you have an interest let me know.

  • SFRA Frank Schorr - fschorr at comcast dot net
  • Special thanks to MDW Walter MacDonald
  • Special thanks to Neil Butterworth

Introduction:

We started this project for the learning experience and to delve deeper into the aspects of the  "humps" on  light curves of various LPVs we've noticed while observing .  At this point this is not a "scientific" project but a project to create a list or "catalog" and gather more information on LPVs that show this particular type of behavior to see if there is a reason to start a scientific "project" to discover more about this type of behavior.

These "humps" or "bumps" seem to mostly appear on the rising portion of LPV's light curve as seen in the light curve of the last 900 days of RU HER above.  A "hump" is a spot on the light curve where the slope of the curve is altered to make it look like the brightening (or dimming) of the LPV "stalls" for a period of time.   (sometimes this is called "stalling" or a "shoulder"l) 

Sometimes the brightness (or dimness) reverses direction giving the impression of an early maxima or even a double maxima for that cycle.  This may or may not be related to the "double" or "dual" maxima behavior of some "LPV" stars.

Note (3/25/2010): 

It has been brought to our attention that there has been a Variable Star South research project underway for the last year or so that is looking at LPV's that appear to have "double maximas" and possible related "humps/bumps".  The project's name is "Dual-Maxima Miras" and it's project page is at:

http://www.variablestarssouth.org/index.php?option=com_content&view=article&id=32&Itemid=10

This group is planning on having a paper published early 2011.

Note (12/2/2010):

A paper published in Astrophysics, Vol. 50, No. 1, 2007, titled  "VARIABILITY OF LONG-PERIOD PULSATING STARS. III. CHANGES IN THE PARAMETERS OF HUMPS AT THE ASCENDING BRANCH" by V. I. Marsakova and I. L. Andronov, may have answered a lot of the questions I have concerning the "humps".  The paper can be found at.
http://www.springerlink.com/content/q82910824434n110/.  Thanks to James Bedient for this information.

There are two more papers in this series that talks about the methods used to produce the data in the above paper:

     Variability of long-period pulsating stars. I. Methods for analyzing observations - http://www.springerlink.com/content/n611125846588r70/

     Variability of long-period pulsating stars. II. Additional parameters for classifying stars - http://www.springerlink.com/content/y03752753h358375/

James also provides the following information:

"We have a parallel investigation going on over at Citizen Sky, the Mira Fourier Coefficient Team (http://www.citizensky.org/teams/mira-fourier-coefficient-team). Our goal there is to take a subset of about 400 LPVs and determine the Fourier coefficients of their visual light curves, and examine how they change over time. The Fourier coefficients mathematically describe the shape of the light curve, including the presence or absence of a hump. Please come on over and check it out, and join us!"t

Discovery/Identification:
  • Sampled the light curves for about 450 LPVs using data for the last 10 years from the AAVSO International database and the ASAS2 and 3 database
  • 57 LPVs that appears to have "hump" events - please see Table 1 below
  • 30 or so possible candidates - Please see Table 2

Table 1:

List of 57 LPVs that show distinct "humps" and/or double maximas since 2000.  Please click on the star name to see a light curve for that star and possible other data.  Stars high-lighted in yellow are approaching a potential "hump" event.  Stars high-lighted in red in currently having a "hump" event.


  RA (J2000.0)  DEC (J2000.0)  Star
 Event type  Cycle Period
 Spectrum  N d (4)
 Type Source
 Next Event (JD)
 Next Event Calendar
 Comments
 00 23 13.27  +55 47 33.2  T-CAS  Dual Maxima?      2.61    T. Lange    3/6/2011  T CAS may be starting a hump/ Dual Maxima event.  This is a prime time to get observations. 1/29/2012
 00 54 53.85  +58 33 49.2  W-CAS  Hump on RLC  405.50  C7,1e  .47    SFRA      
 01 19 41.97  +72 36 40.7   S-CAS  Hump on RLC  612.4  S3,4e-S5,8e  .59    SFRA      
 02 29 15.31  -26 05 55.7   R-FOR  Hump on RLC  388.7  C4,3e(Ne)  1.21    SFRA      
 04 33 32.83  -63 01 45.0  R-RET  Hump on RLC  278.6  M4e-M7.5e  .57    SFRA  
   
 04 40 08.87  +66 08 48.6  T-CAM  Hump and DM?  373.2  S4,7e-S8.5,8e  .61          
 04 40 30.09  -38 14 06.9  R-CAE  Hump on RLC  391  M6e  1.11    SFRA      
 05 17 17.69
 +53 35 10.1
 R AUR
 Hump on RLC  458  M6.5e-M9.5e  1.71          
 05 29 00.90  -04 41 32.8   S-ORI  Hump on RLC  @420  M6.5e-M9.5e  3.81m  D  SFRA  2455648  3/27/2011  Study Star
 05 41 56.59   +38 55 55.8  SZ-AUR  Hump on RLC  457.5  M6.5e-M9.5e  1.08  D        
 05 52 36.80  +15 58 14.4  RU-TAU  Hump on RLC  544.6  M3.5e-M6.5  3.52  D?  SFRA      Study Star -
 05 55 49.17  +20 10 30.7  U-ORI  Hump on RLC  368.3  M6e-M9e  .33    SFRA      
 06 02 32.28  +74 30 27.2  V-CAM      M7e  .28    SFRA      *
 06 17 53.0  -00 20 33.5  S-SEX  Moving Hump?  264.9  M2e-M5e  2.85    SFRA      *
 06 26 42.88   +47 14 23.6  GQ-AUR
 Hump on RLC  304.8   M3  .87  S   MDW      
 07 01 18.01  +55 19 49.8  R-LYN  Hump on RLC  378.8  S2.5,5e-S6,8e  3.53    SFRA      *
 07 05 36.20  -73 00 52.0  R-VOL  Hump on RLC  453.6   C(N)e  .54    SFRA      
 07 29 45.58  -73 22 44.0  S-VOL  Hump on RLC  394.8  M4e  1.09    SFRA      
 07 41 20
 +08 22 49
 u-cmi
 Hump on RLC
 413.9 M4e   MDW   New addition to list - Thank you Walter
 09 44 58.97  -24 01 15.7  RR-HYA  Hump on RLC  343.5  M3.0e-M8e  .65    SFRA      *
 09 52 54.28   -54 10 47.9  Z-VEL  Hump on RLC  411.4  M9e  .17    SFRA      
 10 24 25
 -60 11 29
 CK-CAR
 Dual Maxima
 266 M3.5lab       SRC - New addition to list - Thank you Walter
 10 51 19
 -28 3 41
 RS-HYA
 Hump on RLC
 338.6 M6e 2.86     New addition to list - Thank you Walter
 10 52 05.5
 -62 28 59.6
 BX-CAR
 Dual Maxima
 427 M7e      SRA - New addition to list - Thank you Walter
 12 16 16.79  -56 17 09.6  BH-CRU  Hump on RLC  530  SC4.5/8-e- SC7/8-e  6.09    BIW      "Dual-Maxima Mira project" star
 13 29 42.78  -23 16 52.8  R-HYA  Hump on RLC   388.9  M6e-M9eS (Tc)  8.01    SFRA     "Dual-Maxima Mira project" star
 13 34 41.05  +73 25 52.9  T-UMI  Hump on RLC  301  M4e-M6e  23.90    G. Foster      *
14 16 34.32  -59 54 49.3  R-CEN  Moving Hump?  546.2  M4e-M8iie  8.63    SFRA      "Dual-Maxima Mira project" star
15 21 39.53
 +14 18 53.1  S-SER  Hump on RLC  371.8  M5e-M6e  1.59    SFRA      *
 00 15 22.27  -32 02 43.0  S-SCL  Hump on RLC  362.5  M3e-M93(Tc)  2.27    SFRA      
 15 35 57.35  -49 30 28.7  R-NOR  Double Maxima  507.5  M3e-M6ii  2.89    M. Templeton      "Dual-Maxima Mira project" star
 16 10 14.52  +25 04 14.4  RU-HER  Hump on RLC   484.3  M6e-M9  .89  D  SFRA      * Study Star
 16 51 53.92  +14 56 30.7  S-HER  Hump on RLC  307.3  M4,Se-M7.5,Se  .75    R. Huziak    
 16 59 49.73  +52 19 04.4  WZ-DRA  Hump on RLC  401.7  M6e          
 17 42 25.21  -43 45 01.3  RU-SCO  Hump on RLC  370.8  M4/6e-M7ii-iiie  3.70    SFRA  
   
 17 54 10.57  -34 20 27.3  BN-SCO  Hump on RLC  616  ?            "Dual-Maxima Mira project" star
 18 28 48.74  +06 17 53.0  T-SER  Hump on RLC  338.1  M7e  .19    SFRA      
 18 44 52.11  +34 40 33.4  RY-LYR  Hump on RLC    325.8  .15    SFRA      *
 19 13 54.60  -18 51 42.1  RX-SGR  Hump on RLC  335.2  M5e  .87    SFRA      
 19 19 52.46  -31 42 53.9  SW-SGR  Hump on RLC   289.9  M5e-M8  1.19    SFRA      
 19 50 33.92  +32 54 50.6  CHI-CYG  Hump on RLC  408  S6,2e-S10,4e(MSe)  .63    R. Huziak      Khi CYG started a "hump/stall" event a few days ago (1/29/2012)
 20 05 29.85  +57 59 09.1  S-CYG    322.9  S2.5.1e (M3.5-M7e)  1.39    R. Huziak      * No event for a number of cycles
 20 14 45.12  -46 58 55.0  R-TEL  Hump on RLC  467  M5iie-M7e      SFRA      
 20 15 33.52  +31 04 20.1  SX CYG  Hump on RLC  411  M7e  .08    SFRA      
  20 32 33.48  +54 57 00.5  ST-CYG  Hump on RLC  337.3  M5.5e-M8.0e  .23     R. Huziak      
  21 09 31.78  +68 29 27.2  T-CEP  Hump on RLC  388.1  M5.5e-M8.8e 1.47 m          
 21 35 12.83  +78 37 28.2  S-CEP  Moving Hump?  486.8  C7,4e(N8e)  1.01    Marsakova      *
 22 07 29.82 +37 44 07.1 W-LAC Hump on RLC 328.5 M7e-M8e3.28 S SFRA   
 22 08 54.31  +12 32 24.5  T-PEG  Hump on RLC  379.4  M6e-M8e  1.73    SFRA      
 22 12 16.18  +14 33 12.2  RS-PEG
 Hump on RLC  415.4  M6e-M9e  3.40    SFRA      
 22 23 12.87  -22 03 23.8  RT-AQR  Moving Hump?
 252.2  M5e-M6e  .39    SFRA      
 22 25 40.93  -37 34 09.2  T-GRU  DM?  136.5  M1iae-M2ibe  .53    SFRA      
 22 57 06.49   -20 20 35.5  S-AQR  Hump on RLC  279.3  M4e-M6e  1.47    SFRA      
 23 06 39.17  +10 32 36.1  R-PEG  Hump on RLC  378.1  M6e-M9e  .91    SFRA    
 23 19 50.50  +26 16 43.6  W-PEG  Hump on RLC  345.5  M6e-M8e  .54    SFRA  2455760  7/17/2011  
 23 20 32.62  +08 55 08.2  S-PEG  Hump on RLC  319.2  M5e-M8.5e  .70    SFRA      
 23 56 27.56  -49 47 12.6  R-PHE  Hump on RLC  269.3  M2(ii)e- M4(iii)e  .99    SFRA      
                       
                       

Table 2

Below is a table of LPV hump stars candidates.

Those with event predictions are listed first in order of date. The rest are listed in order of RA.
Some of these stars may not be hump stars, particularly those flagged in red, and probably those flagged in yellow

 COORDS    STAR  Type  N d (4)
 Next Event
 Curve  Source  Status
 0051+34    RR AND   Asc  .34  2010/08/11  RR-AND  MDW  
 0540+37     RU AUR  Asc  1.21  2011/04/26  RU-AUR  MDW  *
 0732-20    Z PUP   1.22
   Z-PUP    * Small hump at JD 2454818
 0942+11    R LEO    2.20      SFRA  small hump on last cycle
 1319-60    TT CEN  Asc    2011/04/26  TT-CEN    "Dual-Maxima Mira project" star
 1513+36    RT BOO    1.16        JAAVSO V33 page 52
 1625+18    U HER  Asc  .04  2010/08/02  U-HER  SFRA  Showing promise
 1845+43    RW LYR  Desc  .81  2011/05/14  RW-LYR  SFRA  * - starting descend 5/15/2011
 1910+67    U DRA  Asc  2.46  2010/11/19  U-DRA    
 2013+38    RS CYG
 Dbl Max?
   2010/01/10  RS-CYG  SFRA  SRA
  2049+31    AM CYG  Asc    2011/02/04  AM-CYG    
 2105+29    TW CYG  Asc  2.37  2011/02/01  TW-CYG  SFRA  *
 2122+21    SW PEG
 Asc.    2010/06/01  SW-PEG    
 2111+13    AN PEG
 Asc.  3.02  2010/07/30  AN-PEG    
     U UMI
 Asc  2.21        
  19 13 20.82  +32 03 17.7  EL LYR
 Asc  2.81        Last cycle
     WZ GEM
 Asc  2.83        look closer at 6 cycles ago
                 
     
       
   
     R AQR
 Dbl Max           "Dual-Maxima Mira project" star
 0932-62    R CAR
   17.02        
 1003-46    V415 VEL
           SRA - "Dual-Maxima Mira project" star
 1053-61    CL CAR
 Unstable      CL-CAR    SRC - Unstable light curve -  "Dual-Maxima Mira project" star
     UZ CIR
 Dbl Max           "Dual-Maxima Mira project" star
     FK PUP
 Dbl Max           SR - "Dual-Maxima Mira project" star
 1305-26    KN HYA
 Asc & Desc
     kn-hya   SR -  Ascending & descending
 1606-21    Z SCO
 Desc?  .00    Z-SCO    


Classification/Description:

Some ideas:
 
- Accurately measure the time from the Maxima at the beginning of the cycle to the Maxima at the end of the cycle for each LPV that shows hump event.  Accurately measure each period for that LPVs for all cycles (get the period of the cycle).  If a particular cycle does not have a "hump" in it compare it's period to the period of a cycle with a "hump" event to see if this affects the cycle period.

- Measure the time from the Maxima at the beginning of the cycle to the beginning of "hump" event to understand how far into each cycle the "hump" event starts and the relationship of the start of the event from the beginning Maxima to the length of the overall cycle.  Compare this value between cycles for the same LPV

- Measure the time from the beginning of the hump to the end of the hump.  Compare how the length of the "hump" event changes between cycles.

- Calculate the length of the "hump" event compared to the length of the period of the cycle the hump occurs in to see if there is a relationship.

- Calculate the length of the "hump" events between cycles to see if there is a period to the "length".

- Calculate the length of time from the beginning or one "hump" event to the beginning of the next "hump" event to see if there any hidden periods in the "hump" events.

- Any other suggestions?

Footnotes

Note 1 - "Fast Variations of the Mean Brightness and Other Light Curve Parameters of the Carbon Mira-Type Star S CEP", JAAVSO Volume 27, Number 2, 1999, Pages 141-145, Vladislova I. Marsakova. He describes in detail the "hump" on the ascending curve that this star showed for about a half of it's studied cycles. He also reports two cycles in a rows between JD 2428250 and 242950 where the light curve becomes unstable with an almost Double Maxima look on the second cycle. Currently, the last cycle of S Cep showed this same type of unstable behavior. (about JD 2454423 to 2454894) Perhaps the next cycle of will continue this behavior. At the time of writing (Feb 7 2010) it appears the S CEP is around minima so this could be a good star to observe over the next couple of months.

(5/24/2010) - It looks like S-CEP might be having a longer minima then it normally does.

Note 2 - JAAVSO Volume 25, Number 2, 1997, page 58

Note 3 - N.D. Melikian, Astrophysics, Voll. 42, No. 4, 1999, pages 408-418 - He did a study of 223 Miras with light curve information from the HIPPARCOS space telescop. No list of the stars studied is supplied.

References and articles

Good article on Humps and Bumps: http://www.aavso.org/vstar/templeton.pdf


Mattei, Mayall and Waagen, "Maxima and Minima of Long Period Stars, 1949-1975", AAVSO


M.R Templeton, J.A. Mattei and L.A. Willson, "Secular Evolution in MIRA Variable Pulsations", The Astronomical Journal, 130:776-778, 2005 August



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Mike Simonsen,
Feb 23, 2010, 8:55 PM
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